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Document and Entity Information Document - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Feb. 16, 2018	Jun. 30, 2017
Document Information [Line Items]
Entity Registrant Name	APPFOLIO INC
Entity Central Index Key	0001433195
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Public Float			$ 398.7
Class A common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		14,966,515
Class B common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		19,102,408

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 16,109	$ 10,699
Investment securities—current	29,800	15,473
Accounts receivable, net	3,387	2,511
Prepaid expenses and other current assets	4,546	3,537
Total current assets	53,842	32,220
Investment securities—noncurrent	22,401	26,688
Property and equipment, net	6,696	7,077
Capitalized software, net	17,609	15,539
Goodwill	6,737	6,737
Intangible assets, net	1,725	3,105
Other assets	1,238	1,217
Total assets	110,248	92,583
Current liabilities
Accounts payable	610	937
Accrued employee expenses	10,710	7,550
Accrued expenses	4,289	4,044
Deferred revenue	7,080	7,638
Other current liabilities	1,223	1,192
Total current liabilities	23,912	21,361
Other liabilities	1,257	1,540
Total liabilities	25,169	22,901
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock, $0.0001 par value, 25,000 authorized and no shares issued and outstanding as of December 31, 2017 and 2016	0	0
Additional paid-in capital	152,531	146,692
Accumulated other comprehensive loss	(209)	(51)
Accumulated deficit	(67,247)	(76,963)
Total stockholders’ equity	85,079	69,682
Total liabilities and stockholders’ equity	110,248	92,583
Class A common stock, $0.0001 par value, 250,000 shares authorized as of December 31, 2017 and 2016; 14,879 and 11,691 shares issued and outstanding as of December 31, 2017 and 2016, respectively
Stockholders’ equity:
Common stock	1	1
Class B common stock, $0.0001 par value, 50,000 shares authorized as of December 31, 2017 and 2016; 19,102 and 22,028 shares issued and outstanding as of December 31, 2017 and 2016, respectively
Stockholders’ equity:
Common stock	$ 3	$ 3

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Preferred stock, par value (usd per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Class A common stock
Common stock, par value (usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	14,879,000	11,691,000
Common stock, shares outstanding	14,879,000	11,691,000
Class B common stock
Common stock, par value (usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	19,102,000	22,028,000
Common stock, shares outstanding	19,102,000	22,028,000

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenue	$ 143,803	$ 105,586	$ 74,977
Costs and operating expenses:
Cost of revenue (exclusive of depreciation and amortization)	55,283	44,630	33,903
Sales and marketing	28,709	28,827	26,076
Research and product development	16,578	12,638	9,554
General and administrative	21,199	17,979	14,343
Depreciation and amortization	12,699	9,935	6,104
Total costs and operating expenses	134,468	114,009	89,980
Income (loss) from operations	9,335	(8,423)	(15,003)
Other income (expense), net	(96)	(37)	5
Interest income (expense), net	535	246	(595)
Income (loss) before provision for income taxes	9,774	(8,214)	(15,593)
Provision for income taxes	58	67	75
Net income (loss)	$ 9,716	$ (8,281)	$ (15,668)
Net income (loss) per common share:
Basic (in usd per share)	$ 0.29	$ (0.25)	$ (0.73)
Diluted (in usd per share)	$ 0.28	$ (0.25)	$ (0.73)
Weighted average common shares outstanding:
Weighted average common shares outstanding; basic	33,849	33,561	21,336
Weighted average common shares outstanding; diluted	35,151	33,561	21,336

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 9,716	$ (8,281)	$ (15,668)
Other comprehensive income (loss):
Changes in unrealized gains (losses) on investment securities	(158)	102	(153)
Comprehensive income (loss)	$ 9,558	$ (8,179)	$ (15,821)

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Convertible preferred stock	Common stock Class A common stock	Common stock Class B common stock	Additional paid-in capital	Accumulated other comprehensive loss	Accumulated deficit
Beginning balance (shares) at Dec. 31, 2014		68,027,000
Beginning balance at Dec. 31, 2014		$ 63,166
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of convertible preferred stock in connection with initial public offering (shares)		(68,027,000)
Conversion of convertible preferred stock in connection with initial public offering		$ (63,166)
Ending balance (shares) at Dec. 31, 2015		0
Ending balance at Dec. 31, 2015		$ 0
Beginning balance (shares) at Dec. 31, 2014			0	9,042,000
Beginning balance at Dec. 31, 2014	$ (51,467)		$ 0	$ 1	$ 1,546	$ 0	$ (53,014)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (shares)			2,000	315,000
Exercise of stock options	357				357
Stock-based compensation	1,103				1,103
Conversion of convertible preferred stock in connection with initial public offering (shares)				17,007,000
Conversion of convertible preferred stock in connection with initial public offering	63,166			$ 2	63,164
Issuance of common stock in connection with initial public offering, net of offering costs (shares)			7,130,000
Issuance of common stock in connection with initial public offering, net of offering costs	75,359		$ 1		75,358
Conversion of Class B stock to Class A stock (shares)			1,848,000	(1,848,000)
Conversion of Class B stock to Class A stock	0
Issuance of restricted stock awards (shares)			25,000	25,000
Issuance of restricted stock awards	0
Other comprehensive income (loss)	(153)					(153)
Net income (loss)	(15,668)						(15,668)
Ending balance (shares) at Dec. 31, 2015			9,005,000	24,541,000
Ending balance at Dec. 31, 2015	72,697		$ 1	$ 3	141,528	(153)	(68,682)
Ending balance (shares) at Dec. 31, 2016		0
Ending balance at Dec. 31, 2016		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (shares)			140,000	1,000
Exercise of stock options	352				352
Stock-based compensation	4,495				4,495
Vesting of restricted stock units, net of shares withheld for taxes (shares)			10,000
Vesting of restricted stock units, net of shares withheld for taxes	127				127
Vesting of early exercised shares	190				190
Conversion of Class B stock to Class A stock (shares)			2,514,000	(2,514,000)
Conversion of Class B stock to Class A stock	0
Issuance of restricted stock awards (shares)			22,000
Issuance of restricted stock awards	0
Other comprehensive income (loss)	102					102
Net income (loss)	(8,281)						(8,281)
Ending balance (shares) at Dec. 31, 2016			11,691,000	22,028,000
Ending balance at Dec. 31, 2016	$ 69,682		$ 1	$ 3	146,692	(51)	(76,963)
Ending balance (shares) at Dec. 31, 2017		0
Ending balance at Dec. 31, 2017		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (shares)	165,000		165,000
Exercise of stock options	$ 663				663
Stock-based compensation	6,618				6,618
Vesting of restricted stock units, net of shares withheld for taxes (shares)			88,000
Vesting of restricted stock units, net of shares withheld for taxes	(1,559)				(1,559)
Vesting of early exercised shares	117				117
Conversion of Class B stock to Class A stock (shares)			2,926,000	(2,926,000)
Conversion of Class B stock to Class A stock	0
Issuance of restricted stock awards (shares)			9,000
Issuance of restricted stock awards	0
Other comprehensive income (loss)	(158)					(158)
Net income (loss)	9,716						9,716
Ending balance (shares) at Dec. 31, 2017			14,879,000	19,102,000
Ending balance at Dec. 31, 2017	$ 85,079		$ 1	$ 3	$ 152,531	$ (209)	$ (67,247)

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash from operating activities
Net income (loss)	$ 9,716	$ (8,281)	$ (15,668)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	12,699	9,935	6,104
Purchased investment premium, net of amortization	(39)	245	(865)
Amortization of deferred financing costs	63	63	456
Loss on disposal of property, equipment and intangibles	97	41	67
Stock-based compensation	6,096	4,301	1,007
Lease abandonment	0	161	0
Changes in operating assets and liabilities:
Accounts receivable	(876)	(463)	(746)
Prepaid expenses and other current assets	(1,009)	(377)	(1,893)
Other assets	(84)	(103)	(56)
Accounts payable	(100)	(904)	(439)
Accrued employee expenses	3,243	2,223	1,887
Accrued expenses	271	1,148	1,135
Deferred revenue	(558)	2,685	1,173
Other liabilities	(148)	826	994
Net cash provided by (used in) operating activities	29,371	11,500	(6,844)
Cash from investing activities
Purchases of property and equipment	(2,213)	(4,242)	(3,694)
Additions to capitalized software	(10,455)	(11,166)	(7,677)
Purchases of investment securities	(26,648)	(31,551)	(74,176)
Sales of investment securities	15	12,559	4,100
Maturities of investment securities	16,474	21,337	26,136
Cash paid in business acquisition, net of cash acquired	0	0	(4,039)
Purchases of intangible assets	(1)	(2)	(17)
Net cash used in investing activities	(22,828)	(13,065)	(59,367)
Cash from financing activities
Proceeds from stock option exercises	663	352	357
Proceeds from issuance of restricted stock	0	0	141
Proceeds from issuance of options	0	0	208
Tax withholding for net share settlement	(1,796)	(111)	0
Principal payments under capital lease obligations	0	(29)	(27)
Proceeds from initial public offering, net of underwriting discounts and commissions	0	0	79,570
Payments of initial public offering costs	0	0	(4,213)
Payment of contingent consideration	0	0	(2,429)
Proceeds from issuance of debt	118	117	10,253
Principal payments on debt	(118)	(128)	(10,241)
Payment of debt issuance costs	0	0	(757)
Net cash (used in) provided by financing activities	(1,133)	201	72,862
Net increase (decrease) in cash and cash equivalents	5,410	(1,364)	6,651
Cash and cash equivalents
Beginning of period	10,699	12,063	5,412
End of period	16,109	10,699	12,063
Supplemental disclosure of cash flow information
Cash paid for interest	182	191	797
Cash paid for taxes	30	27	91
Noncash investing and financing activities
Purchases of property and equipment included in accounts payable and accrued expenses	21	261	1,220
Additions of capitalized software included in accrued employee expenses	374	458	290
Stock-based compensation capitalized for software development	759	431	166
Conversion of convertible preferred stock into common stock in connection with initial public offering	$ 0	$ 0	$ 63,166

Nature of Business	12 Months Ended
Nature of Business	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Nature of Business AppFolio, Inc. (“we”, the "Company" or “AppFolio”) provides industry-specific, cloud-based software solutions to the real estate market, which comprises a significant majority of our revenue, as well as to the legal market, and we intend to enter new vertical markets over time. We serve small and medium-sized businesses (“SMBs”) in the property management industry and solo practitioners and small law firms in the legal industry. We refer to solo practitioners and small law firms as SMBs in connection with our legal vertical in these financial statements. Our solutions are designed to be a system of record to automate essential business processes, a system of engagement to enhance business interactions between our customers and their clients and vendors, and, increasingly, a system of intelligence to anticipate, influence, and optimize customer experiences using data to take action in real time.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Presentation and Significant Accounting Policies

The accompanying Consolidated Financial Statements were prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”).

Principles of Consolidation

The accompanying Consolidated Financial Statements include the operations of AppFolio, Inc. and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.

Our investment in SecureDocs, Inc. (“SecureDocs”) is accounted for under the equity method of accounting as we have the ability to exert significant influence, but do not control and are not the primary beneficiary of the entity. Our investment in SecureDocs and our share of its losses are not material individually or in the aggregate to our financial position, results of operations or cash flows for any period presented.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the dates of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ materially from those estimates. On an ongoing basis, management evaluates its estimates based on historical data and experience, as well as various other factors that management believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources.

Segment Information

Our chief operating decision maker reviews financial information presented on an aggregated and consolidated basis, together with revenue information for our core solutions, Value+ and other service offerings, principally to make decisions about how to allocate resources and to measure our performance. Accordingly, management has determined that we have one reportable and operating segment.

Concentrations of Credit Risk

Financial instruments that potentially subject us to credit risk consist principally of cash, accounts receivable, investment securities and notes receivable. At times, we maintain cash balances at financial institutions in excess of amounts insured by United States government agencies or payable by the United States government directly. We place our cash with high credit, quality financial institutions. We invest in investment securities with a minimum rating of A by Standard & Poor's and A-1 by Moody's and regularly monitor our investment security portfolio for changes in credit ratings.

Concentrations of credit risk with respect to accounts receivable and revenue are limited due to a large, diverse customer base. No individual customer represented 10% or more of accounts receivable as of December 31, 2017 and 2016 or revenue for the years ended December 31, 2017, 2016 and 2015.

Fair Value Measurements

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date.

Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Accounting Standard Codification (“ASC”) 820, Fair Value Measurements and Disclosures (“ASC 820”), describes a fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value, which are the following:

Level 1 - Quoted prices in active markets for identical assets or liabilities or funds.

Level 2 - Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.


	Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Cash and Cash Equivalents and Restricted Cash

We consider all highly liquid investments, readily convertible to cash, and which have a remaining maturity date of three months or less at the date of purchase, to be cash equivalents. Cash and cash equivalents are recorded at fair value and consist primarily of bank deposits and money market funds.

Restricted cash of $0.4 million as of December 31, 2017 and 2016, is comprised of certificates of deposits relating to collateral requirements for customer automated clearing house and credit card chargebacks and minimum collateral requirements for our insurance services, which are recorded in other long term assets.

Investment Securities

Our investment securities currently consist of corporate bonds, United States government agency securities ("Agency Securities") and certificates of deposit. We classify investment securities as available-for-sale at the time of purchase and reevaluate such classification as of each balance sheet date. All investments are recorded at estimated fair value. Unrealized gains and losses for available-for-sale securities are included in accumulated other comprehensive income (loss), a component of stockholders’ equity. We classify our investments as current when the period of time between the reporting date and the contractual maturity is twelve months or less and as noncurrent when the period of time between the reporting date and the contractual maturity is more than twelve months.

We evaluate our investments to assess whether those with unrealized loss positions are other than temporarily impaired. We consider impairments to be other than temporary if they are related to deterioration in credit risk or if it is likely we will sell the securities before the recovery of their cost basis. Declines in value judged to be other than temporary are determined based on the specific identification method and are reported in other income (expense), net in the Consolidated Statements of Operations.

Accounts Receivable

Accounts receivable are recorded at the invoiced amount, net of an allowance for doubtful accounts. The allowance for doubtful accounts is based on historical loss experience, the number of days that receivables are past due, and an evaluation of the potential risk of loss associated with delinquent accounts. Accounts receivable considered uncollectable are charged against the allowance for doubtful accounts when identified. We do not have any off-balance sheet credit exposure related to our customers. As of December 31, 2017, 2016 and 2015, our allowance for doubtful accounts was not material.

