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Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2018	Oct. 22, 2018
Document Information [Line Items]
Entity Registrant Name	APPFOLIO INC
Entity Central Index Key	0001433195
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity emerging growth company	true
Entity small business	false
Entity emerging growth transition period	true
Class A common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		16,110,969
Class B common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		18,139,559

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 13,745	$ 16,109
Investment securities—current	31,823	29,800
Accounts receivable, net	5,489	3,387
Prepaid expenses and other current assets	10,916	4,546
Total current assets	61,973	53,842
Investment securities—noncurrent	19,861	22,401
Property and equipment, net	6,699	6,696
Capitalized software, net	19,172	17,609
Goodwill	15,548	6,737
Intangible assets, net	6,179	1,725
Other assets	6,757	1,238
Total assets	136,189	110,248
Current liabilities
Accounts payable	1,108	610
Accrued employee expenses	7,493	10,710
Accrued expenses	7,715	4,289
Deferred revenue	3,172	7,080
Other current liabilities	1,296	1,223
Total current liabilities	20,784	23,912
Other liabilities	7,042	1,257
Total liabilities	27,826	25,169
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock, $0.0001 par value, 25,000 authorized and no shares issued and outstanding as of September 30, 2018 and December 31, 2017	0	0
Additional paid-in capital	155,556	152,531
Accumulated other comprehensive loss	(232)	(209)
Accumulated deficit	(46,965)	(67,247)
Total stockholders’ equity	108,363	85,079
Total liabilities and stockholders’ equity	136,189	110,248
Class A common stock
Stockholders’ equity:
Common stock	2	1
Class B common stock
Stockholders’ equity:
Common stock	$ 2	$ 3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
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	15,984,000	14,879,000
Common stock, shares outstanding	15,984,000	14,879,000
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	18,250,000	19,102,000
Common stock, shares outstanding	18,250,000	19,102,000

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenue	$ 50,126	$ 37,903	$ 139,706	$ 105,906
Costs and operating expenses:
Cost of revenue (exclusive of depreciation and amortization)	19,282	14,053	53,624	40,747
Sales and marketing	8,681	7,257	23,711	21,556
Research and product development	6,440	4,367	17,523	11,998
General and administrative	6,541	5,405	17,105	15,310
Depreciation and amortization	3,705	3,237	10,784	9,347
Total costs and operating expenses	44,649	34,319	122,747	98,958
Income from operations	5,477	3,584	16,959	6,948
Other income (expense), net	1	(5)	(20)	(93)
Interest income, net	229	155	631	377
Income before provision for income taxes	5,707	3,734	17,570	7,232
Provision for income taxes	183	52	252	93
Net income	$ 5,524	$ 3,682	$ 17,318	$ 7,139
Net income per common share:
Basic (usd per share)	$ 0.16	$ 0.11	$ 0.51	$ 0.21
Diluted (usd per share)	$ 0.16	$ 0.10	$ 0.49	$ 0.20
Weighted average common shares outstanding:
Basic (in shares)	34,219	33,905	34,154	33,817
Diluted (in shares)	35,610	35,205	35,524	35,091

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 5,524	$ 3,682	$ 17,318	$ 7,139
Other comprehensive income (loss):
Changes in unrealized gains (losses) on investment securities	57	26	(23)	28
Comprehensive income	$ 5,581	$ 3,708	$ 17,295	$ 7,167

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Condensed Consolidated Statement of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock Class A common stock	Common Stock Class B common stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment resulting from adoption of ASU 2014-09 (Note 2)	$ 2,964					$ 2,964
Beginning balance (in shares) at Dec. 31, 2017		14,879	19,102
Beginning balance at Dec. 31, 2017	$ 85,079	$ 1	$ 3	$ 152,531	$ (209)	(67,247)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (shares)	143	143
Exercise of stock options	$ 713			713
Stock-based compensation	4,992			4,992
Vesting of restricted stock units, net of shares withheld for taxes (in shares)		105
Vesting of restricted stock units, net of shares withheld for taxes	(2,706)			(2,706)
Vesting of early exercised shares	26			26
Conversion of Class B stock to Class A stock (in shares)		852	(852)
Conversion of Class B stock to Class A stock	0	$ 1	$ (1)
Issuance of restricted stock awards (in shares)		5
Issuance of restricted stock awards	0	$ 0
Other comprehensive loss	(23)				(23)
Net income	17,318					17,318
Ending balance (in shares) at Sep. 30, 2018		15,984	18,250
Ending balance at Sep. 30, 2018	$ 108,363	$ 2	$ 2	$ 155,556	$ (232)	$ (46,965)

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash from operating activities
Net income	$ 17,318	$ 7,139
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	10,784	9,347
Purchased investment premium, net of amortization	99	(22)
Amortization of deferred financing costs	48	48
Amortization of Other Deferred Charges	1,312	0
Loss on disposal of property and equipment	18	94
Stock-based compensation	4,419	4,304
Changes in operating assets and liabilities:
Accounts receivable	(1,465)	(908)
Prepaid expenses and other current assets	(5,214)	(856)
Other assets	(5,003)	(54)
Accounts payable	477	369
Accrued employee expenses	(3,225)	846
Accrued expenses	3,397	1,713
Deferred revenue	(4,247)	(130)
Other liabilities	5,883	(334)
Net cash provided by operating activities	24,601	21,556
Cash from investing activities
Purchases of property and equipment	(1,740)	(1,680)
Additions to capitalized software	(8,997)	(8,085)
Purchases of investment securities	(28,784)	(17,597)
Sales of investment securities	701	15
Maturities of investment securities	28,477	10,974
Cash paid in business acquisition	(14,441)	0
Purchases of intangible assets	0	(1)
Net cash used in investing activities	(24,784)	(16,374)
Cash from financing activities
Proceeds from stock option exercises	713	508
Tax withholding for net share settlement	(2,894)	(1,608)
Proceeds from issuance of debt	93	88
Principal payments on debt	(93)	(88)
Net cash used in financing activities	(2,181)	(1,100)
Net (decrease) increase in cash, cash equivalents and restricted cash	(2,364)	4,082
Cash, cash equivalents and restricted cash
Beginning of period	16,537	11,126
End of period	14,173	15,208
Noncash investing and financing activities
Purchases of property and equipment included in accounts payable and accrued expenses	55	271
Additions of capitalized software included in accrued employee expenses	298	231
Stock-based compensation capitalized for software development	$ 751	$ 548

Condensed Consolidated Statements of Cash Flows - Cash Reconciliation - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017
Statement of Cash Flows [Abstract]
Cash and cash equivalents	$ 13,745	$ 14,781
Restricted cash included in other assets	428	427
Total cash, cash equivalents and restricted cash	$ 14,173	$ 15,208

Nature of Business	9 Months Ended
Nature of Business	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Nature of Business AppFolio, Inc. (“we,” "us" or "our") 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. Our mission is to revolutionize vertical industry businesses by providing great software and services. We believe we accomplish this mission by delivering software solutions and services that provide our customers with 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. Our property manager customers directly and indirectly account for more than 90% of our annual revenue and include third-party property managers and owner operators who manage single- and multi-family residences, commercial properties, community associations and student housing, as well as mixed real estate portfolios. Our legal customers are typically small law firms that directly and indirectly account for less than 10% of our annual revenue. Recent Developments Acquisition of WegoWise, Inc. On August 31, 2018, we completed the acquisition of substantially all of the assets of WegoWise, Inc. ("WegoWise"), a provider of cloud-based utility analytics software solutions serving the real estate market. The WegoWise platform empowers building owners and third-party property managers to better manage operating and capital expenditures relating to utilities, and we expect that the acquisition will provide enhanced functionality to our real estate customers over time. For additional information regarding this acquisition, refer to Note 3, Acquisition of WegoWise.