Property and Equipment

Property and equipment is stated at cost, less accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of assets. The estimated useful lives of our property and equipment are as follows:



Asset Type		Depreciation Period
Data center and computer equipment		3 years
Furniture and fixtures		7 years
Office equipment		2 to 5 years
Leasehold improvements		Shorter of remaining life of lease or asset life

Repair and maintenance costs are expensed as incurred. Renewals and improvements are capitalized. Assets disposed of or retired are removed from the cost and accumulated depreciation accounts and any resulting gain or loss is reflected in our results of operations.

Leases

Leases are evaluated and classified as either operating or capital leases. All of our office space leases are operating leases.

Rent expense under operating leases is recognized on a straight-line basis over the lease term. The difference between recognized rent expense and the rent payment amount is recorded as an increase or decrease in deferred rent liability. If the lease has tenant allowances from the lessor for certain improvements made to the leased property, these allowances are capitalized as leasehold improvements. Tenant allowances and rent holidays in lease agreements are recognized as a deferred rent credit, which is amortized on a straight-line basis over the lease term as a reduction of rent expense.

Internal-Use Software

We account for the costs of computer software obtained or developed for internal use in accordance with ASC 350, Intangibles-Goodwill and Other (“ASC 350”). These include costs incurred in connection with the development of our internal-use software solutions when (i) the preliminary project stage is completed, (ii) management has authorized further funding for the completion of the project and (iii) it is probable that the project will be completed and performed as intended. These capitalized costs include personnel and related expenses for employees who are directly associated with and who devote time to internal-use software projects and, when material, interest costs incurred during the development. Capitalization of these costs ceases once the project is substantially complete and the software is ready for its intended purpose. Costs incurred for significant upgrades and enhancements to our software solutions are also capitalized. Costs incurred for post-configuration training, maintenance and minor modifications or enhancements are expensed as incurred. Capitalized software development costs are amortized using the straight-line method over an estimated useful life of three years. We do not transfer ownership of our software, or lease our software, to third parties.

Intangible Assets

Intangible assets primarily consist of customer and partner relationships, acquired technology, trademarks, domain names and patents, which are recorded at cost, less accumulated amortization. We determine the appropriate useful life of our intangible assets by performing an analysis of expected cash flows of the acquired assets. Intangible assets are amortized over their estimated useful lives using the straight-line method, which approximates the pattern in which the economic benefits are consumed.

Impairment of Long-Lived Assets

We assess the recoverability of our long-lived assets when events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. An impairment charge would be recognized when the carrying amount of a long-lived asset or asset group is not recoverable and exceeds its fair value. The carrying amount of a long-lived asset or asset group is not recoverable if it exceeds the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset or asset group. There were no impairment charges related to the identified long-lived assets for the years ended December 31, 2017, 2016 and 2015.

Business Combinations

The results of a business acquired in a business combination are included in our consolidated financial statements from the date of acquisition. We allocate the purchase price, including the fair value of contingent consideration, to the identifiable assets and liabilities of the acquired business at their acquisition date fair values. The excess of the purchase price over the amount allocated to the identifiable assets and liabilities, if any, is recorded as goodwill.

Determining the fair value of assets acquired and liabilities assumed requires management to make significant judgments and estimates, including the selection of valuation methodologies, estimates of future revenue and cash flows, discount rates and selection of comparable companies.

Acquisition-related transaction costs are not included as a component of consideration transferred, but are accounted for as an operating expense in the period in which the costs are incurred.

Goodwill

Goodwill represents the excess of the purchase price over the fair value of net assets acquired in a business combination. We test goodwill for impairment in accordance with the provisions of ASC 350. Goodwill is tested for impairment at least annually at the reporting unit level or whenever events or changes in circumstances indicate that goodwill might be impaired. Events or changes in circumstances which could trigger an impairment review include a significant adverse change in legal factors or in the business climate, unanticipated competition, loss of key personnel, significant changes in the use of the acquired assets or our strategy, significant negative industry or economic trends, or significant underperformance relative to expected historical or projected future results of operations.

ASC 350 provides that an entity has the option to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, after assessing the totality of events or circumstances, an entity determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then additional impairment testing is not required. However, if an entity concludes otherwise, then it is required to perform the first of a two-step impairment test.

The first step involves comparing the estimated fair value of a reporting unit with its book value, including goodwill. If the estimated fair value exceeds book value, goodwill is considered not to be impaired and no additional steps are necessary. If, however, the fair value of the reporting unit is less than book value, then the carrying amount of the goodwill is compared with its implied fair value. The estimate of implied fair value of goodwill may require valuations of certain internally generated and unrecognized intangible assets. If the carrying amount of goodwill exceeds the implied fair value of that goodwill, an impairment loss is recognized in an amount equal to the excess.

We have one reporting unit and we test for goodwill impairment annually during the fourth quarter of the calendar year. At December 31, 2017 and 2016, we determined our goodwill of $6.7 million was not impaired as the fair value of our reporting unit significantly exceeded its carrying value based on the results of our annual impairment tests.

Revenue Recognition

We generate revenue primarily from our customers for subscriptions to access our core solutions and Value+ services for our cloud-based property management and legal software solutions. Subscription fees for our core solutions are charged on a per-unit per-month basis for our property management software solution and on a per-user per-month basis for our legal software solution. We recognize subscription revenue on a straight-line basis over the terms of the subscription agreements, which range from one month to one year. We generally invoice our customers for subscription services in monthly, quarterly or annual installments, typically in advance of the subscription period. Any revenues which are billed in advance are recorded as deferred revenue until the revenue is earned. Revenue from subscription services is impacted by the change in the number and type of our customers, the size and needs of our customers' businesses and our customer renewal rates.

We charge our customers on a subscription basis for certain of our Value+ services. Our subscription fees are designed to scale to the size of our customers’ businesses. Subscription Value+ services include website hosting services and contact center services. We also charge our customers usage-based fees for using certain Value+ services. Usage-based Value+ services include fees for electronic payment processing, applicant screening services, our legal liability to landlord insurance program, collections, online vacancy advertising services and renters insurance. Usage-based fees are charged on a flat fee per transaction basis with no minimum usage commitments. We recognize revenue for usage-based services in the period the service is rendered. We generally invoice our customers for usage-based services on a monthly basis for services rendered in the preceding month with the exception of fees for electronic payment processing, which are generally paid by the clients of our customers at the time the electronic payment is processed. Revenue from Value+ services is impacted by a number of factors, including the number of new and existing customers that adopt and utilize our Value+ service, the size and needs of our customers and our customer renewal rates.

Other revenue includes revenue from one-time services related to on-boarding customers to our core solutions, website design services and online vacancy advertising services offered to legacy RentLinx customers.

Our legal software core solution offers customers a free trial period to try our software. Revenue is not recognized until the free trial period is complete and the customer has entered into a subscription agreement with us.

Our customers do not have rights to the underlying software code of our solutions, and accordingly, the Company's revenue arrangements are outside the scope of the software revenue recognition guidance, and are instead recognized in accordance with Staff Accounting Bulletin Topic 13. We recognize revenue when (i) there is persuasive evidence of an arrangement, (ii) our software solutions have been made available or delivered, or services have been performed, (iii) the amount of fees is fixed or determinable, and (iv) collectability is reasonably assured. Evidence of an arrangement generally consists of either a signed customer contract or an online click-through agreement. We consider that delivery of a solution or website has commenced once we provide the customer with access to use the solution or website. Fees are fixed based on rates specified in the subscription agreements, which do not provide for any refunds or adjustments. If collectability is not considered reasonably assured, revenue is deferred until the fees are collected. Some of our subscription agreements contain minimum cancellation fees in the event that the customer cancels the subscription early.

For multiple-deliverable arrangements, we first assess whether each deliverable has value to the customer on a standalone basis. We have determined that the subscription services related to our core solutions have value on a standalone basis because once access is provided, they are fully functional and do not require additional development, modification or customization. Our Value+ services have value on a standalone basis as the services are sold separately by other vendors and are not essential to the functionality of the other deliverables. The usage-based services are typically entered into subsequent to the initial customer arrangement. In multiple-deliverable arrangements that contain usage-based services, the customer has the option to purchase the services on an ad hoc basis, and payments are made when the services are rendered.

Based on the standalone value of the deliverables, and since our customers do not have a general right of return, we allocate revenue among the separate non-contingent deliverables in a multiple-deliverable arrangement under the relative selling price method using the selling price hierarchy within the revenue accounting guidance (ASC Topic 605, Revenue Recognition). The selling price hierarchy requires the selling price of each deliverable in a multiple-deliverable arrangement to be based on, in descending order, (i) vendor-specific objective evidence of fair value ("VSOE"), (ii) third-party evidence of fair value ("TPE"), or (iii) management’s best estimate of the selling price ("BESP").

For our property manager core solution, we have established VSOE based on our consistent historical pricing and discounting practices for customer renewals where the customer only subscribes to our core solutions, and based on the price established by management for elements not yet being sold separately. In establishing VSOE, the substantial majority of the selling prices for our core solutions fall within a reasonably narrow pricing range, and the price once established by management for elements not yet being sold separately are not offered at a discount. For our legal software core solution, we utilize BESP to allocate revenue among the separate non-contingent deliverables, as we have been unable to establish VSOE due to our discounting practices, and we have been unable to obtain TPE.

After the contract value is allocated to each non-contingent deliverable in a multiple-deliverable arrangement based on the relative selling price, revenue is recognized for each deliverable based on the pattern in which the revenue is earned. For subscriptions services, revenue is recognized on a straight-line basis over the subscription period. For usage-based services, revenue is recognized as the services are rendered. For one-time services, revenue is recognized upon completion of the related services. Sales commissions and other incremental costs to acquire contracts are expensed as incurred.

Cost of Revenue

Cost of revenue consists of fees paid to third-party service providers, personnel-related costs (including salaries, incentive-based compensation, benefits, and stock-based compensation) for our employees focused on customer service and the support of our operations, platform infrastructure costs (such as data center operations and hosting-related costs), payment processing fees, and allocated shared costs. We typically allocate shared costs across our organization based on headcount within the applicable part of our organization. Cost of revenue excludes depreciation of property and equipment, and amortization of capitalized software development costs and intangible assets.

Sales and Marketing

Sales and marketing expense consists of personnel-related costs (including salaries, sales commissions, incentive-based compensation, benefits, and stock-based compensation) for our employees focused on sales and marketing, costs associated with sales and marketing activities, and allocated shared costs. Marketing activities include advertising, online lead generation, lead nurturing, customer and industry events, and the creation of industry-related content and collateral. Sales commissions and other incremental costs to acquire customers and grow adoption and utilization of our Value+ services by new and existing customers are expensed as incurred. We focus our sales and marketing efforts on generating awareness of our software solutions, creating sales leads, establishing and promoting our brands, and cultivating an educated community of successful and vocal customers. Advertising expenses were $3.6 million for each of the years ended December 31, 2017, 2016 and 2015, respectively, and are expensed as incurred.

Research and Product Development

Research and product development expense consists of personnel-related costs (including salaries, incentive-based compensation, benefits, and stock-based compensation) for our employees focused on research and product development, fees for third-party development resources, and allocated shared costs. Our research and product development efforts are focused on enhancing the ease of use and functionality of our existing software solutions by adding new core functionality, Value+ services and other improvements, as well as developing new products and services. We capitalize the portion of our software development costs that meets the criteria for capitalization. Amortization of capitalized software development costs is included in depreciation and amortization expense.

General and Administrative

General and administrative expense consists of personnel-related costs (including salaries, incentive-based compensation, benefits, and stock-based compensation) for employees in our executive, finance, information technology, human resources, corporate development, legal and administrative organizations. In addition, general and administrative expense includes fees for third-party professional services (including audit, legal, tax, and consulting services), other corporate expenses, and allocated shared costs.

Depreciation and Amortization

Depreciation and amortization expense includes depreciation of property and equipment, amortization of capitalized software development costs and amortization of intangible assets. We depreciate or amortize property and equipment, software development costs and intangible assets over their expected useful lives on a straight-line basis, which approximates the pattern in which the economic benefits of the assets are consumed.

Stock-Based Compensation

We account for stock-based compensation awards granted to employees and directors by recording compensation expense based on each award's grant-date estimated fair value, in accordance with ASC 718, Compensation-Stock Compensation over the vesting period. We estimate the fair value of restricted stock awards ("RSAs"), restricted stock units ("RSUs") and performance based RSUs ("PSUs") based on the fair value of our common stock on the date of grant. We estimate the fair value of stock options and performance based stock options ("PSOs") using the Black-Scholes option-pricing model. Determining the fair value of stock options under this model requires highly subjective assumptions, including the fair value of the underlying common stock, the risk-free interest rate, the expected term of the award, the expected volatility of the price of our common stock, and the expected dividend yield of our common stock. These estimates involve inherent uncertainties and the application of management’s judgment. If we had made different assumptions, our stock-based compensation expense could have been materially different.

Since our IPO in June 2015, the fair value of our common stock is based on the closing price of our Class A common stock, as quoted on the NASDAQ Global Market, on the date of grant and we utilized the following assumptions and estimates when utilizing the Black-Scholes option-pricing model when calculating the fair value of our options and PSOs:


▪	Risk-Free Interest Rate - The risk free interest rate assumption is based upon observed interest rates on United States government securities appropriate for the expected term of the stock option.


▪	Expected Term - Given that we do not have sufficient exercise history to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior, we determine the expected term using the simplified method, which is calculated as the midpoint of the stock option vesting term and the expiration date of the stock option.

▪

Expected Volatility - We determine the expected volatility based on the historical average volatilities of publicly traded industry peers. We intend to continue to consistently apply this methodology using the same or similar public companies until a sufficient amount of historical information regarding the volatility of our own common stock price becomes available, unless circumstances change such that the identified companies are no longer similar to us, in which case, more suitable companies whose stock prices are publicly available would be utilized in the calculation.


▪	Expected Dividend Yield - We have not paid and do not anticipate paying any cash dividends in the foreseeable future and, therefore, we use an expected dividend yield of zero.

Forfeiture Rate

In addition to the assumptions used in the Black-Scholes option-pricing model, we also estimate a forfeiture rate to calculate our stock-based compensation expense for our options and awards. The forfeiture rate is based on an analysis of actual forfeitures. We will continue to evaluate the appropriateness of the forfeiture rate based on actual forfeiture experience, analysis of employee turnover, and other factors. Changes in the estimated forfeiture rate can have a significant impact on our stock-based compensation expense as the cumulative effect of adjusting the rate is recognized in the period the estimated forfeiture rate is changed. If a revised forfeiture rate is higher than the previously-estimated forfeiture rate, an adjustment is made that will result in a decrease to our stock-based compensation expense recognized in our consolidated financial statements. If a revised forfeiture rate is lower than the previously-estimated forfeiture rate, an adjustment is made that will result in an increase to our stock-based compensation expense recognized in our consolidated financial statements.