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Presentation and Significant Accounting Policies

The accompanying unaudited Condensed Consolidated Financial Statements were prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information. Certain information and disclosures normally included in consolidated financial statements prepared in accordance with GAAP have been condensed or omitted. Accordingly, these Condensed Consolidated Financial Statements should be read in conjunction with our audited consolidated financial statements and the related notes included in our Annual Report filed with the Securities and Exchange Commission ("SEC") on February 26, 2018. The year-end condensed balance sheet was derived from our audited consolidated financial statements. Our unaudited interim Condensed Consolidated Financial Statements include, in the opinion of management, all adjustments, consisting of normal and recurring items, necessary for the fair statement of the Condensed Consolidated Financial Statements. The operating results for the nine months ended September 30, 2018 are not necessarily indicative of the results expected for the full year ending December 31, 2018.

Changes in Accounting Policies

On January 1, 2018, we adopted Financial Accounting Standards Board ("FASB") Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers (as amended, "ASU 2014-09"), and have revised certain related accounting policies in connection with revenue recognition and deferred costs, as follows:

Revenue Recognition

We generate revenue from our customers primarily for subscriptions to access our core solutions and Value+ services for our cloud-based property management and legal software solutions. Revenue is recognized upon transfer of control of promised services in an amount that reflects the consideration we expect to receive in exchange for those services. We enter into contracts that can include various combinations of services, which are generally capable of being distinct, distinct within the context of the contract, and accounted for as separate performance obligations. Revenue is recognized net of any taxes collected from customers, which are subsequently remitted to governmental authorities. We have applied the practical expedient to recognize revenue in proportion to the amount we have the right to invoice for certain core solutions and Value+ services revenue as that amount corresponds directly with our performance completed to date. Refer to Note 10, Revenue and Other Information for the disaggregated breakdown of revenues between core solutions, Value+ services and other revenues.

Core Solutions

We charge our customers on a subscription basis for our core solutions. Our subscription fees are designed to scale to the size of our customers' businesses. 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. Our customers do not have rights to the underlying software code of our solutions, and, accordingly, we recognize subscription revenue over time on a straight-line basis over the contract term beginning on the date that our service is made available to the customer. The term of our core solutions subscription agreements generally ranges from one month to one year. We typically invoice our customers for subscription services in monthly or annual installments, in advance of the subscription period.

Value+ Services

We charge our customers for Value+ services based on subscriptions or usage-based fees. Subscription Value+ services include website hosting and contact center services. Usage-based Value+ services include fees for services such as electronic payment processing, applicant screening, legal liability to landlord insurance, renters insurance, collections, and online vacancy advertising services. 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.

We work with third party partners to provide certain of our Value+ services. For these Value+ services, we evaluate whether we are the principal, and report revenues on a gross basis, or the agent, and report revenues on a net basis. In this assessment we consider if we obtain control of the specified services before they are transferred to the customer, as well as other indicators such as whether we are the party primarily responsible for fulfillment, and whether we have discretion in establishing price.

Other Revenues

Other revenues include one-time services related to implementation and data migration of our core solutions, website design services, online vacancy advertising services offered to legacy RentLinx customers, and revenues from subscriptions to our utility tracking software and compliance reporting services, as well as one-time implementation fees for legacy WegoWise customers. The fees for implementation and data migration services are billed upon signing our core subscription contract and are not recognized until the core solution is accessible and fully functional for our customer's use. Our website design services are billed when the website design is completed and delivered to the customer. The online vacancy advertising services revenue includes a combination of monthly subscription revenue, which is billed in advance and deferred over the subscription period, and verified leads and clicks for online rental vacancies, which are billed when the services have been rendered and are recognized upon completion of the services. Revenue from subscriptions to our utility tracking software and compliance reporting services are billed in advance and deferred over the subscription period.

Contracts with Multiple Performance Obligations

Many of our contracts with customers contain multiple performance obligations. For these contracts, the performance obligations include access and use of our core solutions, implementation services, and customer support. We account for individual performance obligations separately if they are distinct. Determining whether products and services are considered distinct performance obligations that should be accounted for separately versus together may require significant judgment.

The transaction price is allocated to each performance obligation on a relative standalone selling price basis. Judgment is required to determine the standalone selling price for each distinct performance obligation. We typically have more than one standalone selling price for individual products and services due to the stratification of those products and services by customers and circumstances. In these instances, we determine the standalone selling price based on our overall pricing objectives, taking into consideration customer demographics and other factors. Fees are fixed based on rates specified in the subscription agreements, which do not provide for any refunds or adjustments. In determining the transaction price, we have applied the practical expedient which allows us not to adjust the consideration for the effects of the time value of money as the time between when we transfer the promised service to a customer and when a customer pays is one year or less. We do not disclose the value of unsatisfied performance obligations for contracts with an original expected term of one year or less.

Deferred Revenues

We record deferred revenues when cash payments are received in advance of our performance. During the nine months ended September 30, 2018 we recognized $6.7 million of revenues that were included in the deferred revenue balance at the beginning of the period.

Deferred Costs

Deferred costs, which primarily consist of sales commissions, are considered incremental and recoverable costs of obtaining a contract with a customer. These costs are deferred and then amortized on a straight-line basis over a period of benefit that we have determined to be three years. We typically do not pay commissions for contract renewals. We determined the period of benefit by taking into consideration our customer contract term, the useful life of our internal-use software, average customer life, and other factors. Amortization expense for the deferred costs is included within cost of revenue and sales and marketing expense in the accompanying Condensed Consolidated Statements of Operations.

Deferred costs were $5.8 million as of September 30, 2018, of which $2.5 million is included in prepaid expenses and other current assets and $3.3 million is included in other assets in the accompanying Condensed Consolidated Balance Sheets. Amortization expense for deferred costs was $0.5 million and $1.3 million for the three and nine months ended September 30, 2018, respectively. For the nine months ended September 30, 2018, no impairments were identified in relation to the costs capitalized for the 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, 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.

Net Income per Common Share

The net income per common share was the same for shares of our Class A and Class B common stock 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 shares of our Class A and Class B common stock used to compute net income per common share (in thousands):



	Three Months Ended September 30,		Nine Months Ended September 30,
	2018	2017	2018	2017
Weighted average common shares outstanding	34,227	33,923	34,166	33,848
Less: Weighted average unvested restricted shares subject to repurchase	8	18	12	31
Weighted average common shares outstanding; basic	34,219	33,905	34,154	33,817
Plus: Weighted average options, restricted stock units and restricted shares used to compute diluted net income per common share	1,391	1,300	1,370	1,274
Weighted average common shares outstanding; diluted	35,610	35,205	35,524	35,091

For the three and nine month periods ended September 30, 2018 and 2017, an aggregate of approximately 503,000 and 571,000 shares, respectively, underlying performance based options ("PSOs") and performance based restricted stock units ("PSUs"), are not included in the computations of diluted and anti-dilutive shares as they are considered contingently issuable upon the satisfaction of pre-defined performance measures and their respective performance measures have not been met.

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 per common share for the three and nine months ended September 30, 2018 and 2017 (in thousands):



	Three Months Ended September 30,		Nine Months Ended September 30,
	2018	2017	2018	2017
Unvested restricted stock units	3	13	3	13
Contingent restricted stock units⁽¹⁾	1	6	1	6
Total shares excluded from diluted net income per common share	4	19	4	19

⁽¹⁾ The reported shares are based on fixed price restricted stock unit (“RSU”) commitments for which the number of shares was not determined at the grant date. For the purposes of this table, the number of shares has 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

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

In May 2014, the FASB issued ASU 2014-09, 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.

We adopted 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. We recognized the cumulative effect of initially applying the New Revenue Standard as an adjustment to the opening balance of retained earnings. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. We updated our accounting policies, processes, internal controls and information systems to conform to the New Revenue Standard's reporting and disclosure requirements.

The adoption of the New Revenue Standard did not have an impact on our revenues. The most significant impact relates to the deferral of incremental costs of obtaining contracts. Prior to the adoption of the New Revenue Standard, our commissions were expensed as incurred.

The cumulative effects of the changes made to our Condensed Consolidated Balance Sheet at January 1, 2018 for the adoption of the New Revenue Standard were as follows (in thousands):



	Balance at December 31, 2017			Adjustments		Balance at January 1, 2018
Assets
Prepaid expenses and other current assets	$	4,546		$	1,148	$	5,694
Other assets	1,238			1,816		3,054

Equity
Accumulated deficit	$	(67,247	)	$	2,964	$	(64,283	)

The following tables summarize the current period impacts of adopting the New Revenue Standard on our Condensed Consolidated Financial Statements (in thousands):

Condensed Consolidated Balance Sheet:



	September 30, 2018
	As Reported			Balances Without Adoption of ASU 2014-09			Effect of Adoption
Assets
Prepaid expenses and other current assets	$	10,916		$	8,381		$	2,535
Other assets	6,757			3,486			3,271

Equity
Accumulated deficit	$	(46,965	)	$	(52,772	)	$	5,807

Condensed Consolidated Statements of Operations:



	Three Months Ended September 30, 2018							Nine Months Ended September 30, 2018
	As Reported		Balances Without Adoption of ASU 2014-09		Effect of Adoption			As Reported		Balances Without Adoption of ASU 2014-09		Effect of Adoption
Costs and operating expenses:
Cost of revenue (exclusive of depreciation and amortization)	$	19,282	$	19,342	$	(60	)	$	53,624	$	53,806	$	(182	)
Sales and marketing	8,681		9,540		(859		)	23,711		26,371		(2,660		)
Total costs and operating expenses	44,649		45,568		(919		)	122,747		125,589		(2,842		)
Income from operations	5,477		4,558		919			16,959		14,117		2,842
Income before provision for income taxes	5,707		4,788		919			17,570		14,728		2,842
Net income	$	5,524	$	4,605	$	919		$	17,318	$	14,476	$	2,842

Net income per common share:
Basic	$	0.16	$	0.13	$	0.03		$	0.51	$	0.42	$	0.09
Diluted	$	0.16	$	0.13	$	0.03		$	0.49	$	0.41	$	0.08

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. We adopted ASU 2016-15 effective January 1, 2018. The adoption of this guidance did not have a material impact on our statements 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. We adopted ASU 2016-16 effective January 1, 2018. The adoption of this guidance did not have a material impact on our financial condition, results of operations, cash flows or disclosures.

In November 2016, the FASB issued ASU No. 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. We adopted ASU 2016-18 effective January 1, 2018. The adoption of this guidance changed the presentation of restricted cash on our statements 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 early adopted ASU 2017-04 effective January 1, 2018. The adoption of this guidance did not have a material impact on our financial condition, results of operations, cash flows or disclosures.

In May 2017, the FASB issued ASU No. 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. We adopted ASU 2017-09 effective January 1, 2018. The adoption of this guidance did not have a material impact on our financial condition, results of operations, cash flows or disclosures.

Recent Accounting Pronouncements Not Yet Adopted

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. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements ("ASU 2018-11"). Among other things, ASU 2018-11 provides administrative relief by allowing entities to implement the lease standard on a modified retrospective basis, similar to the method that we used to adopt the new revenue standard. Effectively, the modified retrospective basis permits us to adopt the lease standard through a cumulative effect adjustment to our opening balance sheet for the first quarter of fiscal year 2019, with the cumulative effect accounted for as a component of retained earnings, and report under the new lease standard on a post adoption basis. We are currently evaluating the impact these standards will have on our results of operations and cash flows, and we anticipate a material increase in assets and liabilities due to the recording of the required right-of-use asset and corresponding liability for all lease obligations that are currently classified as operating leases.

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 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 annual periods, and interim periods within those annual periods, 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 consistent with ASU 2017-08.

In June 2018, the FASB issued ASU No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting ("ASU 2018-07"). This amendment expands the scope of Topic 718, Compensation—Stock Compensation (which currently only includes share-based payments to employees) to include share-based payments issued to nonemployees for goods or services. Consequently, the accounting for share-based payments to nonemployees and employees will be substantially aligned. ASU 2018-07 supersedes Subtopic 505-50, Equity—Equity-Based Payments to Non-Employees and is effective for annual reporting periods, and interim periods within those annual periods, beginning 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 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, a series of amendments which align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected by these amendments. For public business entities, the amendments are effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2019. 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.

Acquisition of WegoWise

9 Months Ended

Sep. 30, 2018

Business Combinations [Abstract]

Acquisition of WegoWise

On August 31, 2018, we completed the acquisition of substantially all of the assets of WegoWise, a provider of cloud-based utility analytics software solutions serving the real estate market. The WegoWise platform empowers building owners and third-party property managers to better manage operating and capital expenditures relating to utilities, and we expect that the acquisition will provide enhanced functionality to our real estate customers over time.

The consideration paid in cash for the assets was $14.4 million, of which $2.0 million will be held in escrow for twelve months to satisfy WegoWise’s indemnity obligations. In addition, if during the period beginning immediately after the closing of the transaction (the "Closing") and ending on the six month anniversary of the Closing, we enter into contracts with certain third parties (each, a "Milestone Contract"), we will be obligated to pay to WegoWise the aggregate amount of the recurring revenues billed and collected from the Milestone Contract that results in the highest amount of recurring revenues billed during the twelve month period ("Determination Period") following the date recurring revenue is first billed for such Milestone Contract, but in no event will the Determination Period extend beyond the date which is the 15th month anniversary of the execution of the Milestone Contract (and we will not be obligated to pay WegoWise for any recurring revenues resulting from any other Milestone Contracts). We have determined that the fair value of the contingent consideration is de minimis based on facts and circumstances that existed on the Closing. The significant inputs used in the fair value measurement of the contingent consideration were the probability of entering into the Milestone Contracts during the Determination Period and the potential payment amounts for each Milestone Contract. The fair value of the contingent consideration may change over time as we continue to evaluate the likelihood of payment. Changes in the fair value of the contingent consideration would be recognized as an expense within the Condensed Consolidated Statements of Operations.