Restricted Stock Units

In September 2015, we began granting RSUs. The RSUs vest in equal tranches over four annual periods and are expensed on a straight-line basis over the vesting period. The shares underlying the RSU grants are not issued and outstanding until the applicable vesting date.

Performance Based Equity Awards

In 2016, we began granting PSOs and PSUs. The fair values of the PSOs are estimated using the Black-Scholes option-pricing model and the PSUs fair values are based on the fair value of our common stock on the date of grant. The vesting of the PSOs and PSUs is based on achievement of a pre-established free cash flow performance metric or adjusted gross margin target and continued employment throughout the performance period. We recognize expense for the PSOs and PSUs based on the grant date fair value to the extent vesting of the award is probable. Adjustments to compensation expense are made each period based on changes in our estimate of the number of PSOs and PSUs that are probable of vesting. PSOs and PSUs will vest upon achievement of the relevant performance metric once such calculation is reviewed and approved by our board of directors.

Income Taxes

We account for income taxes in accordance with ASC 740, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the carrying amounts and the tax bases of assets and liabilities. Deferred income tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the consolidated statements of operations in the period that includes the enactment date. A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized.

We recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in our consolidated financial statements from such positions are then measured based on the largest benefit that has a greater than 50% likelihood of being realized. We recognize interest and penalties accrued with respect to uncertain tax positions, if any, in our provision for income taxes in the consolidated statements of operations.

Net Income (Loss) per Share

The net income (loss) per common share was the same for our Class A and Class B common shares because they are entitled to the same liquidation and dividend rights and are therefore combined in the table below. The following table presents a reconciliation of our weighted average number of Class A and Class B common shares used to compute net income (loss) per share (in thousands):



	Year Ended December 31,
	2017	2016	2015
Weighted average common shares outstanding	33,876	33,639	21,486
Less: Weighted average unvested restricted shares subject to repurchase	27	78	150
Weighted average common shares outstanding; basic	33,849	33,561	21,336

Weighted average common shares outstanding; basic	33,849	33,561	21,336
Plus: Weighted average options, RSUs and restricted shares used to compute diluted net income per share	1,302	—	—
Weighted average common shares outstanding; diluted	35,151	33,561	21,336

Approximately 548,000 shares of PSOs and PSUs are not included in the computations of diluted and anti-dilutive shares for the year ended December 31, 2017, as they are considered contingently issuable upon the satisfaction of pre-defined performance measures and their respective performance measures have not been met.

For the years ended December 31, 2016 and 2015, we reported a net loss and therefore all potentially dilutive common shares are anti-dilutive and have been excluded from the calculation of net loss per share. The following table presents the number of anti-dilutive common shares excluded from the calculation of weighted average number of shares used to compute diluted net income (loss) per share for the years ended December 31, 2017, 2016, and 2015 (in thousands):



	December 31,
	2017	2016	2015
Options to purchase common stock	—	1,718	1,171
Unvested RSAs	—	46	120
Unvested RSUs	21	496	17
Contingent RSUs⁽¹⁾	6	34	49
Total shares excluded from net loss per share attributable to common stockholders	27	2,294	1,357

⁽¹⁾The reported shares are based on fixed price RSU commitments for which the number of shares has not been determined at the grant date. The number of shares have been determined by dividing the fixed price commitment to issue shares in the future by the closing price of our common stock as of the applicable reporting period date.

Recently Adopted Accounting Pronouncements

Under the Jumpstart our Business Startups Act (the “JOBS Act”), we meet the definition of an emerging growth company. We have irrevocably elected to opt out of the extended transition period for complying with new or revised accounting standards pursuant to Section 107(b) of the JOBS Act.

In March 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-09, Compensation - Stock Compensation (Topic 781), Improvements to Employee Share-Based Payment Accounting ("ASU 2016-09"), which amends and simplifies the accounting for share-based payment awards in three areas: (i) income tax consequences, (ii) classification of awards as either equity or liabilities, and (iii) classification on the statement of cash flows. ASU 2016-09 also provides an accounting policy election to account for forfeitures as they occur. We adopted this guidance on January 1, 2017. The impact on the Company’s consolidated financial statements was not material due to the full valuation allowance on our deferred tax assets. We have elected to continue to estimate forfeitures expected to occur to determine the amount of compensation cost to be recognized each period.

Recent Accounting Pronouncements Not Yet Adopted

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, as amended, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers (the “new revenue standard”). The new revenue standard also includes Subtopic 340-40, Other Assets and Deferred Costs - Contracts with Customers, which discusses the deferral of incremental costs of obtaining a contract with a customer. The new revenue standard will be effective on January 1, 2018. The standard permits the use of either a full retrospective or modified retrospective transition method.

The Company will adopt the new revenue standard as of January 1, 2018, using the modified retrospective transition method applied to those contracts which were not completed as of that date. Upon adoption, we will recognize the cumulative effect of adopting this guidance as an adjustment to our opening balance of accumulated deficit. Prior periods will not be retrospectively adjusted.

We do not expect a material impact on our revenue upon adoption. The primary impact of adopting the new revenue standard relates to the deferral of incremental costs of obtaining contracts. We have substantially completed our assessment of the impacts of the new revenue standard on incremental costs of obtaining contracts and we expect to record an adjustment to decrease accumulated deficit as of January 1, 2018 for approximately $3.0 million related to the accounting for the cost of sales commissions. Historically, sales commissions and other incremental costs to obtain contracts are expensed as incurred. Under the new revenue standard, such costs will be deferred and recognized over the period of benefit which we have determined to be three years. The Company is in the process of implementing the necessary changes to its accounting policies, processes, internal controls and information systems that will be required to meet the new revenue standard’s reporting and disclosure requirements.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) ("ASU 2016-02"). Under ASU 2016-02, an entity will be required to recognize right-of-use assets and lease liabilities on its balance sheet and disclose key information about leasing arrangements. ASU 2016-02 offers specific accounting guidance for a lessee, a lessor and sale and leaseback transactions. Lessees and lessors are required to disclose qualitative and quantitative information about leasing arrangements to enable a user of the financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. For public companies, ASU 2016-02 is effective for annual reporting periods beginning after December 15, 2018, including interim periods within that reporting period, and requires a modified retrospective adoption, with early adoption permitted. There are additional optional practical expedients that an entity may elect to apply. We anticipate this standard will have a material impact on our consolidated financial statements. While we are continuing to assess all potential impacts of the standard, we currently believe the most significant impact relates to our accounting and reporting of our operating leases on our balance sheet. We are in the process of implementing changes to our processes in conjunction with our review of existing lease agreements. We will adopt ASU 2016-02 effective January 1, 2019 and expect to elect certain available transitional practical expedients.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ("ASU 2016-13"), which amends the current accounting guidance and requires the measurement of all expected losses based on historical experience, current conditions and reasonable and supportable forecasts. This guidance amends the accounting for credit losses for available-for-sale securities and purchased financial assets with credit deterioration. ASU 2016-13 is effective for annual periods beginning after December 15, 2019, and interim periods within those annual periods. Early adoption is permitted for any interim or annual period after December 15, 2018. We do not expect the adoption of this guidance to have a material impact on our financial condition, results of operations, cash flows or disclosures.

In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments ("ASU 2016-15"), which provides cash flow statement classification guidance for debt prepayment or debt extinguishment costs; settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing; contingent consideration payments made after a business combination; proceeds from the settlement of insurance claims; proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; distributions received from equity method investees; beneficial interests in securitization transactions; and separately identifiable cash flows and application of the predominance principle. ASU 2016-15 is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. We do not expect the adoption of this guidance to have a material impact on our statement of cash flows.

In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory ("ASU 2016-16"), which changes the timing of when certain intercompany transactions are recognized within the provision for income taxes. ASU 2016-16 is effective on January 1, 2018. Early adoption is permitted. We do not expect the adoption of this guidance to have a material impact on our financial condition, results of operations, cash flows or disclosures.

In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash ("ASU 2016-18"), which provides amendments to current guidance to address the classification and presentation of changes in restricted cash in the statement of cash flows. ASU 2016-18 is effective on January 1, 2018 and early adoption is permitted. We expect that adoption will change the current presentation of restricted cash on our statement of cash flows as well as require additional disclosures to reconcile cash and cash equivalents per the balance sheet to cash and cash equivalents on the statement of cash flows.

In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment ("ASU 2017-04"), which eliminates Step 2 from the goodwill impairment test. The annual, or interim, goodwill impairment test is performed by comparing the fair value of a reporting unit with its carrying amount. An impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. In addition, income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit should be considered when measuring the goodwill impairment loss, if applicable. ASU 2017-04 also eliminates the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails that qualitative test, to perform Step 2 of the goodwill impairment test. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. ASU 2017-04 is effective for public entities for fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on dates after January 1, 2017. We do not expect the adoption of this guidance to have a material impact on our financial condition, results of operations, cash flows or disclosures.

In March 2017, the FASB issued ASU No. 2017-08, Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20), Premium Amortization on Purchased Callable Debt Securities (“ASU 2017-08”). ASU 2017-08 shortens the amortization period for certain callable debt securities held at a premium. Specifically, ASU 2017-08 requires the premium to be amortized to the earliest call date. ASU 2017-08 does not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. For public companies, ASU 2017-08 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted, including adoption in an interim period. The amendments should be applied on a modified retrospective basis, with a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. We do not expect the adoption of this guidance to have a material impact on our financial condition, results of operations, cash flows or disclosures since our current accounting policy is in accordance with ASU 2017-08.

In May 2017, the FASB issued ASU 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting ("ASU 2017-09"). ASU 2017-09 clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. The new guidance will reduce diversity in practice and result in fewer changes to the terms of an award being accounted for as modifications. Under ASU 2017-09, an entity will not apply modification accounting to a share-based payment award if the award’s fair value, vesting conditions and classification as an equity or liability instrument are the same immediately before and after the change. ASU 2017-09 will be applied prospectively to awards modified on or after the adoption date. The guidance is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. Early adoption is permitted. We do not expect the adoption of this guidance to have a material impact on our financial condition, results of operations, cash flows or disclosures.

Investment Securities and Fair Value Measurements

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Investment Securities and Fair Value Measurements

Investment Securities

Investment securities classified as available-for-sale consisted of the following at December 31, 2017 and 2016 (in thousands):



	December 31, 2017
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Corporate bonds	$	38,383	$	—	$	(166	)	$	38,217
Agency securities	11,045		—		(42		)	11,003
Certificates of deposit	2,982		1		(2		)	2,981
Total available-for-sale investment securities	$	52,410	$	1	$	(210	)	$	52,201



	December 31, 2016
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Corporate bonds	$	30,492	$	9	$	(56	)	$	30,445
Agency securities	6,248		—		(20		)	6,228
Certificates of deposit	5,472		16		—			5,488
Total available-for-sale investment securities	$	42,212	$	25	$	(76	)	$	42,161

As of December 31, 2017, the unrealized losses on investment securities which have been in a net loss position for twelve months or greater were not material. These unrealized losses are considered temporary and there were no impairments considered to be "other-than-temporary" based on our evaluation of available evidence, which includes our intent to hold these investments to maturity or a recovery of the cost basis.

At December 31, 2017 and 2016, the contractual maturities of our investments did not exceed 36 months. The fair values of available-for-sale investments, by remaining contractual maturity, are as follows (in thousands):



	December 31, 2017				December 31, 2016
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Due in 1 year or less	$	29,850	$	29,800	$	15,475	$	15,473
Due after 1 year through 3 years	22,560		22,401		26,737		26,688
Total available-for-sale investment securities	$	52,410	$	52,201	$	42,212	$	42,161

During the years ended December 31, 2017 and 2016, we had sales and maturities (which include calls) of investment securities, as follows (in thousands):



	Year Ended December 31, 2017
	Gross Realized Gains		Gross Realized Losses		Gross Proceeds from Sales		Gross Proceeds from Maturities
Corporate bonds	$	—	$	—	$	—	$	10,690
Agency securities	1		—		15		3,294
Certificates of deposit	—		—		—		2,490
	$	1	$	—	$	15	$	16,474



	Year Ended December 31, 2016
	Gross Realized Gains		Gross Realized Losses		Gross Proceeds from Sales		Gross Proceeds from Maturities
Corporate bonds	$	7	$	—	$	7,554	$	2,480
Agency securities	5		—		3,005		11,557
Certificates of deposit	—		—		—		1,245
Treasury bills	—		—		2,000		6,055
	$	12	$	—	$	12,559	$	21,337

For the years ended December 31, 2017, 2016 and 2015 we received interest income net of the amortization and accretion of the premium and discount of $0.7 million, $0.5 million, and $0.2 million, respectively.

Fair Value Measurements

Recurring Fair Value Measurements

Financial assets and financial liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following tables summarize our financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2017 and 2016, by level within the fair value hierarchy (in thousands):



	December 31, 2017
	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	5,524	$	—	$	—	$	5,524
Available-for-sale investment securities:
Corporate bonds	—		38,217		—		38,217
Agency securities	—		11,003		—		11,003
Certificates of deposit	2,981		—		—		2,981
Total Assets	$	8,505	$	49,220	$	—	$	57,725



	December 31, 2016
	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	4,849	$	—	$	—	$	4,849
Available-for-sale investment securities:
Corporate bonds	—		30,445		—		30,445
Agency securities	—		6,228		—		6,228
Certificates of deposit	5,488		—		—		5,488
Total Assets	$	10,337	$	36,673	$	—	$	47,010

The carrying amounts of cash equivalents, restricted cash, accounts receivable, accounts payable and accrued liabilities approximate fair value because of the short maturity of these items.

There were no changes to our valuation techniques used to measure asset and liability fair values on a recurring basis during the year ended December 31, 2017. The valuation techniques for the items in the table above are as follows:

Cash Equivalents

As of December 31, 2017 and 2016, cash equivalents include cash invested in money market funds. Fair value is based on market prices for identical assets.

Available-for-Sale Investment Securities

The fair value of our corporate bonds and agency securities is based on pricing determined using inputs other than quoted prices that are observable either directly or indirectly such as yield curve, volatility factors, credit spreads, default rates, loss severity, current market and contractual prices for the underlying instruments or debt, broker and dealer quotes, as well as other relevant economic measures. The fair value of our certificates of deposit is based on market prices for identical assets.

Non-Recurring Fair Value Measurements

Certain assets, including goodwill, intangible assets and our note receivable with SecureDocs, are also subject to measurement at fair value on a non-recurring basis using Level 3 measurement, but only when they are deemed to be impaired as a result of an impairment review. For the years ended December 31, 2017 and 2016, no impairments were identified on those assets required to be measured at fair value on a non-recurring basis.