The transaction was accounted for using the acquisition method, and as a result, assets acquired and liabilities assumed were recorded at their estimated fair values as of the acquisition date. The preliminary fair values were based on management’s analysis as well as work performed by third‑party valuation specialists. We are in the process of finalizing the valuation of the assets. The following table summarizes the purchase price allocation (in thousands) as well as the estimated useful lives of the acquired intangible assets over which they are amortized on a straight-line basis, as this approximates the pattern in which economic benefits are consumed:



	Amount		Estimated Useful Life (in years)
Net assets	$	270
Identified intangible assets:
Customer relationships	1,170		5.0
Technology and database	3,620		10.0
Trademark and trade name	370		10.0
Non-compete agreement	60		5.0
Backlog	140		1.0
Total intangible assets subject to amortization	5,360		8.6
Goodwill	8,811		Indefinite
Purchase consideration, paid in cash	$	14,441

Goodwill is mainly attributable to synergies expected from the acquisition and assembled workforce and is deductible for U.S. federal income tax purposes.

We incurred a total of $210,000 in transaction costs related to the acquisition and expensed all transaction costs incurred during the period in which such service was received. The results of operations of WegoWise since the acquisition are included in our Condensed Consolidated Statements of Operations for the three and nine months ended September 30, 2018. Revenue and net income (loss) attributable to WegoWise, in the period from the acquisition date of August 31, 2018 through September 30, 2018, were $79,000 and $(329,000), respectively.

The following unaudited pro forma information has been prepared for illustrative purposes only, and assumes that the acquisition occurred on January 1, 2017 and includes pro forma adjustments related to the amortization of acquired intangible assets, elimination of historical interest expense on WegoWise debt, which was paid off as part of the transaction, and the transaction costs incurred. The unaudited pro forma results have been prepared based on estimates and assumptions, which we believe are reasonable; however, they are not necessarily indicative of the consolidated results of operations had the acquisition occurred on January 1, 2017, or of future results of operations. The unaudited pro forma results are as follows (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Revenue	$	50,850	$	38,653	$	142,158	$	108,172
Net income	$	5,484	$	2,423	$	15,444	$	3,493

Net income per common share:
Basic	$	0.16	$	0.07	$	0.45	$	0.10
Diluted	$	0.15	$	0.07	$	0.43	$	0.10

Investment Securities and Fair Value Measurements

9 Months Ended

Sep. 30, 2018

Fair Value Disclosures [Abstract]

Investment Securities and Fair Value Measurements

Investment Securities

Investment securities classified as available-for-sale consisted of the following at September 30, 2018 and December 31, 2017 (in thousands):



	September 30, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Corporate bonds	$	33,239	$	1	$	(180	)	$	33,060
Agency securities	10,283		—		(45		)	10,238
Certificates of deposit	492		—		(1		)	491
Treasury securities	7,902		—		(7		)	7,895
Total available-for-sale investment securities	$	51,916	$	1	$	(233	)	$	51,684



	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

As of September 30, 2018, 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 until a recovery of the cost basis.

At September 30, 2018 and December 31, 2017, the contractual maturities of our investments did not exceed 36 months. The fair values of available-for-sale investment securities, by remaining contractual maturity, are as follows (in thousands):



	September 30, 2018				December 31, 2017
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Due in one year or less	$	31,949	$	31,823	$	29,850	$	29,800
Due after one year through three years	19,967		19,861		22,560		22,401
Total available-for-sale investment securities	$	51,916	$	51,684	$	52,410	$	52,201

During the nine months ended September 30, 2018 and 2017, we had sales and maturities (which includes calls) of investment securities, as follows (in thousands):



	Nine Months Ended September 30, 2018
	Gross Realized Gains		Gross Realized Losses			Gross Proceeds from Sales		Gross Proceeds from Maturities
Corporate bonds	$	—	$	(1	)	$	—	$	16,457
Agency securities	—		—			—		6,000
Certificates of deposit	—		—			—		2,490
Treasury securities	—		—			701		3,530
Total sales and maturities (including calls) of investment securities	$	—	$	(1	)	$	701	$	28,477



	Nine Months Ended September 30, 2017
	Gross Realized Gains		Gross Realized Losses		Gross Proceeds from Sales		Gross Proceeds from Maturities
Corporate bonds	$	—	$	—	$	—	$	7,440
Agency securities	1		—		15		1,044
Certificates of deposit	—		—		—		2,490
Total sales and maturities (including calls) of investment securities	$	1	$	—	$	15	$	10,974

Interest income, net of the amortization and accretion of the premium and discount, for the three months ended September 30, 2018 and 2017, was $0.3 million and $0.2 million, respectively and $0.8 million and $0.5 million for the nine months ended September 30, 2018 and 2017, 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 measured at fair value on a recurring basis as of September 30, 2018 and December 31, 2017, by level within the fair value hierarchy (in thousands):



	September 30, 2018
	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	865	$	—	$	—	$	865
Available-for-sale investment securities:
Corporate bonds	—		33,060		—		33,060
Agency securities	—		10,238		—		10,238
Certificates of deposit	491		—		—		491
Treasury securities	7,895		—		—		7,895
Total	$	9,251	$	43,298	$	—	$	52,549



	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	$	8,505	$	49,220	$	—	$	57,725

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 financial asset and financial liability fair values on a recurring basis during the nine months ended September 30, 2018. The valuation techniques for the financial assets in the tables above are as follows:

Cash Equivalents

As of September 30, 2018 and December 31, 2017, 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 values of our corporate bonds and agency securities are 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 values of our certificates of deposit and treasury securities are based on market prices for identical assets.

Contingent Consideration

Contingent consideration payable in connection with acquisitions is measured at fair value each period and is based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The valuation of contingent consideration uses assumptions we believe would be made by a market participant. We assess these estimates on an on-going basis as additional data impacting the assumptions become available. We determine the fair value of the contingent consideration using the probability weighted discounted cash flow method.

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 test. For the nine months ended September 30, 2018 and 2017, no impairments were identified on those assets required to be measured at fair value on a non-recurring basis.

Internal-Use Software Development Costs

9 Months Ended

Sep. 30, 2018

Research and Development [Abstract]

Internal-Use Software Development Costs

Internal-use software development costs as of September 30, 2018 and December 31, 2017 were as follows (in thousands):



	September 30, 2018			December 31, 2017
Internal use software development costs, gross	$	54,067		$	44,626
Less: Accumulated amortization	(34,895		)	(27,017		)
Internal use software development costs, net	$	19,172		$	17,609

Capitalized software development costs for the three months ended September 30, 2018 and 2017 were $3.6 million and $2.9 million, respectively, and $9.7 million and $8.4 million for the nine months ended September 30, 2018 and 2017, respectively. Amortization expense with respect to software development costs totaled $2.8 million and $2.3 million for the three months ended September 30, 2018 and 2017, respectively, and $8.1 million and $6.6 million for the nine months ended September 30, 2018 and 2017, respectively.