Property and Equipment

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property and Equipment

Property and equipment consists of the following as of December 31, 2017 and 2016 (in thousands):



	December 31,
	2017			2016
Data center and computer equipment	$	5,233		$	4,913
Furniture and fixtures	2,415			2,465
Office equipment	763			726
Leasehold improvements	5,029			4,035
Gross property and equipment	13,440			12,139
Less: Accumulated depreciation	(6,744		)	(5,062		)
Total property and equipment, net	$	6,696		$	7,077

Depreciation expense for property and equipment totaled $2.3 million, $2.3 million, and $1.4 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Internal-Use Software Development Costs

12 Months Ended

Dec. 31, 2017

Research and Development [Abstract]

Internal-Use Software Development Costs

Internal-use software development costs were as follows (in thousands):



	December 31,
	2017			2016
Internal use software development costs, gross	$	44,626		$	33,545
Less: Accumulated amortization	(27,017		)	(18,006		)
Internal use software development costs, net	$	17,609		$	15,539

Capitalized software development costs were $11.1 million, $11.8 million and $8.0 million for the years ended December 31, 2017, 2016 and 2015, respectively. Amortization expense with respect to software development costs totaled $9.0 million, $6.2 million and $3.5 million for the years ended December 31, 2017, 2016, and 2015, respectively.

Future amortization expense with respect to capitalized software development costs as of December 31, 2017 is estimated as follows (in thousands):



Years Ending December 31,
2018	$	9,309
2019	6,061
2020	2,210
2021	29
Total amortization expense	$	17,609

Intangible Assets

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets

Intangible assets consisted of the following as of December 31, 2017 and 2016 (in thousands, except years):



	December 31, 2017
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Weighted Average Useful Life in Years
Customer relationships	$	790	$	(538	)	$	252	5.0
Technology	4,811		(3,871		)	940		6.0
Trademarks	930		(539		)	391		9.0
Partner relationships	680		(623		)	57		3.0
Non-compete agreements	40		(37		)	3		3.0
Domain names	273		(273		)	—		5.0
Patents	285		(203		)	82		5.0
	$	7,809	$	(6,084	)	$	1,725	5.9



	December 31, 2016
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Weighted Average Useful Life in Years
Customer relationships	$	790	$	(392	)	$	398	5.0
Technology	4,811		(3,070		)	1,741		6.0
Trademarks	930		(416		)	514		9.0
Partner relationships	680		(397		)	283		3.0
Non-compete agreements	40		(23		)	17		3.0
Domain names	273		(241		)	32		5.0
Patents	284		(164		)	120		5.0
	$	7,808	$	(4,703	)	$	3,105	5.9

Amortization expense totaled $1.4 million, $1.4 million and $1.3 million for the years ended December 31, 2017, 2016 and 2015, respectively. Amortization expense for each of the five fiscal years through December 31, 2022 is estimated as follows (in thousands):



Years Ending December 31,
2018	$	929
2019	352
2020	259
2021	124
2022	61
Total amortization expense	$	1,725

Long-term Debt	12 Months Ended
Long-term Debt	Dec. 31, 2017
Debt Disclosure [Abstract]
Long-term Debt	Long-term Debt Credit Agreement On March 16, 2015, we entered into a credit facility (the “Original Credit Agreement”) comprised of a $10.0 million term loan (the “Term Loan”), and a $2.5 million revolving line of credit (the "Original Revolving Facility") with Wells Fargo, as administrative agent, and the lenders that are parties thereto ("Wells Fargo"). In March 2015, we borrowed $10.0 million under the Term Loan and on July 16, 2015, we made an optional prepayment in full of the Term Loan. On October 9, 2015, we entered into Amendment Number One to the Original Credit Agreement, which amended the terms of the Original Credit Agreement with Wells Fargo (as amended, the “Credit Agreement”). Under the terms of the Credit Agreement, the lenders made available to us a $25.0 million revolving line of credit (the “Revolving Facility”). Subject to customary terms and conditions, we can seek to increase the principal amount of indebtedness available under the Credit Agreement by up to $10.0 million, in the form of revolving commitments or term loan debt, although the lenders are under no obligation to make additional amounts available to us. Borrowings under the Revolving Facility are subject to the satisfaction of customary conditions. Borrowings under the Revolving Facility bear interest at a fluctuating rate per annum equal to, at our option, (i) a base rate equal to the highest of (a) the federal funds rate plus 1/2 of 1%, (b) the London Interbank Offered Rate (“LIBOR”) for a one-month interest period plus 1% and (c) the rate of interest in effect for such day as publicly announced from time to time by Wells Fargo as its prime rate, in each case plus an applicable margin of 1.5%, or (ii) LIBOR for the applicable interest period plus an applicable margin of 2.5%. Interest is due and payable monthly. We are also required to pay a commitment fee equal to 0.25% per annum of the unused portion of the Revolving Facility if revolver usage is above $10.0 million, or 0.375% per annum of the unused portion of the Revolving Facility if revolver usage is less than or equal to $10.0 million. The Revolving Facility matures on October 9, 2020; however, we can make payments on the Revolving Facility, and cancel it in full at any time without premium or penalty. The Credit Agreement contains customary affirmative, negative and financial covenants. The affirmative covenants require us to, among other things, disclose financial and other information to the lenders, maintain our business and properties, and maintain adequate insurance. The negative covenants restrict us from, among other things, incurring additional indebtedness, prepaying certain types of indebtedness, encumbering or disposing of our assets, making fundamental changes to our corporate structure, and making certain dividends and distributions. The financial covenants require us to maintain liquidity of not less than $12.5 million and, to the extent liquidity is determined to be below $25.0 million, to comply with a maximum senior leverage ratio. At December 31, 2017, we were in compliance with the financial covenants of the Credit Agreement. As of December 31, 2017 and 2016, there was no outstanding balance under the Credit Agreement. Debt Financing Costs Debt financing costs are deferred and amortized, using the straight-line method for costs related to the Revolving Facility. In conjunction with the amendment to our Credit Agreement for the Revolving Facility, we incurred costs to process the amendment and we capitalized additional costs of $0.2 million. These additional costs were added to the unamortized debt financing costs from the Original Revolving Facility of $0.1 million and are amortized using a straight-line method over the term of the Revolving Facility's commitment within interest expense. The total unamortized debt financing costs for the amended Revolving Facility of $0.2 million at December 31, 2017 and 2016 were recorded in other assets. In 2015, we incurred fees to Wells Fargo attributable to the Term Loan of $0.3 million and other third-party debt financing costs of $0.1 million, which were recorded as a reduction of the carrying amount of the Term Loan. Amortization of such costs was included in interest expense. When the Term Loan was repaid prior to the maturity date, the unamortized debt financing costs related to the Term Loan of $0.4 million were expensed as interest expense. Total interest expense for the year ended December 31, 2015 was $0.8 million.

Commitment and Contingencies

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Lease Obligations

As of December 31, 2017, we had operating lease obligations of approximately $9.1 million through 2022. A summary of our future minimum payments for obligations under non-cancellable operating leases is as follows (in thousands):



Years Ending December 31,
2018	$	2,446
2019	2,509
2020	2,512
2021	1,483
2022	179
Total lease commitments	$	9,129

We recorded rent expense of $2.1 million, $2.0 million and $1.2 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Insurance

We have a wholly owned subsidiary, Terra Mar Insurance Company, Inc., which was established to provide our customers with the option to purchase legal liability to landlord insurance. If our customers choose to use our insurance services, they are issued an insurance policy underwritten by our third-party service provider. The policy has a limit of $100,000 per incident for each insured residence. We have entered into a reinsurance agreement with our third-party service provider and, as a result, we assume a 100% quota share of the legal liability to landlord insurance provided to our customers through our third-party service provider. Included in cost of revenue we accrue for reported claims and an estimate of losses incurred but not reported by our property manager customers, as we bear the risk related to claims. Our liability for reported claims and incurred but not reported claims as of December 31, 2017 and 2016 was $0.5 million and $0.3 million, respectively, and is included in other current liabilities on the Consolidated Balance Sheets.

Included in other current assets as of December 31, 2017 and 2016 are $1.8 million and $1.2 million, respectively, of deposits held with a third party related to requirements to maintain collateral for our insurance services.

Litigation

From time to time, we may become subject to certain legal proceedings, including without limitation claims and/or litigation matters, arising in the ordinary course of business. We are not currently a party to any such legal proceedings, nor are we aware of any pending or threatened litigation, that would have a material adverse effect on our business, operating results, cash flows or financial condition should such litigation be resolved unfavorably.

Indemnification

In the ordinary course of business, we may provide indemnification of varying scope and terms to customers, investors, directors and officers with respect to certain matters, including, but not limited to, losses arising out of our breach of any applicable agreements, services to be provided by us, or intellectual property infringement claims made by third parties. These indemnification provisions may survive termination of the underlying agreement and the maximum potential amount of future payments we could be required to make under these indemnification provisions may not be subject to maximum loss clauses. The maximum potential amount of future payments we could be required to make under these indemnification provisions is indeterminable. We have never paid a material claim, nor have any legal claims been brought against us, in connection with these indemnification arrangements. As of December 31, 2017 and 2016, we had not accrued a liability for these indemnification arrangements because we determined that the likelihood of incurring a payment obligation, if any, in connection with these indemnification arrangements is not probable or reasonably possible, and the amount or range of amounts of any such liability is not reasonably estimable.

Stockholders' Equity	12 Months Ended
Stockholders' Equity	Dec. 31, 2017
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Amended and Restated Certificate of Incorporation Upon the effectiveness of the Amended and Restated Certificate of Incorporation of the Company on June 25, 2015, the number of shares of capital stock that is authorized to be issued was increased to 325,000,000 shares, of which 250,000,000 shares are Class A common stock, 50,000,000 shares are Class B common stock and 25,000,000 are undesignated preferred stock. The Class A common stock, Class B common stock and preferred stock have a par value of $0.0001 per share. At December 31, 2017, there were 14,879,000 shares of Class A common stock outstanding, 19,102,000 shares of Class B common stock outstanding and no preferred shares outstanding. Class A Common Stock and Class B Common Stock Except for voting rights, or as otherwise required by applicable law, the shares of our Class A common stock and Class B common stock have the same powers, preferences and rights and rank equally, share ratably and are identical in all respects as to all matters. The rights and preferences are as follows: Dividend Rights. Subject to preferences that may apply to any shares of preferred stock outstanding at the time, the holders of outstanding shares of our Class A common stock and Class B common stock are entitled to receive dividends out of funds legally available at the times and in the amounts that our board of directors may determine. Voting Rights. The holders of our Class A common stock are entitled to one vote per share, and holders of our Class B common stock are entitled to 10 votes per share. The holders of our Class A common stock and Class B common stock will vote together as a single class on all matters submitted to a vote of our stockholders, unless otherwise required by Delaware law or our amended and restated certificate of incorporation. Delaware law could require either holders of our Class A common stock or holders of our Class B common stock to vote separately. In addition, our amended and restated certificate of incorporation requires the approval of the holders of at least a majority of the outstanding shares of our Class B common stock, voting as a separate class to approve a change-in-control transaction. Conversion. Upon the closing of our initial public offering ("IPO"), all shares of our convertible preferred stock and common stock held prior to the offering were converted into shares of Class B common stock. Currently, each share of our Class B common stock is convertible at any time at the option of the holder into one share of our Class A common stock. In addition, each share of our Class B common stock will convert into one share of our Class A common stock upon any transfer, whether or not for value, except for certain transfers described in our amended and restated certificate of incorporation, including, without limitation, (i) a transfer by a partnership or limited liability company that was a registered holder of our Class B common stock at the “effective time,” as defined in our amended and restated certificate of incorporation, to a partner or member thereof at the effective time or (ii) a transfer to a “qualified recipient,” as defined in our amended and restated certificate of incorporation. All the outstanding shares of our Class B common stock will convert automatically into shares of our Class A common stock upon the date when the number of outstanding shares of our Class B common stock represents less than 10% of all outstanding shares of our Class A common stock and Class B common stock. Once converted into our Class A common stock, our Class B common stock may not be reissued. Right to Receive Liquidation Distributions. Upon our dissolution, liquidation or winding-up, the assets legally available for distribution to our stockholders are distributable ratably among the holders of our Class A common stock and Class B common stock, subject to prior satisfaction of all outstanding debt and liabilities and the preferential rights and payment of liquidation preferences, if any, on any outstanding shares of preferred stock. Preferred Stock Effective upon the filing of our amended and restated certificate of incorporation in June 2015, no shares of preferred stock were outstanding because all outstanding shares of our convertible preferred stock converted into our Class B common stock. Pursuant to the terms of our amended and restated certificate of incorporation, our board of directors will be authorized, subject to limitations prescribed by Delaware law, to issue up to 25,000,000 shares of our preferred stock in one or more series, to establish from time to time the number of shares to be included in each series, and to fix the designation, powers, preferences and rights of the shares of each series and any of its qualifications, limitations or restrictions, in each case without further action by our stockholders. The number of authorized shares of any series of preferred stock may be increased or decreased, but not below the number of shares of that series then outstanding, by the affirmative vote of the holders of a majority of the voting power of our outstanding capital stock entitled to vote thereon, or such other vote as may be required by the certificate of designation establishing the series. Convertible Preferred Stock Prior to IPO Up until our IPO, we had authorized preferred stock consisting of Series A convertible preferred stock, Series B convertible preferred stock, Series B-1 convertible preferred stock, Series B-2 convertible preferred stock and Series B-3 convertible preferred stock (collectively the “preferred stock prior to IPO”). Each preferred stockholder was entitled to the number of votes equal to the number of shares of common stock into which each preferred share was convertible at the time of such vote. The preferred stock was also entitled to receive non-cumulative dividends, when and if declared by our board of directors. No dividends were declared by our board of directors. In the event of a liquidation, the preferred stock was entitled to receive prior to payment of any amounts to the common stockholders the greater of (i) the original issuance price plus any declared but unpaid dividends or (ii) such amount per share as would have been payable had all shares of preferred stock been converted into common stock immediately prior to such liquidation, dissolution or winding up. The preferred stock was convertible into common stock at the option of the holder or automatically upon a qualified initial public offering. The preferred stock automatically converted to Class B common upon the Company's initial public offering. The liquidation preference provisions of the convertible preferred stock prior to IPO are considered contingent redemption provisions because there are certain elements that were not solely within our control, such as a change in control. Accordingly, we presented the convertible preferred stock prior to IPO within the mezzanine portion of the consolidated balance sheets.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

Stock Options

2015 Stock Incentive Plan

In conjunction with our IPO in 2015, our board of directors and stockholders adopted the 2015 Stock Incentive Plan (the "2015 Plan"). Upon adoption of the 2015 Plan, 2,000,000 shares of our Class A common stock were reserved and available for grant and issuance. On January 1 of each subsequent calendar year, the number of shares available for grant and issuance under the 2015 Plan increase by the lesser of (i) the number of shares of our Class A common stock subject to awards granted under the 2015 Plan during the preceding calendar year and (ii) such lesser number of shares of our Class A common stock determined by our board of directors. As of December 31, 2017, we have reserved an aggregate of 3,441,355 shares of our Class A common stock for grant and issuance under the 2015 Plan. The number of shares of our Class A common stock is also subject to adjustment in the event of a recapitalization, stock split, reclassification, stock dividend or other change in our capitalization. The 2015 Plan authorizes the award of stock options, stock appreciation rights, RSAs, RSUs, performance awards and stock bonuses. The 2015 Plan provides for the grant of awards to our employees, directors, consultants and independent contractors, subject to certain exceptions. RSUs, PSUs, PSOs, and RSAs have been issued during 2017 pursuant to the 2015 Plan.

Stock options may vest based on the passage of time or the achievement of performance conditions at the discretion of our compensation committee. Our compensation committee may provide for stock options to be exercised only as they vest or to be immediately exercisable with any shares issued on exercise being subject to our right of repurchase that lapses as the shares vest. The maximum term of stock options granted under the 2015 Plan is 10 years. We began granting stock options with performance conditions in 2016.

RSUs and PSUs represent the right on the part of the holder to receive shares of our Class A common stock at a specified date in the future or the achievement of performance conditions at the discretion of our compensation committee, subject to forfeiture of that right due to termination of employment. If an RSU or PSU has not been forfeited, then, on the specified date, we will deliver to the holder of the RSU or PSU shares of our Class A common stock.

2007 Stock Incentive Plan

On February 14, 2007, our board of directors adopted the 2007 Stock Incentive Plan (the “2007 Plan”) as an amendment and restatement to an original 2006 Equity Incentive Plan and was most recently amended in July 2014. Following our IPO, our board of directors determined not to make any further awards under the 2007 Plan. The 2007 Plan will continue to govern outstanding awards granted under the 2007 Plan. As of December 31, 2017, options to purchase an aggregate of 677,417 shares of our Class B common stock remained outstanding under the 2007 Plan. The 2007 Plan is administered by our board of directors, which determines the terms and conditions of each grant. Employees, officers, directors and consultants are eligible to receive stock options and stock awards under the 2007 Plan. The aggregate number of shares available under the 2007 Plan and the number of shares subject to outstanding options automatically adjusts for any changes in the outstanding common stock by reason of any recapitalization, spin-off, reorganization, reclassification, stock dividend, stock split, reverse stock split, or similar transaction. The exercise price of incentive stock options may not be less than the fair value of our common stock at the date of grant. The exercise price of incentive stock options granted to individuals that own greater than 10% of our voting stock may not be less than 110% of the fair value of our common stock at the date of grant. The term of each stock option cannot exceed ten years. Our board of directors will determine the vesting terms of all stock options. Generally, our board of directors has granted options with vesting terms of four years and contractual terms of ten years.

A summary of our stock option activity for the year ended December 31, 2017 is as follows (number of shares in thousands):



	Number of Shares		Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Life in Years
Options outstanding as of December 31, 2016	1,718		$	8.75	8.2
Options granted	172		24.77
Options exercised	(165	)	4.02
Options cancelled/forfeited	(33	)	10.17
Options outstanding as of December 31, 2017	1,692		$	10.81	7.3

As of December 31, 2017:
Options vested or expected to vest	1,688		$	10.82	7.3
Options exercisable⁽¹⁾	830		$	7.22	6.4

⁽¹⁾Included in the options exercisable is 65,000 shares which have an early exercise option. The weighted average exercise price of these options is $5.64 per share and the weighted average contractual life in years is 7.1 years.

During the year ended December 31, 2017, we granted PSOs to purchase up to 172,000 shares of our Class A common stock. The PSOs have a weighted average exercise price of $24.77 per share. Vesting of the PSOs is based on the achievement of pre-established performance metrics for the year ended December 31, 2019, and continued employment throughout the performance period. Of the PSOs granted during 2017, 132,000 shares would vest based upon the maximum payout of 100% when the 2019 free cash flow performance metric meets the maximum achievement of 150%. For performance at 100% of the targeted 2019 free cash flow metric, approximately 61% of the PSOs would vest. For performance at 80% of the targeted metric, approximately 48% of the PSOs would vest. For performance below 80% of the 2019 targeted metric, no PSOs would vest, all previously recognized compensation expense for the PSOs would be reversed, and no compensation expense would be recognized. The remaining 40,000 PSOs granted during 2017 have a pre-established adjusted gross margin target for 2019. PSOs tied to the gross margin performance metric have two levels of vesting, with 50% vesting based upon the achievement of 110% of the targeted amount and the remaining 50% vesting upon the achievement of 115% of the targeted amount. If the 110% performance target is not met, no shares would vest and all previously recognized expense for those PSOs would be reversed and no compensation expense would be recognized.

Included in the options outstanding as of December 31, 2017 are 500,000 PSOs granted in 2016, which vest based on the achievement of a pre-established free cash flow performance metric for the years ended December 31, 2017 and 2018. The number of PSOs granted in 2016 related to the performance metrics for the years ended December 31, 2017 and 2018, assumes achievement of the performance metric at the maximum level, which is 150% of the targeted performance metric. For performance at 100% of the targeted metric, approximately 67% of the PSOs would vest. For performance at 80% of the targeted metric, approximately 53% would vest. For performance below 50% of the 2017 targeted metric or 80% of the 2018 targeted metric, no PSOs would vest, all previously recognized compensation expense for PSOs would be reversed, and no compensation expense would be recognized.

During the year ended December 31, 2017, 247,000 of the PSOs vested based on the achievement of 148% of the pre-established free cash flow performance metric for the year ended December 31, 2016, and 3,000 PSOs were cancelled as a result of the PSOs being granted at 150% of the target metric. During the year ended December 31, 2016, $1.0 million of expense was recognized related to the PSOs that vested during the year ended December 31, 2017.

We recognize expense for the PSOs based on the grant date fair value of the PSOs that we determine are probable of vesting. Adjustments to compensation expense are made each period based on changes in our estimate of the number of PSOs that are probable of vesting.

Our stock-based compensation expense for stock options for the years ended December 31, 2017, 2016 and 2015 was $2.9 million, $2.4 million, and $0.7 million, respectively.

The fair value of stock options granted is estimated on the date of grant using the Black-Scholes option-pricing model. The following table summarizes information relating to our stock options granted during the years ended December 31, 2017, 2016 and 2015:



	Year Ended December 31,
	2017			2016			2015
Stock options granted (in thousands)	172			750			359
Weighted average exercise price per share	$	24.77		$	12.85		$	9.53
Weighted average grant-date fair value per share	$	9.58		$	4.85		$	6.89
Weighted average Black-Scholes model assumptions:
Risk-free interest rate	2.02		%	1.45		%	1.58		%
Expected term (in years)	6.4			5.9			6.2
Expected volatility	35		%	37		%	46		%
Expected dividend yield	—			—			—

As of December 31, 2017, the total remaining stock-based compensation expense for unvested stock options was $1.8 million, which is expected to be recognized over a weighted average period of 1.2 years.

The total intrinsic value of options exercised in 2017, 2016 and 2015 was $4.6 million, $1.9 million, and $3.1 million, respectively. This intrinsic value represents the difference between the fair value of our common stock on the date of exercise and the exercise price of each option. Based on the fair value of our common stock as of December 31, 2017, the total intrinsic value of all outstanding options was $51.9 million. The total intrinsic value of exercisable options as of December 31, 2017 was $28.4 million. The total intrinsic value of options vested and expected to vest as of December 31, 2017 was $51.8 million.

The excess tax benefit realized from option exercises during the year ended December 31, 2017 and 2016 was $5.2 million and $0.2 million, respectively. There were no excess tax benefits realized for the tax deductions from stock options exercised during the year ended December 31, 2015.

Restricted Stock Units

A summary of activity in connection with our RSUs for the year ended December 31, 2017 is as follows (number of shares in thousands):



	Number of Shares		Weighted- Average Grant Date Fair Value per Share
Unvested as of December 31, 2016	496		$	13.34
Granted	315		26.10
Vested	(150	)	13.31
Forfeited	(63	)	16.59
Unvested as of December 31, 2017	598		$	19.75

During the year ended December 31, 2017, we granted a total of 315,000 RSUs and PSUs: 202,000 RSUs vest annually over four years; 100,000 PSUs vest based upon achievement of a pre-established free cash flow performance metric for each of the years ended December 31, 2017, 2018, and 2019, and continued employment throughout the performance period; and 13,000 PSUs were granted and vested as a result of the attainment of the 2016 performance metric. The number of PSUs granted, as included in the above table, assumes achievement of the performance metric at 100% of the targeted performance metric. The actual number of shares to be issued at the end of the performance period will range from 0% to 165% of the initial target awards. For performance at 150% of the targeted metric, 150% to 165% of the PSUs would vest. For performance below 80% of the targeted metric, no PSUs would vest, no compensation expense would be recognized, and all previously recognized compensation expense for PSUs would be reversed.

During the year ended December 31, 2017, 41,000 of the PSUs vested based on the achievement of 148% of the pre-established free cash flow performance metric for the year ended December 31, 2016, and an additional 13,000 PSUs were granted and vested as a result of the attainment of the 2016 performance metric as approved by our board of directors. During the year ended December 31, 2016, $0.5 million of expense was recognized related to the PSUs that vested during the year ended December 31, 2017.

Included in the unvested RSUs and PSUs as of December 31, 2017 are 56,000 PSUs granted in 2016, which vest based on the achievement of a pre-established free cash flow performance metric for the years ended December 31, 2017 and 2018, and continued employment throughout the performance period. The number of PSUs granted in 2016 relates to the performance metrics for the years ended December 31, 2017 and 2018, and assumes achievement of the performance metric at 100% of the targeted performance metric. The actual number of shares to be issued at the end of the performance period will range from 0% to 150% of the initial target awards. For performance at 150% of the targeted metric, 150% of the PSUs would vest. For performance below 50% of the targeted metric for 2017 or 80% of the targeted metric for 2018, no PSUs would vest, no compensation expense would be recognized, and all previously recognized compensation expense for PSUs would be reversed.

We recognize expense for the PSUs based on the grant date fair value of the PSUs that we determine are probable of vesting. Adjustments to compensation expense are made each period based on changes in our estimate of the number of PSUs that are probable of vesting. Our stock-based compensation expense for the RSUs and PSUs for the years ended December 31, 2017, 2016, and 2015, was $3.6 million, $1.8 million and $0.1 million, respectively.

As of December 31, 2017, the total remaining stock-based compensation expense for these RSUs was $8.3 million, which is expected to be recognized over a weighted average period of 2.4 years.

Restricted Stock Awards

A summary of activity in connection with our RSAs for the year ended December 31, 2017 is as follows (number of shares in thousands):



	Number of Shares		Weighted- Average Grant Date Fair Value per Share
Unvested as of December 31, 2016	46		$	8.55
Granted	9		33.30
Vested	(39	)	9.24
Forfeited	—		—
Unvested as of December 31, 2017	16		$	20.93

We have the right to repurchase any unvested RSAs. RSAs vest over a four-year period for employees and over a one-year period for non-employee directors. For the years ended December 31, 2017, 2016 and 2015, we recognized stock-based compensation expense for RSAs of $358,000, $454,000 and $381,000, respectively. During 2017, the grant date fair value of the shares vested was $354,000.

As of December 31, 2017, the total remaining stock-based compensation expense for unvested RSAs was $0.2 million, which is expected to be recognized over a weighted average period of 0.6 years.

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

For the years ended December 31, 2017, 2016 and 2015, we recorded income tax expense of $58,000, $67,000, and $75,000, respectively, associated with state minimum taxes and the amortization of tax deductible goodwill that is not an available source of income to realize the deferred tax asset.

Our effective tax rate differs from the United States federal statutory rate of 34% primarily because our losses have been offset by a valuation allowance due to uncertainty as to the realization of the tax benefit of net operating losses ("NOLs". Set forth below is a reconciliation of the components that caused our provision for income taxes to differ from amounts computed by applying the United States federal statutory rate of 34% for the years ended December 31, 2017, 2016 and 2015:



	Year Ended December 31,
	2017		2016		2015
Income tax benefit at the statutory rate	34	%	34	%	34	%
State and local income taxes, net of federal benefit	(14	)	7		3
Stock-based compensation expense	(15	)	(4	)	(2	)
Meals and entertainment	2		(2	)	(1	)
Permanent differences	—		(1	)	—
Change in valuation allowance	(60	)	(42	)	(38	)
Change in federal rate	74		—		—
Research and development tax credits	(20	)	7		3
Provision for income taxes	1	%	(1	)%	(1	)%

The components of deferred tax assets (liabilities) were as follows (in thousands):



	December 31,
	2017			2016
Deferred income tax assets:
Net operating loss carryforwards	$	19,519		$	31,436
Research and development tax credits	8,278			4,032
Other	2,493			2,771
Gross deferred tax assets	30,290			38,239
Valuation allowance	(23,827		)	(29,417		)
Deferred tax assets, net of valuation allowance	6,463			8,822
Deferred tax liabilities:
Property, equipment and software	(4,293		)	(5,820		)
Intangible assets	(6		)	(403		)
State taxes	(1,693		)	(2,040		)
Other	(549		)	(632		)
Total deferred tax liabilities	(6,541		)	(8,895		)
Total net deferred tax liabilities	$	(78	)	$	(73	)

As of December 31, 2017, we had federal net operating loss carryforwards of $73.5 million, which will begin to expire in 2027. As of December 31, 2017, we had state net operating loss carryforwards of $48.0 million, which will begin to expire in 2023. As of December 31, 2017 we also had federal and state research and development credit carryforwards of $5.0 million and $5.4 million, respectively. The federal credit carryforwards will begin to expire in 2027, while the majority of the state credits carryforward indefinitely.

The Internal Revenue Code of 1986, as amended (“IRC”), imposes substantial restrictions on the utilization of NOLs and other tax attributes in the event of an “ownership change” of a corporation. Accordingly, a company’s ability to use pre-change NOLs and may be limited as prescribed under IRC Section 382. Events which may cause limitation in the amount of the NOLs and credits that we utilize in any one year include, but are not limited to, a cumulative ownership change of more than 50% over a three-year period. The Company has undertaken a NOL/382 analysis and has determined that there are no limitations on the NOL carryforwards at December 31, 2016.

Management assesses the available positive and negative evidence to estimate if sufficient future taxable income will be generated to use the existing deferred tax assets in the future. A significant piece of objective negative evidence evaluated was the cumulative loss incurred through December 31, 2017. Such objective evidence limits the ability to consider other subjective positive evidence such as current year taxable income and future income projections. On the basis of this evaluation, as of December 31, 2017, a valuation allowance of $23.8 million has been recorded since it is more likely than not that the deferred tax assets will not be realized.