Future amortization expense with respect to capitalized software development costs as of September 30, 2018 is estimated as follows (in thousands):



Years Ending December 31,
2018	$	2,784
2019	9,294
2020	5,453
2021	1,641
Total amortization expense	$	19,172

Intangible Assets and Goodwill

9 Months Ended

Sep. 30, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets and Goodwill

Intangible assets consisted of the following as of September 30, 2018 and December 31, 2017 (in thousands):



	September 30, 2018
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Weighted Average Useful Life in Years
Customer relationships	$	1,960	$	(641	)	$	1,319	5.0
Technology and database	8,431		(4,504		)	3,927		8.0
Trademarks & trade names	1,300		(613		)	687		9.0
Partner relationships	680		(680		)	—		3.0
Non-compete agreements	100		(41		)	59		4.0
Domain names	273		(273		)	—		5.0
Patents	285		(226		)	59		5.0
Backlog	140		(12		)	128		1.0
	$	13,169	$	(6,990	)	$	6,179	7.0



	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 & trade names	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

Amortization expense with respect to intangible assets for the three months ended September 30, 2018 and 2017 was $0.3 million and $0.4 million, respectively, and $0.9 million and $1.1 million for the nine months ended September 30, 2018 and 2017, respectively.

Future amortization expense with respect to intangible assets as of September 30, 2018 is estimated as follows (in thousands):



Years Ending December 31,
2018	$	285
2019	1,091
2020	904
2021	769
2022	706
Thereafter	2,424
Total amortization expense	$	6,179

Our goodwill balance is solely attributable to acquisitions. There have been no impairment charges recorded against goodwill. The change in the carrying amount of goodwill is as follows (in thousands):



Goodwill as of December 31, 2017	$	6,737
Goodwill from acquisition of WegoWise	8,811
Goodwill as of September 30, 2018	$	15,548

Commitment and Contingencies	9 Months Ended
Commitment and Contingencies	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Obligations As of September 30, 2018, we had operating lease obligations of approximately $27.8 million through 2028. We recorded rent expense of $0.6 million and $0.5 million for the three months ended September 30, 2018 and 2017, respectively, and $1.7 million and $1.5 million for the nine months ended September 30, 2018 and 2017, respectively. On July 27, 2018, we entered into a new lease agreement (the "Lease") with Nassau Land Company, L.P. (the "Landlord"), to lease approximately 86,000 square feet of office space located at 70 Castilian Drive in Santa Barbara, California (the "Premises"), which is directly adjacent to our corporate headquarters. The term of the Lease is 10 years, beginning on September 1, 2018 (the "Commencement Date"), and ending on the tenth anniversary of the Commencement Date. The term may be extended for two additional five year terms at our election. Beginning March 1, 2019, we will pay a base rent of approximately $80,000 per month for 60% of the Premises. Beginning March 1, 2020, we will pay a base rent of approximately $107,000 per month for 80% of the Premises. Beginning June 1, 2020, we will pay a base rent of approximately $134,000 per month for 100% of the Premises. The base rent will increase 3% annually, with the first such increase effective on March 1, 2020. On July 27, 2018, we also entered into a lease amendment for 90 Castilian Drive in Santa Barbara, California. This amendment extends the term of the lease from November 2020 to April 2023. The term may be extended for two additional three year terms at our election. The total commitment under this lease extension is $1.8 million. All other terms and conditions from the original lease and previous amendments remain the same. On September 30, 2018, we entered into a Membership Agreement (the “Membership Agreement”) with WeWork to lease office space located at 7300 Lone Star Drive in Plano, Texas. The term of the Membership Agreement commences on December 1, 2018 and is for a period of 24 months. We will pay a fee of $61,000 per month for the leased premises. Line of Credit We are party to a Credit Agreement with Wells Fargo, as administrative agent, and the lenders that are parties thereto (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”). Borrowings under the Revolving Facility are subject to the satisfaction of customary conditions. 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. As of September 30, 2018 and December 31, 2017, we had no outstanding balance and were in compliance with the financial covenants under the Revolving Facility. Legal Liability to Landlord 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 this insurance service, 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. In cost of revenue, we accrue the expense for reported claims and an estimate of losses incurred but not reported by our property manager customers, as we bear the risk related to all such claims. Our liability for reported claims and incurred but not reported claims as of September 30, 2018 and December 31, 2017 was $0.7 million and $0.5 million, respectively, and is included in Other current liabilities on the Condensed Consolidated Balance Sheets. Included in Other current assets as of September 30, 2018 and December 31, 2017, are $1.1 million and $1.8 million, respectively, of deposits held with a third party related to requirements to maintain collateral for this insurance service. Litigation On September 28, 2017, a putative federal class action styled Leo v. AppFolio, Inc. (Civ. No. 3:17-cv-05771; W.D. Wash.) was filed naming us as a defendant and alleging certain violations of the Fair Credit Reporting Act in connection with our tenant screening Value+ service (the "Leo Litigation"). The parties recently agreed to settle the Leo Litigation and filed a notice of settlement with the court. Key to the settlement is an agreement that we do not admit any liability whatsoever in connection with the claims and allegations in the Leo Litigation. The final settlement agreement will be subject to court approval. As a result of the foregoing developments, we have determined that a loss is probable and therefore recorded an expense, net of expected insurance proceeds, of $1.1 million during the nine months September 30, 2018, within cost of revenue. We expect that our insurer will pay its portion of the settlement proceeds directly to the settlement fund following final court approval. From time to time, we are involved in various other legal proceedings arising from or related to claims incident to the ordinary course of our business activities, including actions with respect to intellectual property, employment and contractual matters. Although the results of such legal proceedings and claims cannot be predicted with certainty, we believe that we are not currently a party to any legal proceeding(s) which, if determined adversely to us, would, individually or taken together, have a material adverse effect on our business, operating results, financial condition or cash flows. 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 and 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 September 30, 2018 and December 31, 2017, we had not accrued a liability for these indemnification arrangements because we determined that the likelihood of incurring any payment obligation, 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.

Stock-Based Compensation

9 Months Ended

Sep. 30, 2018

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

Stock-Based Compensation

Stock Options

A summary of our stock option activity for the nine months ended September 30, 2018, 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, 2017	1,692		$	10.81	7.3
Options granted	—		—
Options exercised	(143	)	5.00
Options cancelled/forfeited	(9	)	15.12
Options outstanding as of September 30, 2018	1,540		$	11.33	6.6

Included in the options outstanding as of September 30, 2018 are 172,000 and 250,000 PSOs granted in 2017 and 2016, respectively. Vesting of these PSOs is based on the achievement of pre-established performance targets for each of the years ending December 31, 2018 and 2019, and continued employment throughout the performance period. Of the PSOs granted during 2017, 132,000 shares vest based on the achievement of a pre-established free cash flow performance target for the year ending December 31, 2019, assuming achievement of the performance metric at the maximum level, which is 150% of the performance target, resulting in a maximum payout of 100% of the initial target award. The remaining 40,000 PSOs granted during 2017 have a pre-established adjusted gross margin target for the year ending December 31, 2019. PSOs tied to the gross margin performance target have two levels of vesting, with 50% vesting based on the achievement of 110% of the targeted amount and the remaining 50% vesting based on the achievement of 115% of the targeted amount. The 250,000 PSOs granted in 2016 vest based on the achievement of a pre-established free cash flow performance target for the year ending December 31, 2018, assuming achievement of the performance metric at the maximum level, which is 150% of the performance target.