The change in the valuation allowance for the years ended December 31, 2017, 2016 and 2015 was as follows (in thousands):



	Year Ended December 31,
	2017			2016		2015
Valuation allowance, at beginning of year	$	29,417		$	25,926	$	19,900
Increase (decrease) in valuation allowance	(5,590		)	3,491		6,026
Valuation allowance, at end of year	$	23,827		$	29,417	$	25,926

The following is a reconciliation of the total amounts of unrecognized tax benefits (in thousands):



	Year Ended December 31,
	2017			2016		2015
Unrecognized tax benefit beginning of year	$	4,032		$	2,867	$	2,014
Decreases-tax positions in prior year	(2,210		)	—		—
Increases-tax positions in current year	283			1,165		853
Unrecognized tax benefit end of year	$	2,105		$	4,032	$	2,867

The unrecognized tax benefits are recorded as a reduction to the deferred tax assets. Since there is a full valuation allowance recorded against the deferred tax assets, the recognition of previously unrecognized tax benefits on uncertain positions would result in no impact to the effective tax rate.

As of December 31, 2017 and 2016, we had no accrued interest and penalties related to uncertain income tax positions. We do not anticipate that the amount of unrecognized tax benefits will significantly increase or decrease within the next twelve months.

We are subject to taxation in the United States and various states. Due to the net operating loss carryforwards, the Company's federal and state returns are open to examination by the Internal Revenue Service and state jurisdictions for all years since inception. We are not currently under audit by any taxing authorities.

On December 22, 2017, the United States government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the "Tax Act"). The Tax Act significantly revises the existing tax law by, among other things, lowering the United States corporate income tax rate from 35% to 21% beginning in 2018. The Company reviewed and incorporated the impact of the Tax Act in its tax calculations and disclosures. The primary impact on the Company stems from the re-measurement of its deferred taxes at the new corporate tax rate of 21%, which reduced the Company's net deferred tax assets, before valuation allowance, by $7.2 million. Due to the full valuation allowance, the change in deferred taxes was fully offset by the change in valuation allowance, except for an immaterial amount that is reflected in income tax expense related to the rate re-measurement of the tax deductible goodwill. The Tax Act did not have a significant impact on the Company's Consolidated Financial Statements for the year ended December 31, 2017.

Revenue and Other Information

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Revenue and Other Information

The following table presents our revenue categories for the years ended December 31, 2017, 2016 and 2015 (in thousands):



	Year Ended December 31,
	2017		2016		2015
Core solutions	$	57,132	$	43,775	$	32,119
Value+ services	80,847		56,965		37,998
Other	5,824		4,846		4,860
Total revenues	$	143,803	$	105,586	$	74,977

Our revenue is generated primarily from United States customers. All of our property and equipment is located in the United States.

Retirement Plans	12 Months Ended
Retirement Plans	Dec. 31, 2017
Retirement Benefits [Abstract]
Retirement Plans	Retirement Plans We have a 401(k) retirement and savings plan made available to all employees. The 401(k) plan allows each participant to contribute up to an amount not to exceed an annual statutory maximum. We may, at our discretion, make matching contributions to the 401(k) plan. Cash contributions to the plan were $0.8 million and $1.1 million for the years ended December 31, 2017 and 2016. No cash contributions to the plan were made during the year ended December 31, 2015. Contribution expense recognized for the 401(k) plan was $0.8 million, $0.7 million, and $0.4 million for the years ended December 31, 2017, 2016, and 2015, respectively.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On February 20, 2018, our board of directors adopted a Long-Term Executive Cash Incentive Plan, pursuant to which it may grant performance awards (“Performance Awards”) that are intended to reward our executive officers for their individual contributions to our achievement of one or more long-term company performance goals and objectives over a specified period of time, and granted Performance Awards to Jason Randall, our Chief Executive Officer, and Ida Kane, our Chief Financial Officer (the “Recipients”). The Performance Awards are being granted in lieu of additional equity incentive awards to the Recipients.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Basis of Presentation and Significant Accounting Policies

The accompanying Consolidated Financial Statements were prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”).

Principles of Consolidation

Use of Estimates

Segment Information

Concentrations of Credit Risk

Concentrations of credit risk with respect to accounts receivable and revenue are limited due to a large, diverse customer base.

Fair Value Measurements

Level 1 - Quoted prices in active markets for identical assets or liabilities or funds.


	Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Cash and Cash Equivalents

Restricted Cash

Investment Securities

Accounts Receivable

Property and Equipment



Asset Type		Depreciation Period
Data center and computer equipment		3 years
Furniture and fixtures		7 years
Office equipment		2 to 5 years
Leasehold improvements		Shorter of remaining life of lease or asset life

Leases

Leases are evaluated and classified as either operating or capital leases. All of our office space leases are operating leases.

Internal-Use Software

Intangible Assets

Impairment of Long-Lived Assets

Business Combinations

Acquisition-related transaction costs are not included as a component of consideration transferred, but are accounted for as an operating expense in the period in which the costs are incurred.

General and Administrative

Research and Product Development

General and Administrative

Sales and Marketing

General and Administrative

Depreciation and Amortization

Stock-Based Compensation


▪	Risk-Free Interest Rate - The risk free interest rate assumption is based upon observed interest rates on United States government securities appropriate for the expected term of the stock option.


▪	Expected Term - Given that we do not have sufficient exercise history to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior, we determine the expected term using the simplified method, which is calculated as the midpoint of the stock option vesting term and the expiration date of the stock option.

▪


▪	Expected Dividend Yield - We have not paid and do not anticipate paying any cash dividends in the foreseeable future and, therefore, we use an expected dividend yield of zero.

Forfeiture Rate

Restricted Stock Units

Performance Based Equity Awards

Income Taxes

Recently Adopted Accounting Pronouncements and Recent Accounting Pronouncements Not Yet Adopted

Recently Adopted Accounting Pronouncements

Recent Accounting Pronouncements Not Yet Adopted

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Schedule of Estimated Useful Lives of Property and Equipment

The estimated useful lives of our property and equipment are as follows:



Asset Type		Depreciation Period
Data center and computer equipment		3 years
Furniture and fixtures		7 years
Office equipment		2 to 5 years
Leasehold improvements		Shorter of remaining life of lease or asset life

Property and equipment consists of the following as of December 31, 2017 and 2016 (in thousands):



	December 31,
	2017			2016
Data center and computer equipment	$	5,233		$	4,913
Furniture and fixtures	2,415			2,465
Office equipment	763			726
Leasehold improvements	5,029			4,035
Gross property and equipment	13,440			12,139
Less: Accumulated depreciation	(6,744		)	(5,062		)
Total property and equipment, net	$	6,696		$	7,077

Schedule of Weighted Average Number of Shares

The following table presents a reconciliation of our weighted average number of Class A and Class B common shares used to compute net income (loss) per share (in thousands):



	Year Ended December 31,
	2017	2016	2015
Weighted average common shares outstanding	33,876	33,639	21,486
Less: Weighted average unvested restricted shares subject to repurchase	27	78	150
Weighted average common shares outstanding; basic	33,849	33,561	21,336

Weighted average common shares outstanding; basic	33,849	33,561	21,336
Plus: Weighted average options, RSUs and restricted shares used to compute diluted net income per share	1,302	—	—
Weighted average common shares outstanding; diluted	35,151	33,561	21,336

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share

The following table presents the number of anti-dilutive common shares excluded from the calculation of weighted average number of shares used to compute diluted net income (loss) per share for the years ended December 31, 2017, 2016, and 2015 (in thousands):



	December 31,
	2017	2016	2015
Options to purchase common stock	—	1,718	1,171
Unvested RSAs	—	46	120
Unvested RSUs	21	496	17
Contingent RSUs⁽¹⁾	6	34	49
Total shares excluded from net loss per share attributable to common stockholders	27	2,294	1,357

Investment Securities and Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Schedule of Available-for-sale Securities

Investment securities classified as available-for-sale consisted of the following at December 31, 2017 and 2016 (in thousands):



	December 31, 2017
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Corporate bonds	$	38,383	$	—	$	(166	)	$	38,217
Agency securities	11,045		—		(42		)	11,003
Certificates of deposit	2,982		1		(2		)	2,981
Total available-for-sale investment securities	$	52,410	$	1	$	(210	)	$	52,201



	December 31, 2016
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Corporate bonds	$	30,492	$	9	$	(56	)	$	30,445
Agency securities	6,248		—		(20		)	6,228
Certificates of deposit	5,472		16		—			5,488
Total available-for-sale investment securities	$	42,212	$	25	$	(76	)	$	42,161

Available-for-sale Investments, by Remaining Contract Maturity



	December 31, 2017				December 31, 2016
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Due in 1 year or less	$	29,850	$	29,800	$	15,475	$	15,473
Due after 1 year through 3 years	22,560		22,401		26,737		26,688
Total available-for-sale investment securities	$	52,410	$	52,201	$	42,212	$	42,161

Schedule of Sales and Maturities

During the years ended December 31, 2017 and 2016, we had sales and maturities (which include calls) of investment securities, as follows (in thousands):



	Year Ended December 31, 2017
	Gross Realized Gains		Gross Realized Losses		Gross Proceeds from Sales		Gross Proceeds from Maturities
Corporate bonds	$	—	$	—	$	—	$	10,690
Agency securities	1		—		15		3,294
Certificates of deposit	—		—		—		2,490
	$	1	$	—	$	15	$	16,474



	Year Ended December 31, 2016
	Gross Realized Gains		Gross Realized Losses		Gross Proceeds from Sales		Gross Proceeds from Maturities
Corporate bonds	$	7	$	—	$	7,554	$	2,480
Agency securities	5		—		3,005		11,557
Certificates of deposit	—		—		—		1,245
Treasury bills	—		—		2,000		6,055
	$	12	$	—	$	12,559	$	21,337

Fair Value, Assets Measured on Recurring Basis



	December 31, 2017
	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	5,524	$	—	$	—	$	5,524
Available-for-sale investment securities:
Corporate bonds	—		38,217		—		38,217
Agency securities	—		11,003		—		11,003
Certificates of deposit	2,981		—		—		2,981
Total Assets	$	8,505	$	49,220	$	—	$	57,725



	December 31, 2016
	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	4,849	$	—	$	—	$	4,849
Available-for-sale investment securities:
Corporate bonds	—		30,445		—		30,445
Agency securities	—		6,228		—		6,228
Certificates of deposit	5,488		—		—		5,488
Total Assets	$	10,337	$	36,673	$	—	$	47,010

Fair Value, Liabilities Measured on Recurring Basis

The following tables summarize our financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2017 and 2016, by level within the fair value hierarchy (in thousands):



	December 31, 2017
	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	5,524	$	—	$	—	$	5,524
Available-for-sale investment securities:
Corporate bonds	—		38,217		—		38,217
Agency securities	—		11,003		—		11,003
Certificates of deposit	2,981		—		—		2,981
Total Assets	$	8,505	$	49,220	$	—	$	57,725



	December 31, 2016
	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	4,849	$	—	$	—	$	4,849
Available-for-sale investment securities:
Corporate bonds	—		30,445		—		30,445
Agency securities	—		6,228		—		6,228
Certificates of deposit	5,488		—		—		5,488
Total Assets	$	10,337	$	36,673	$	—	$	47,010

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property and Equipment

The estimated useful lives of our property and equipment are as follows:



Asset Type		Depreciation Period
Data center and computer equipment		3 years
Furniture and fixtures		7 years
Office equipment		2 to 5 years
Leasehold improvements		Shorter of remaining life of lease or asset life

Property and equipment consists of the following as of December 31, 2017 and 2016 (in thousands):



	December 31,
	2017			2016
Data center and computer equipment	$	5,233		$	4,913
Furniture and fixtures	2,415			2,465
Office equipment	763			726
Leasehold improvements	5,029			4,035
Gross property and equipment	13,440			12,139
Less: Accumulated depreciation	(6,744		)	(5,062		)
Total property and equipment, net	$	6,696		$	7,077

Internal-Use Software Development Costs (Tables)

12 Months Ended

Dec. 31, 2017

Research and Development [Abstract]

Schedule of Capitalized Computer Software

Internal-use software development costs were as follows (in thousands):



	December 31,
	2017			2016
Internal use software development costs, gross	$	44,626		$	33,545
Less: Accumulated amortization	(27,017		)	(18,006		)
Internal use software development costs, net	$	17,609		$	15,539

Scheduled of Future Amortization Expense

Future amortization expense with respect to capitalized software development costs as of December 31, 2017 is estimated as follows (in thousands):



Years Ending December 31,
2018	$	9,309
2019	6,061
2020	2,210
2021	29
Total amortization expense	$	17,609

Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Finite-Lived Intangible Assets

Intangible assets consisted of the following as of December 31, 2017 and 2016 (in thousands, except years):



	December 31, 2017
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Weighted Average Useful Life in Years
Customer relationships	$	790	$	(538	)	$	252	5.0
Technology	4,811		(3,871		)	940		6.0
Trademarks	930		(539		)	391		9.0
Partner relationships	680		(623		)	57		3.0
Non-compete agreements	40		(37		)	3		3.0
Domain names	273		(273		)	—		5.0
Patents	285		(203		)	82		5.0
	$	7,809	$	(6,084	)	$	1,725	5.9



	December 31, 2016
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Weighted Average Useful Life in Years
Customer relationships	$	790	$	(392	)	$	398	5.0
Technology	4,811		(3,070		)	1,741		6.0
Trademarks	930		(416		)	514		9.0
Partner relationships	680		(397		)	283		3.0
Non-compete agreements	40		(23		)	17		3.0
Domain names	273		(241		)	32		5.0
Patents	284		(164		)	120		5.0
	$	7,808	$	(4,703	)	$	3,105	5.9

Schedule of Finite-Lived Intangible Assets Amortization Expense

Amortization expense for each of the five fiscal years through December 31, 2022 is estimated as follows (in thousands):



Years Ending December 31,
2018	$	929
2019	352
2020	259
2021	124
2022	61
Total amortization expense	$	1,725

Commitment and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Payments for Operating Leases

A summary of our future minimum payments for obligations under non-cancellable operating leases is as follows (in thousands):



Years Ending December 31,
2018	$	2,446
2019	2,509
2020	2,512
2021	1,483
2022	179
Total lease commitments	$	9,129

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Stock Option Activity

A summary of our stock option activity for the year ended December 31, 2017 is as follows (number of shares in thousands):



	Number of Shares		Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Life in Years
Options outstanding as of December 31, 2016	1,718		$	8.75	8.2
Options granted	172		24.77
Options exercised	(165	)	4.02
Options cancelled/forfeited	(33	)	10.17
Options outstanding as of December 31, 2017	1,692		$	10.81	7.3

As of December 31, 2017:
Options vested or expected to vest	1,688		$	10.82	7.3
Options exercisable⁽¹⁾	830		$	7.22	6.4

Schedule of Valuation Assumptions, Stock Options

The following table summarizes information relating to our stock options granted during the years ended December 31, 2017, 2016 and 2015:



	Year Ended December 31,
	2017			2016			2015
Stock options granted (in thousands)	172			750			359
Weighted average exercise price per share	$	24.77		$	12.85		$	9.53
Weighted average grant-date fair value per share	$	9.58		$	4.85		$	6.89
Weighted average Black-Scholes model assumptions:
Risk-free interest rate	2.02		%	1.45		%	1.58		%
Expected term (in years)	6.4			5.9			6.2
Expected volatility	35		%	37		%	46		%
Expected dividend yield	—			—			—

Schedule of Restricted Stock Units Activity

A summary of activity in connection with our RSUs for the year ended December 31, 2017 is as follows (number of shares in thousands):



	Number of Shares		Weighted- Average Grant Date Fair Value per Share
Unvested as of December 31, 2016	496		$	13.34
Granted	315		26.10
Vested	(150	)	13.31
Forfeited	(63	)	16.59
Unvested as of December 31, 2017	598		$	19.75

Schedule of Restricted Stock Activity

A summary of activity in connection with our RSAs for the year ended December 31, 2017 is as follows (number of shares in thousands):



	Number of Shares		Weighted- Average Grant Date Fair Value per Share
Unvested as of December 31, 2016	46		$	8.55
Granted	9		33.30
Vested	(39	)	9.24
Forfeited	—		—
Unvested as of December 31, 2017	16		$	20.93

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation

Set forth below is a reconciliation of the components that caused our provision for income taxes to differ from amounts computed by applying the United States federal statutory rate of 34% for the years ended December 31, 2017, 2016 and 2015:



	Year Ended December 31,
	2017		2016		2015
Income tax benefit at the statutory rate	34	%	34	%	34	%
State and local income taxes, net of federal benefit	(14	)	7		3
Stock-based compensation expense	(15	)	(4	)	(2	)
Meals and entertainment	2		(2	)	(1	)
Permanent differences	—		(1	)	—
Change in valuation allowance	(60	)	(42	)	(38	)
Change in federal rate	74		—		—
Research and development tax credits	(20	)	7		3
Provision for income taxes	1	%	(1	)%	(1	)%

Schedule of Deferred Tax Assets and Liabilities

The components of deferred tax assets (liabilities) were as follows (in thousands):



	December 31,
	2017			2016
Deferred income tax assets:
Net operating loss carryforwards	$	19,519		$	31,436
Research and development tax credits	8,278			4,032
Other	2,493			2,771
Gross deferred tax assets	30,290			38,239
Valuation allowance	(23,827		)	(29,417		)
Deferred tax assets, net of valuation allowance	6,463			8,822
Deferred tax liabilities:
Property, equipment and software	(4,293		)	(5,820		)
Intangible assets	(6		)	(403		)
State taxes	(1,693		)	(2,040		)
Other	(549		)	(632		)
Total deferred tax liabilities	(6,541		)	(8,895		)
Total net deferred tax liabilities	$	(78	)	$	(73	)

Summary of Valuation Allowance

The change in the valuation allowance for the years ended December 31, 2017, 2016 and 2015 was as follows (in thousands):



	Year Ended December 31,
	2017			2016		2015
Valuation allowance, at beginning of year	$	29,417		$	25,926	$	19,900
Increase (decrease) in valuation allowance	(5,590		)	3,491		6,026
Valuation allowance, at end of year	$	23,827		$	29,417	$	25,926

Schedule of Unrecognized Tax Benefits Roll Forward

The following is a reconciliation of the total amounts of unrecognized tax benefits (in thousands):



	Year Ended December 31,
	2017			2016		2015
Unrecognized tax benefit beginning of year	$	4,032		$	2,867	$	2,014
Decreases-tax positions in prior year	(2,210		)	—		—
Increases-tax positions in current year	283			1,165		853
Unrecognized tax benefit end of year	$	2,105		$	4,032	$	2,867

Revenue and Other Information (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Schedule of Product Information by Revenue Categories

The following table presents our revenue categories for the years ended December 31, 2017, 2016 and 2015 (in thousands):



	Year Ended December 31,
	2017		2016		2015
Core solutions	$	57,132	$	43,775	$	32,119
Value+ services	80,847		56,965		37,998
Other	5,824		4,846		4,860
Total revenues	$	143,803	$	105,586	$	74,977

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) operating_segment reporting_unit	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Accounting Policies [Abstract]
Number of operating segments \| operating_segment	1
Number of reportable segments \| operating_segment	1
Restricted cash	$ 400,000	$ 400,000
Finite-Lived Intangible Assets [Line Items]
Goodwill	6,737,000	6,737,000
Impairment charges related to the identified long-lived assets	$ 0	0	$ 0
Number of reporting units \| reporting_unit	1
Advertising expense	$ 3,600,000	$ 3,600,000	$ 3,600,000
Expected dividend yield	0.00%
Capitalized Software Development Costs
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives	3 years

Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2017
Data center and computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	7 years
Office equipment \| Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	2 years
Office equipment \| Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	5 years

Summary of Significant Accounting Policies - Net Income (Loss) per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average common shares outstanding	33,876	33,639	21,486
Less: Weighted average unvested restricted shares subject to repurchase	27	78	150
Weighted average common shares outstanding; basic	33,849	33,561	21,336
Plus: Weighted average options, RSUs and restricted shares used to compute diluted net income per share	1,302	0	0
Weighted average common shares outstanding; diluted	35,151	33,561	21,336
Shares excluded from net loss per share attributable to common stockholders	27	2,294	1,357
Performance Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from net loss per share attributable to common stockholders	548
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from net loss per share attributable to common stockholders	0	1,718	1,171
Unvested RSAs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from net loss per share attributable to common stockholders	0	46	120
Unvested RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from net loss per share attributable to common stockholders	21	496	17
Contingent restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from net loss per share attributable to common stockholders	6	34	49

Summary of Significant Accounting Policies - Recent Accounting Pronouncements Not Yet Adopted (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit	$ (67,247)	$ (76,963)
Accounting Standards Update 2014-09 \| Pro Forma
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit	$ 3,000
Period of benefit	3 years

Investment Securities and Fair Value Measurements - Investment Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Amortized Cost	$ 52,410	$ 42,212
Gross Unrealized Gains	1	25
Gross Unrealized Losses	(210)	(76)
Estimated Fair Value	$ 52,201	$ 42,161
Maximum contractual maturity period	36 months	36 months
Amortized Cost
Due in 1 year or less	$ 29,850	$ 15,475
Due after 1 year through 3 years	22,560	26,737
Total available-for-sale investment securities	52,410	42,212
Estimated Fair Value
Due in 1 year or less	29,800	15,473
Due after 1 year through 3 years	22,401	26,688
Total available-for-sale investment securities	52,201	42,161
Corporate bonds
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Amortized Cost	38,383	30,492
Gross Unrealized Gains	0	9
Gross Unrealized Losses	(166)	(56)
Estimated Fair Value	38,217	30,445
Agency securities
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Amortized Cost	11,045	6,248
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(42)	(20)
Estimated Fair Value	11,003	6,228
Certificates of deposit
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Amortized Cost	2,982	5,472
Gross Unrealized Gains	1	16
Gross Unrealized Losses	(2)	0
Estimated Fair Value	$ 2,981	$ 5,488

Investment Securities and Fair Value Measurements - Sales and Maturities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Gross Realized Gains	$ 1	$ 12
Gross Realized Losses	0	0
Gross Proceeds from Sales	15	12,559	$ 4,100
Gross Proceeds from Maturities	16,474	21,337	26,136
Amortization and accretion of premium and discount	700	500	$ 200
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Gross Realized Gains	0	7
Gross Realized Losses	0	0
Gross Proceeds from Sales	0	7,554
Gross Proceeds from Maturities	10,690	2,480
Agency securities
Schedule of Available-for-sale Securities [Line Items]
Gross Realized Gains	1	5
Gross Realized Losses	0	0
Gross Proceeds from Sales	15	3,005
Gross Proceeds from Maturities	3,294	11,557
Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Gross Realized Gains	0	0
Gross Realized Losses	0	0
Gross Proceeds from Sales	0	0
Gross Proceeds from Maturities	$ 2,490	1,245
Treasury bills
Schedule of Available-for-sale Securities [Line Items]
Gross Realized Gains		0
Gross Realized Losses		0
Gross Proceeds from Sales		2,000
Gross Proceeds from Maturities		$ 6,055

Investment Securities and Fair Value Measurements - Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	$ 52,201	$ 42,161
Fair value, measurements, recurring
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total Assets	57,725	47,010
Fair value, measurements, recurring \| Level 1
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total Assets	8,505	10,337
Fair value, measurements, recurring \| Level 2
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total Assets	49,220	36,673
Fair value, measurements, recurring \| Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total Assets	0	0
Corporate bonds
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	38,217	30,445
Corporate bonds \| Fair value, measurements, recurring
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	38,217	30,445
Corporate bonds \| Fair value, measurements, recurring \| Level 1
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	0	0
Corporate bonds \| Fair value, measurements, recurring \| Level 2
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	38,217	30,445
Corporate bonds \| Fair value, measurements, recurring \| Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	0	0
Agency securities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	11,003	6,228
Agency securities \| Fair value, measurements, recurring
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	11,003	6,228
Agency securities \| Fair value, measurements, recurring \| Level 1
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	0	0
Agency securities \| Fair value, measurements, recurring \| Level 2
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	11,003	6,228
Agency securities \| Fair value, measurements, recurring \| Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	0	0
Certificates of deposit
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	2,981	5,488
Certificates of deposit \| Fair value, measurements, recurring
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	2,981	5,488
Certificates of deposit \| Fair value, measurements, recurring \| Level 1
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	2,981	5,488
Certificates of deposit \| Fair value, measurements, recurring \| Level 2
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	0	0
Certificates of deposit \| Fair value, measurements, recurring \| Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale investment securities	0	0
Money market funds \| Fair value, measurements, recurring
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Cash equivalents	5,524	4,849
Money market funds \| Fair value, measurements, recurring \| Level 1
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Cash equivalents	5,524	4,849
Money market funds \| Fair value, measurements, recurring \| Level 2
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Cash equivalents	0	0
Money market funds \| Fair value, measurements, recurring \| Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Cash equivalents	$ 0	$ 0

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Gross property and equipment	$ 13,440	$ 12,139
Less: Accumulated depreciation	(6,744)	(5,062)
Total property and equipment, net	6,696	7,077
Depreciation expense on property and equipment	2,300	2,300	$ 1,400
Data center and computer equipment
Property, Plant and Equipment [Line Items]
Gross property and equipment	5,233	4,913
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Gross property and equipment	2,415	2,465
Office equipment
Property, Plant and Equipment [Line Items]
Gross property and equipment	763	726
Leasehold improvements
Property, Plant and Equipment [Line Items]
Gross property and equipment	$ 5,029	$ 4,035

Internal-Use Software Development Costs - Software Development Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Research and Development [Abstract]
Internal use software development costs, gross	$ 44,626	$ 33,545
Less: Accumulated amortization	(27,017)	(18,006)
Internal use software development costs, net	17,609	15,539
Capitalized software development costs during the period	11,100	11,800	$ 8,000
Amortization expense with respect to software development costs during the period	$ 9,000	$ 6,200	$ 3,500

Internal-Use Software Development Costs - Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2018	$ 9,309
2019	6,061
2020	2,210
2021	29
Internal use software development costs, net	$ 17,609	$ 15,539

Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 7,809	$ 7,808
Accumulated Amortization	(6,084)	(4,703)
Net Carrying Value	$ 1,725	$ 3,105
Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life in Years	5 years 9 months 70 days	5 years 9 months 70 days
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 790	$ 790
Accumulated Amortization	(538)	(392)
Net Carrying Value	$ 252	$ 398
Customer relationships \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life in Years	5 years	5 years
Technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 4,811	$ 4,811
Accumulated Amortization	(3,871)	(3,070)
Net Carrying Value	$ 940	$ 1,741
Technology \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life in Years	6 years	6 years
Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 930	$ 930
Accumulated Amortization	(539)	(416)
Net Carrying Value	$ 391	$ 514
Trademarks \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life in Years	9 years	9 years
Partner relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 680	$ 680
Accumulated Amortization	(623)	(397)
Net Carrying Value	$ 57	$ 283
Partner relationships \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life in Years	3 years	3 years
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 40	$ 40
Accumulated Amortization	(37)	(23)
Net Carrying Value	$ 3	$ 17
Non-compete agreements \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life in Years	3 years	3 years
Domain names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 273	$ 273
Accumulated Amortization	(273)	(241)
Net Carrying Value	$ 0	$ 32
Domain names \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life in Years	5 years	5 years
Patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 285	$ 284
Accumulated Amortization	(203)	(164)
Net Carrying Value	$ 82	$ 120
Patents \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life in Years	5 years	5 years

Intangible Assets - Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 1,400	$ 1,400	$ 1,300
2018	929
2019	352
2020	259
2021	124
2022	61
Net Carrying Value	$ 1,725	$ 3,105

Long-term Debt (Details) - USD ($)		12 Months Ended
Long-term Debt (Details) - USD ($)	Oct. 09, 2015	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2015	Mar. 16, 2015
Debt Instrument [Line Items]
Interest expense		$ 800,000
Credit Facility
Debt Instrument [Line Items]
Line of credit, amount outstanding			$ 0	$ 0
Debt instrument, covenant, required minimum liquidity, amount	$ 12,500,000.0
Debt instrument, covenant, required maximum liquidity, amount	25,000,000.0
Credit Facility \| Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity						$ 10,000,000.0
Line of credit, amount outstanding					$ 10,000,000
Interest expense		400,000
Credit Facility \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	25,000,000.0					2,500,000.0
Potential increase to maximum borrowing capacity	10,000,000.0
Debt financing costs	$ 200,000					$ 100,000
Debt finance costs, net			$ 200,000	$ 200,000
Credit Facility \| New Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee per annum of the unused portion of the Revolving Facility above $10.0 million	0.25%
Revolving facility benchmark for commitment fees	$ 10,000,000.0
Commitment fee per annum of the unused portion of the Revolving Facility below $10.0 million	0.375%
Credit Facility \| New Revolving Credit Facility \| Federal Funds Rate
Debt Instrument [Line Items]
Variable rate, basis spread percent	0.50%
Credit Facility \| New Revolving Credit Facility \| One-Month LIBOR
Debt Instrument [Line Items]
Variable rate, basis spread percent	1.00%
Credit Facility \| New Revolving Credit Facility \| Prime Rate
Debt Instrument [Line Items]
Variable rate, basis spread percent	1.50%
Credit Facility \| New Revolving Credit Facility \| LIBOR
Debt Instrument [Line Items]
Variable rate, basis spread percent	2.50%
Wells Fargo \| Credit Facility \| Term Loan
Debt Instrument [Line Items]
Debt financing costs		300,000
Unidentified Third Party \| Credit Facility \| Term Loan
Debt Instrument [Line Items]
Debt financing costs		$ 100,000