During the nine months ended September 30, 2018, 250,000 PSOs vested based on the achievement of 150% of the pre-established free cash flow performance target for the year ended December 31, 2017. No expense was recognized as a result of the vesting of PSOs that vested during the nine months ended September 30, 2018, as all expense was recognized as of 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, including the PSOs, for the three months ended September 30, 2018 and 2017, was $0.6 million and $0.7 million, respectively, and $1.2 million and $2.0 million for the nine months ended September 30, 2018 and 2017, respectively.

The fair value of stock options is estimated on their date of grant using the Black-Scholes option-pricing model. No stock options were granted during the three months ended September 30, 2017 or the three or nine months ended September 30, 2018.

The following table summarizes information relating to our stock options granted during the nine months ended September 30, 2017:



	Nine Months Ended September 30, 2017
Stock options granted (in thousands)	172
Weighted average exercise price per share	$	24.77
Weighted average grant-date fair value per share	$	9.58
Weighted average Black-Scholes model assumptions:
Risk-free interest rate	2.02		%
Expected term (in years)	6.4
Expected volatility	35		%
Expected dividend yield	—

As of September 30, 2018, the total estimated remaining stock-based compensation expense for unvested stock options, including the PSOs, was $1.0 million, which is expected to be recognized over a weighted average period of one year.

Restricted Stock Units

A summary of activity in connection with our RSUs for the nine months ended September 30, 2018 is as follows (number of shares in thousands):



	Number of Shares		Weighted Average Grant Date Fair Value per Share
Unvested as of December 31, 2017	598		$	19.75
Granted	231		44.38
Vested	(168	)	17.34
Forfeited	(45	)	26.12
Unvested as of September 30, 2018	616		$	29.18

During the nine months ended September 30, 2018, we granted a total of 231,000 RSUs: 157,000 RSUs are subject to time-based vesting in equal annual installments over four years; 59,000 PSUs vest based on the achievement of a pre-established consolidated net revenue growth target for each of the years ending December 31, 2018, 2019 and 2020; and 15,000 PSUs were granted and vested as a result of the achievement of a pre-established free cash flow performance target for the year ended December 31, 2017. The number of PSUs granted, as included in the above table, assumes achievement of the performance metric at 100% of the performance target. The actual number of shares to be issued at the end of the performance period will range from 0% to 100% of the initial target awards. Achievement of the performance target between 100% and 150% of the performance target will result in a performance based cash bonus payment between 100% and 165% of the initial target awards.

During the nine months ended September 30, 2018, 30,000 of the PSUs vested and an additional 15,000 PSUs were granted and vested based on the achievement of 150% of the pre-established free cash flow performance target for the year ended December 31, 2017. No expense was recognized related to the PSUs that vested during the nine months ended September 30, 2018, as all expense was recognized as of December 31, 2017.

Included in the unvested RSUs as of September 30, 2018 are 91,000 and 26,000 PSUs granted in 2017 and 2016, respectively. Vesting of these PSUs is based on the achievement of pre-established free cash flow performance targets for each of the years ending December 31, 2018 and 2019, and continued employment throughout the performance period. The number of PSUs granted assumes achievement of the performance metric at 100% of the performance target. For the PSUs granted in 2017, 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 award. For the PSUs granted in 2016, 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 award.

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 three months ended September 30, 2018 and 2017, was $1.3 million and $1.0 million, respectively, and $3.7 million and $2.6 million for the nine months ended September 30, 2018 and 2017, respectively.

As of September 30, 2018, the total estimated remaining stock-based compensation expense for the RSUs and PSUs was $12.2 million, which is expected to be recognized over a weighted average period of 2.3 years.

Restricted Stock Awards

A summary of activity in connection with our restricted stock awards for the nine months ended September 30, 2018, is as follows (number of shares in thousands):



	Number of Shares		Weighted Average Grant Date Fair Value per Share
Unvested as of December 31, 2017	16		$	20.93
Granted	5		61.05
Vested	(14	)	23.83
Forfeited	—		—
Unvested as of September 30, 2018	7		$	41.86

We have the right to repurchase any unvested restricted stock awards subject to certain conditions. Restricted stock awards vest over a four-year period for employees and a one-year period for non-employee directors. We recognized stock-based compensation expense for restricted stock awards of $84,000 for each of the three months ended September 30, 2018 and 2017, and $250,000 and $274,000 for the nine months ended September 30, 2018 and 2017, respectively.

As of September 30, 2018, the total estimated remaining stock-based compensation expense for unvested restricted stock awards with a repurchasing right was $234,000 which is expected to be recognized over a weighted average period of 0.7 years.

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes 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. Our effective tax rate differs from the United States federal statutory rate of 21% primarily because our previously reported losses have been offset by a valuation allowance due to uncertainty as to the realization of those losses. For the three and nine months ended September 30, 2018, we recorded income tax expense of $183,000 and $252,000, respectively, on pre-tax income of $5.7 million and $17.6 million, respectively, for an effective tax rate of 3.2% and 1.4%, respectively. The income tax expense is based on our payments of state minimum and franchise taxes, and the amortization of tax deductible goodwill that is not an available source of income to realize the deferred tax asset. For the three and nine months ended September 30, 2017, we recorded income tax expense of $52,000 and $93,000, respectively, on pre-tax income of $3.7 million and $7.2 million, respectively, for an effective tax rate of 1.4% and 1.3%, respectively. The income tax expense is based on our payments of state minimum taxes, alternative minimum tax ("AMT") (net of available AMT credit), and the amortization of tax deductible goodwill that is not an available source of income to realize the deferred tax asset. We have recorded a full valuation allowance related to our NOLs, credit carryforwards, and other net deferred tax assets due to the uncertainty of the ultimate realization of the future benefits of those assets. To the extent we determine that all, or a portion of, our valuation allowance is no longer necessary, we will reverse the valuation allowance and recognize an income tax benefit in the reported financial statement earnings in that period. Once the valuation allowance is eliminated or reduced, its reversal will no longer be available to offset our current financial statement tax provision in future periods. We believe that there is a possibility that, within the next twelve months, sufficient positive evidence may become available to allow us to reach a conclusion that some or all of the valuation allowance will no longer be needed. Release of the valuation allowance would result in the recognition of certain net deferred tax assets and a decrease to income tax expense for the period the release is recorded. However, the timing and amount of the valuation allowance release are subject to change on the basis of the level of company profitability and other factors.