Commitment and Contingencies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Operating lease obligations	$ 9,129,000
Rent expense	2,100,000	$ 2,000,000	$ 1,200,000
Per incident policy limit	$ 100,000
Quota share of tenant liability insurance provided, percent	100.00%
Other current liabilities
Loss Contingencies [Line Items]
Liability for reported claims and claims incurred but not reported	$ 500,000	300,000
Prepaid expenses and other current assets
Loss Contingencies [Line Items]
Deposits held with a third party related to insurance services collateral	$ 1,800,000	$ 1,200,000

Commitment and Contingencies - Future Minimum Operating Lease Payments (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2018	$ 2,446
2019	2,509
2020	2,512
2021	1,483
2022	179
Total lease commitments	$ 9,129

Stockholders' Equity - Amended and Restated Certificate of Incorporation (Details) - $ / shares	Dec. 31, 2017	Dec. 31, 2016	Jun. 25, 2015
Class of Stock [Line Items]
Capital stock, shares authorized			325,000,000
Preferred stock, shares authorized	25,000,000	25,000,000	25,000,000
Preferred stock, shares outstanding	0	0	0
Class A common stock
Class of Stock [Line Items]
Common stock, shares authorized	250,000,000	250,000,000	250,000,000
Common stock, par value (usd per share)	$ 0.0001	$ 0.0001	$ 0.0001
Class B common stock
Class of Stock [Line Items]
Common stock, shares authorized	50,000,000	50,000,000	50,000,000
Common stock, par value (usd per share)	$ 0.0001	$ 0.0001

Stockholders' Equity - Class A Common Stock and Class B Common Stock, Reverse Stock Split (Details)	12 Months Ended
	Dec. 31, 2017 vote
Class B common stock to Class A common stock
Class of Stock [Line Items]
Number of shares to be issued per share upon conversion	1
Number of shares to be issued per share upon automatic conversion	1
Automatic conversion threshold as a percent of Class B common stock	10.00%
Class A common stock
Class of Stock [Line Items]
Number of votes per share	1
Class B common stock
Class of Stock [Line Items]
Number of votes per share	10

Stockholders' Equity - Preferred Stock (Details) - shares	Dec. 31, 2017	Dec. 31, 2016	Jun. 25, 2015
Equity [Abstract]
Preferred stock, shares outstanding	0	0	0
Preferred stock, shares authorized	25,000,000	25,000,000	25,000,000

Stock-Based Compensation - Stock Option Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share options granted	172,000	750,000	359,000
Weighted average exercise price per share	$ 24.77	$ 12.85	$ 9.53
Options canceled/forfeited in shares	33,000
Remaining stock-based compensation expense for unvested options, not yet recognized	$ 1,800,000
Options exercised, intrinsic value	4,600,000	$ 1,900,000	$ 3,100,000
Options outstanding, intrinsic value	51,900,000
Options exercisable, intrinsic value	28,400,000
Options vested and expected to vest, intrinsic value	51,800,000
Employee service share-based compensation, tax benefit realized from exercise of stock options	5,200,000	200,000	0
Stock Options and PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2,900,000	$ 2,400,000	$ 700,000
Stock-based compensation expense, weighted average recognition period	1 year 2 months 12 days
2015 Stock Incentive Plan \| Class A common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of shares reserved for stock incentive plan	3,441,355		2,000,000
2015 Stock Incentive Plan \| Stock Options and PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term of stock options granted			10 years
2007 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized	677,417
2007 Stock Incentive Plan \| Stock Options and PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term of stock options granted	10 years
Vesting period	4 years
2019 Performance Metric \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share options granted	172,000
Weighted average exercise price per share	$ 24.77
2019 Performance Metric, Targeted Free Cash Flow Performance Metric \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share options granted	132,000
Percent of award target performance metric	100.00%
Vesting percent of awards granted	150.00%
2017 and 2018 Performance Metric \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share options granted	500,000
Percent of award target performance metric	150.00%
2016 Performance Metric \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of award target performance metric		150.00%
Stock-based compensation expense		$ 1,000,000
Share-based compensation options vested in shares	247,000
Percent of achievement of award target performance metric	148.00%
Options canceled/forfeited in shares		3,000
Share-Based Compensation Award, Tranche One \| 2019 Performance Metric, Targeted Free Cash Flow Performance Metric \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of award target performance metric	100.00%
Vesting percent of awards granted	61.00%
Share-Based Compensation Award, Tranche One \| 2017 and 2018 Performance Metric \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of award target performance metric	100.00%
Vesting percent of awards granted	67.00%
Share-Based Compensation Award, Tranche Two \| 2019 Performance Metric, Targeted Free Cash Flow Performance Metric \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of award target performance metric	80.00%
Vesting percent of awards granted	48.00%
Share-Based Compensation Award, Tranche Two \| 2017 and 2018 Performance Metric \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of award target performance metric	80.00%
Vesting percent of awards granted	53.00%
Share-Based Compensation Award, Tranche Three \| 2019 Performance Metric, Targeted Free Cash Flow Performance Metric \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of award target performance metric	80.00%
Shares vested	0
Stock-based compensation expense	$ 0
Share-Based Compensation Award, Tranche Three \| 2017 and 2018 Performance Metric \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of award target performance metric	80.00%
Shares vested	0
Stock-based compensation expense	$ 0
Share-Based Compensation Award, Tranche Four \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percent of awards granted	110.00%
Share-Based Compensation Award, Tranche Four \| 2019 Performance Metric \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share options granted	40,000
Percent of award target performance metric	50.00%
Vesting percent of awards granted	50.00%
Share-Based Compensation Award, Tranche Four \| 2017 and 2018 Performance Metric \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of award target performance metric	50.00%
Share-Based Compensation Award, Tranche Five \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percent of awards granted	115.00%
Share-Based Compensation Award, Tranche Six \| 2019 Performance Metric \| PSOs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percent of awards granted	110.00%
Shares vested	0
Stock-based compensation expense	$ 0
Beneficial Owner \| 2007 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value assumptions, exercise price threshold as a percent of common stock at grant date	110.00%

Stock-Based Compensation - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Shares
Options outstanding, beginning balance (shares)	1,718,000
Stock options granted (in thousands)	172,000	750,000	359,000
Options exercised (shares)	(165,000)
Options canceled/forfeited (shares)	(33,000)
Options outstanding, ending balance (shares)	1,692,000	1,718,000
Options vested of expected to vest (shares)	1,688,000
Options exercisable (shares)	830,000
Weighted Average Exercise Price per Share
Options outstanding, beginning balance (usd per share)	$ 8.75
Options granted (usd per share)	24.77	$ 12.85	$ 9.53
Options exercised (usd per share)	4.02
Options canceled/forfeited (usd per share)	10.17
Options outstanding, ending balance (usd per share)	10.81	$ 8.75
Options vested and expected to vest, weighted average exercise price (usd per share)	10.82
Options exercisable, weighted average exercise price (usd per share)	$ 7.22
Options outstanding, weighted average remaining contractual life	7 years 3 months 18 days	8 years 2 months 12 days
Options vested or expected to vest, weighted average remaining contractual life	7 years 3 months 18 days
Options exercisable, weighted average remaining contractual life	6 years 4 months 24 days
Early exercisable stock option
Number of Shares
Options exercisable (shares)	65,000
Weighted Average Exercise Price per Share
Options exercisable, weighted average exercise price (usd per share)	$ 5.64
Options exercisable, weighted average remaining contractual life	7 years 1 month 6 days

Stock-Based Compensation - Valuation Assumptions (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (in thousands)	172	750	359
Weighted average exercise price per share	$ 24.77	$ 12.85	$ 9.53
Weighted average grant-date fair value per share	$ 9.58	$ 4.85	$ 6.89
Stock Options and PSOs
Weighted average Black-Scholes model assumptions:
Risk-free interest rate	2.02%	1.45%	1.58%
Expected term (in years)	6 years 4 months 24 days	5 years 10 months 24 days	6 years 2 months 12 days
Expected volatility	35.00%	37.00%	46.00%
Expected dividend yield	0.00%	0.00%	0.00%

Stock-Based Compensation - Restricted Stock Units (Details) - RSUs and PSUs	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Number of Shares
Unvested, beginning balance (shares) \| shares	496,000
Granted (shares) \| shares	315,000
Vested (shares) \| shares	(150,000)
Forfeited (shares) \| shares	(63,000)
Unvested, ending balance (shares) \| shares	598,000
Weighted- Average Grant Date Fair Value per Share
Unvested, beginning balance (usd per share) \| $ / shares	$ 13.34
Granted (usd per share) \| $ / shares	26.10
Vested (usd per share) \| $ / shares	13.31
Forfeited (usd per share) \| $ / shares	16.59
Unvested, ending balance (usd per share) \| $ / shares	$ 19.75

Stock-Based Compensation - Restricted Stock Units Narrative (Details) - USD ($)	1 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
RSUs and PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (shares)		315,000
Shares vested		150,000
Stock-based compensation expense		$ 3,600,000	$ 1,800,000	$ 100,000
Remaining stock-based compensation expense for unvested shares, not yet recognized		$ 8,300,000
Stock-based compensation expense, weighted average recognition period		2 years 4 months 24 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (shares)		202,000
Vesting period	4 years	4 years
PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (shares)		100,000	56,000
Percent of award target performance metric		100.00%	100.00%
Shares vested		41,000
Percent of achievement of award target performance metric		148.00%
Stock-based compensation expense			$ 500,000
PSUs \| Share-Based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of award target performance metric		150.00%	150.00%
Vesting percent of awards granted			150.00%
PSUs \| Share-Based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of award target performance metric		80.00%
Shares vested		0
Stock-based compensation expense		$ 0
PSUs \| Share-Based Compensation Award, Tranche Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of award target performance metric			80.00%
PSUs \| Share-Based Compensation Award, Tranche Four
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of award target performance metric			50.00%
Shares vested			0
Stock-based compensation expense			$ 0
PSUs \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of award target performance metric		0.00%	0.00%
PSUs \| Minimum \| Share-Based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percent of awards granted		150.00%
PSUs \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of award target performance metric		165.00%	150.00%
PSUs \| Maximum \| Share-Based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percent of awards granted		165.00%
2016 Performance Metric \| PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (shares)		13,000

Stock-Based Compensation - Restricted Stock Awards (Details) - RSAs - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Shares
Unvested, beginning balance (shares)	46
Granted (shares)	9
Vested (shares)	(39)
Forfeited (shares)	0
Unvested, ending balance (shares)	16	46
Weighted- Average Grant Date Fair Value per Share
Unvested, beginning balance (usd per share)	$ 8.55
Granted (usd per share)	33.30
Vested (usd per share)	9.24
Forfeited (usd per share)	0.00
Unvested, ending balance (usd per share)	$ 20.93	$ 8.55
Stock-based compensation expense	$ 358	$ 454	$ 381
Fair value of shares vested	354
Remaining stock-based compensation expense for unvested shares, not yet recognized	$ 200
Stock-based compensation expense, weighted average recognition period	7 months 10 days
Employee
Weighted- Average Grant Date Fair Value per Share
Vesting period	4 years
Non-Employee Director
Weighted- Average Grant Date Fair Value per Share
Vesting period	1 year

Income Taxes - Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income tax expense	$ 58	$ 67	$ 75
Income tax benefit at the statutory rate	34.00%	34.00%	34.00%
State and local income taxes, net of federal benefit	(14.00%)	7.00%	3.00%
Stock-based compensation expense	(15.00%)	(4.00%)	(2.00%)
Meals and entertainment	2.00%	(2.00%)	(1.00%)
Permanent differences	0.00%	(1.00%)	0.00%
Change in valuation allowance	(60.00%)	(42.00%)	(38.00%)
Change in federal rate	74.00%	0.00%	0.00%
Research and development tax credits	(20.00%)	7.00%	3.00%
Provision for income taxes	1.00%	(1.00%)	(1.00%)

Income Taxes - Components of Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred income tax assets:
Net operating loss carryforwards	$ 19,519	$ 31,436
Research and development tax credits	8,278	4,032
Other	2,493	2,771
Gross deferred tax assets	30,290	38,239
Valuation allowance	(23,827)	(29,417)	$ (25,926)	$ (19,900)
Deferred tax assets, net of valuation allowance	6,463	8,822
Deferred tax liabilities:
Property, equipment and software	(4,293)	(5,820)
Intangible assets	(6)	(403)
State taxes	(1,693)	(2,040)
Other	(549)	(632)
Total deferred tax liabilities	(6,541)	(8,895)
Total net deferred tax liabilities	(78)	$ (73)
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	73,500
Federal \| Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Credit carryforwards	5,000
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	48,000
State \| Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Credit carryforwards	$ 5,400

Income Taxes - Changes in Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes In Valuation Allowance [Roll Forward]
Valuation allowance, at beginning of year	$ 29,417	$ 25,926	$ 19,900
Increase (decrease) in valuation allowance	(5,590)	3,491	6,026
Valuation allowance, at end of year	$ 23,827	$ 29,417	$ 25,926

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefit beginning of year	$ 4,032,000	$ 2,867,000	$ 2,014,000
Decreases-tax positions in prior year	(2,210,000)	0	0
Increases-tax positions in current year	283,000	1,165,000	853,000
Unrecognized tax benefit end of year	2,105,000	4,032,000	$ 2,867,000
Income tax examination, penalties and interest accrued	0	$ 0
Reduction in net deferred tax assets	$ 7,200,000

Revenue and Other Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Product Information [Line Items]
Revenue	$ 143,803	$ 105,586	$ 74,977
Core solutions
Product Information [Line Items]
Revenue	57,132	43,775	32,119
Value plus services
Product Information [Line Items]
Revenue	80,847	56,965	37,998
Other
Product Information [Line Items]
Revenue	$ 5,824	$ 4,846	$ 4,860

Retirement Plans (Details) - USD ($)	12 Months Ended
Retirement Plans (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Benefits [Abstract]
Defined contribution plan, employer discretionary contribution amount	$ 800,000	$ 1,100,000	$ 0
Defined contribution plan, cost recognized	$ 800,000	$ 700,000	$ 400,000