Revenue and Other Information

9 Months Ended

Sep. 30, 2018

Segment Reporting [Abstract]

Revenue and Other Information

The following table presents our revenue categories for the three and nine months ended September 30, 2018 and 2017 (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Core solutions	$	17,908	$	14,670	$	51,101	$	41,682
Value+ services	30,797		21,752		84,189		60,053
Other	1,421		1,481		4,416		4,171
Total revenues	$	50,126	$	37,903	$	139,706	$	105,906

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

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2018

Accounting Policies [Abstract]

Basis of Presentation and Significant Accounting Policies

Revenue Recognition and Deferred Costs

Revenue Recognition

Core Solutions

Value+ Services

Other Revenues

Contracts with Multiple Performance Obligations

Deferred Revenues

Deferred Costs

Use of Estimates

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

The cumulative effects of the changes made to our Condensed Consolidated Balance Sheet at January 1, 2018 for the adoption of the New Revenue Standard were as follows (in thousands):



	Balance at December 31, 2017			Adjustments		Balance at January 1, 2018
Assets
Prepaid expenses and other current assets	$	4,546		$	1,148	$	5,694
Other assets	1,238			1,816		3,054

Equity
Accumulated deficit	$	(67,247	)	$	2,964	$	(64,283	)

The following tables summarize the current period impacts of adopting the New Revenue Standard on our Condensed Consolidated Financial Statements (in thousands):

Condensed Consolidated Balance Sheet:



	September 30, 2018
	As Reported			Balances Without Adoption of ASU 2014-09			Effect of Adoption
Assets
Prepaid expenses and other current assets	$	10,916		$	8,381		$	2,535
Other assets	6,757			3,486			3,271

Equity
Accumulated deficit	$	(46,965	)	$	(52,772	)	$	5,807

Condensed Consolidated Statements of Operations:



	Three Months Ended September 30, 2018							Nine Months Ended September 30, 2018
	As Reported		Balances Without Adoption of ASU 2014-09		Effect of Adoption			As Reported		Balances Without Adoption of ASU 2014-09		Effect of Adoption
Costs and operating expenses:
Cost of revenue (exclusive of depreciation and amortization)	$	19,282	$	19,342	$	(60	)	$	53,624	$	53,806	$	(182	)
Sales and marketing	8,681		9,540		(859		)	23,711		26,371		(2,660		)
Total costs and operating expenses	44,649		45,568		(919		)	122,747		125,589		(2,842		)
Income from operations	5,477		4,558		919			16,959		14,117		2,842
Income before provision for income taxes	5,707		4,788		919			17,570		14,728		2,842
Net income	$	5,524	$	4,605	$	919		$	17,318	$	14,476	$	2,842

Net income per common share:
Basic	$	0.16	$	0.13	$	0.03		$	0.51	$	0.42	$	0.09
Diluted	$	0.16	$	0.13	$	0.03		$	0.49	$	0.41	$	0.08

Recent Accounting Pronouncements Not Yet Adopted

Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2018

Accounting Policies [Abstract]

Schedule of Weighted Average Number of Shares

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



	Three Months Ended September 30,		Nine Months Ended September 30,
	2018	2017	2018	2017
Weighted average common shares outstanding	34,227	33,923	34,166	33,848
Less: Weighted average unvested restricted shares subject to repurchase	8	18	12	31
Weighted average common shares outstanding; basic	34,219	33,905	34,154	33,817
Plus: Weighted average options, restricted stock units and restricted shares used to compute diluted net income per common share	1,391	1,300	1,370	1,274
Weighted average common shares outstanding; diluted	35,610	35,205	35,524	35,091

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share



	Three Months Ended September 30,		Nine Months Ended September 30,
	2018	2017	2018	2017
Unvested restricted stock units	3	13	3	13
Contingent restricted stock units⁽¹⁾	1	6	1	6
Total shares excluded from diluted net income per common share	4	19	4	19

Schedule of Impact of Adoption of New Revenue Standard Impact on Financial Statements

The cumulative effects of the changes made to our Condensed Consolidated Balance Sheet at January 1, 2018 for the adoption of the New Revenue Standard were as follows (in thousands):



	Balance at December 31, 2017			Adjustments		Balance at January 1, 2018
Assets
Prepaid expenses and other current assets	$	4,546		$	1,148	$	5,694
Other assets	1,238			1,816		3,054

Equity
Accumulated deficit	$	(67,247	)	$	2,964	$	(64,283	)

The following tables summarize the current period impacts of adopting the New Revenue Standard on our Condensed Consolidated Financial Statements (in thousands):

Condensed Consolidated Balance Sheet:



	September 30, 2018
	As Reported			Balances Without Adoption of ASU 2014-09			Effect of Adoption
Assets
Prepaid expenses and other current assets	$	10,916		$	8,381		$	2,535
Other assets	6,757			3,486			3,271

Equity
Accumulated deficit	$	(46,965	)	$	(52,772	)	$	5,807

Condensed Consolidated Statements of Operations:



	Three Months Ended September 30, 2018							Nine Months Ended September 30, 2018
	As Reported		Balances Without Adoption of ASU 2014-09		Effect of Adoption			As Reported		Balances Without Adoption of ASU 2014-09		Effect of Adoption
Costs and operating expenses:
Cost of revenue (exclusive of depreciation and amortization)	$	19,282	$	19,342	$	(60	)	$	53,624	$	53,806	$	(182	)
Sales and marketing	8,681		9,540		(859		)	23,711		26,371		(2,660		)
Total costs and operating expenses	44,649		45,568		(919		)	122,747		125,589		(2,842		)
Income from operations	5,477		4,558		919			16,959		14,117		2,842
Income before provision for income taxes	5,707		4,788		919			17,570		14,728		2,842
Net income	$	5,524	$	4,605	$	919		$	17,318	$	14,476	$	2,842

Net income per common share:
Basic	$	0.16	$	0.13	$	0.03		$	0.51	$	0.42	$	0.09
Diluted	$	0.16	$	0.13	$	0.03		$	0.49	$	0.41	$	0.08

Acquisition of WegoWise (Tables)

9 Months Ended

Sep. 30, 2018

Business Combinations [Abstract]

Schedule of Purchase Price Allocation

The following table summarizes the purchase price allocation (in thousands) as well as the estimated useful lives of the acquired intangible assets over which they are amortized on a straight-line basis, as this approximates the pattern in which economic benefits are consumed:



	Amount		Estimated Useful Life (in years)
Net assets	$	270
Identified intangible assets:
Customer relationships	1,170		5.0
Technology and database	3,620		10.0
Trademark and trade name	370		10.0
Non-compete agreement	60		5.0
Backlog	140		1.0
Total intangible assets subject to amortization	5,360		8.6
Goodwill	8,811		Indefinite
Purchase consideration, paid in cash	$	14,441

Schedule of Pro Forma Information

The unaudited pro forma results are as follows (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Revenue	$	50,850	$	38,653	$	142,158	$	108,172
Net income	$	5,484	$	2,423	$	15,444	$	3,493

Net income per common share:
Basic	$	0.16	$	0.07	$	0.45	$	0.10
Diluted	$	0.15	$	0.07	$	0.43	$	0.10

Investment Securities and Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2018

Fair Value Disclosures [Abstract]

Schedule of Available-for-sale Securities

Investment securities classified as available-for-sale consisted of the following at September 30, 2018 and December 31, 2017 (in thousands):



	September 30, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Corporate bonds	$	33,239	$	1	$	(180	)	$	33,060
Agency securities	10,283		—		(45		)	10,238
Certificates of deposit	492		—		(1		)	491
Treasury securities	7,902		—		(7		)	7,895
Total available-for-sale investment securities	$	51,916	$	1	$	(233	)	$	51,684



	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

Available-for-sale Investments, by Remaining Contract Maturity

The fair values of available-for-sale investment securities, by remaining contractual maturity, are as follows (in thousands):



	September 30, 2018				December 31, 2017
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Due in one year or less	$	31,949	$	31,823	$	29,850	$	29,800
Due after one year through three years	19,967		19,861		22,560		22,401
Total available-for-sale investment securities	$	51,916	$	51,684	$	52,410	$	52,201

Schedule of Sales, Calls, and Maturities

During the nine months ended September 30, 2018 and 2017, we had sales and maturities (which includes calls) of investment securities, as follows (in thousands):



	Nine Months Ended September 30, 2018
	Gross Realized Gains		Gross Realized Losses			Gross Proceeds from Sales		Gross Proceeds from Maturities
Corporate bonds	$	—	$	(1	)	$	—	$	16,457
Agency securities	—		—			—		6,000
Certificates of deposit	—		—			—		2,490
Treasury securities	—		—			701		3,530
Total sales and maturities (including calls) of investment securities	$	—	$	(1	)	$	701	$	28,477



	Nine Months Ended September 30, 2017
	Gross Realized Gains		Gross Realized Losses		Gross Proceeds from Sales		Gross Proceeds from Maturities
Corporate bonds	$	—	$	—	$	—	$	7,440
Agency securities	1		—		15		1,044
Certificates of deposit	—		—		—		2,490
Total sales and maturities (including calls) of investment securities	$	1	$	—	$	15	$	10,974

Fair Value, Assets Measured on Recurring Basis

The following tables summarize our financial assets measured at fair value on a recurring basis as of September 30, 2018 and December 31, 2017, by level within the fair value hierarchy (in thousands):



	September 30, 2018
	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	865	$	—	$	—	$	865
Available-for-sale investment securities:
Corporate bonds	—		33,060		—		33,060
Agency securities	—		10,238		—		10,238
Certificates of deposit	491		—		—		491
Treasury securities	7,895		—		—		7,895
Total	$	9,251	$	43,298	$	—	$	52,549



	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	$	8,505	$	49,220	$	—	$	57,725

Internal-Use Software Development Costs (Tables)

9 Months Ended

Sep. 30, 2018

Research and Development [Abstract]

Schedule of Capitalized Computer Software

Internal-use software development costs as of September 30, 2018 and December 31, 2017 were as follows (in thousands):



	September 30, 2018			December 31, 2017
Internal use software development costs, gross	$	54,067		$	44,626
Less: Accumulated amortization	(34,895		)	(27,017		)
Internal use software development costs, net	$	19,172		$	17,609

Schedule of Capitalized Computer Software Future Amortization Expense

Future amortization expense with respect to capitalized software development costs as of September 30, 2018 is estimated as follows (in thousands):



Years Ending December 31,
2018	$	2,784
2019	9,294
2020	5,453
2021	1,641
Total amortization expense	$	19,172

Intangible Assets and Goodwill (Tables)

9 Months Ended

Sep. 30, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Finite-Lived Intangible Assets

Intangible assets consisted of the following as of September 30, 2018 and December 31, 2017 (in thousands):



	September 30, 2018
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Weighted Average Useful Life in Years
Customer relationships	$	1,960	$	(641	)	$	1,319	5.0
Technology and database	8,431		(4,504		)	3,927		8.0
Trademarks & trade names	1,300		(613		)	687		9.0
Partner relationships	680		(680		)	—		3.0
Non-compete agreements	100		(41		)	59		4.0
Domain names	273		(273		)	—		5.0
Patents	285		(226		)	59		5.0
Backlog	140		(12		)	128		1.0
	$	13,169	$	(6,990	)	$	6,179	7.0



	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 & trade names	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

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense

Future amortization expense with respect to intangible assets as of September 30, 2018 is estimated as follows (in thousands):



Years Ending December 31,
2018	$	285
2019	1,091
2020	904
2021	769
2022	706
Thereafter	2,424
Total amortization expense	$	6,179

Schedule of Goodwill

The change in the carrying amount of goodwill is as follows (in thousands):



Goodwill as of December 31, 2017	$	6,737
Goodwill from acquisition of WegoWise	8,811
Goodwill as of September 30, 2018	$	15,548

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2018

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

Summary of Stock Option Activity

A summary of our stock option activity for the nine months ended September 30, 2018, 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, 2017	1,692		$	10.81	7.3
Options granted	—		—
Options exercised	(143	)	5.00
Options cancelled/forfeited	(9	)	15.12
Options outstanding as of September 30, 2018	1,540		$	11.33	6.6

Schedule of Valuation Assumptions, Stock Options

The following table summarizes information relating to our stock options granted during the nine months ended September 30, 2017:



	Nine Months Ended September 30, 2017
Stock options granted (in thousands)	172
Weighted average exercise price per share	$	24.77
Weighted average grant-date fair value per share	$	9.58
Weighted average Black-Scholes model assumptions:
Risk-free interest rate	2.02		%
Expected term (in years)	6.4
Expected volatility	35		%
Expected dividend yield	—

Schedule of Restricted Stock Units Activity

A summary of activity in connection with our RSUs for the nine months ended September 30, 2018 is as follows (number of shares in thousands):



	Number of Shares		Weighted Average Grant Date Fair Value per Share
Unvested as of December 31, 2017	598		$	19.75
Granted	231		44.38
Vested	(168	)	17.34
Forfeited	(45	)	26.12
Unvested as of September 30, 2018	616		$	29.18

Schedule of Restricted Stock Awards Activity

A summary of activity in connection with our restricted stock awards for the nine months ended September 30, 2018, is as follows (number of shares in thousands):



	Number of Shares		Weighted Average Grant Date Fair Value per Share
Unvested as of December 31, 2017	16		$	20.93
Granted	5		61.05
Vested	(14	)	23.83
Forfeited	—		—
Unvested as of September 30, 2018	7		$	41.86

Revenue and Other Information (Tables)

9 Months Ended

Sep. 30, 2018

Segment Reporting [Abstract]

Schedule of Product Information by Revenue Categories

The following table presents our revenue categories for the three and nine months ended September 30, 2018 and 2017 (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Core solutions	$	17,908	$	14,670	$	51,101	$	41,682
Value+ services	30,797		21,752		84,189		60,053
Other	1,421		1,481		4,416		4,171
Total revenues	$	50,126	$	37,903	$	139,706	$	105,906

Nature of Business (Details)	9 Months Ended
Nature of Business (Details)	Sep. 30, 2018
Property Management
Business Acquisition [Line Items]
Revenue percentage	90.00%
Legal Services
Business Acquisition [Line Items]
Revenue percentage	10.00%

Summary of Significant Accounting Policies - Revenue Recognition and Deferred Costs Narrative (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Deferred revenue, revenue recognized		$ 6,700,000
Deferred costs amortization term		3 years
Deferred contract costs	$ 5,800,000	$ 5,800,000
Deferred contract costs, current	2,500,000	2,500,000
Deferred contract costs, noncurrent	3,300,000	3,300,000
Amortization of contract costs	$ 500,000	1,300,000
Capitalized costs impairments		$ 0
Core solutions \| Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Subscription agreement term		one month
Core solutions \| Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Subscription agreement term		one year

Summary of Significant Accounting Policies - Net Income per Share Schedule of Weighted Average Number of Shares (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average common shares outstanding (in shares)	34,227	33,923	34,166	33,848
Less: Weighted average unvested restricted shares subject to repurchase (in shares)	8	18	12	31
Weighted average common shares outstanding; basic (in shares)	34,219	33,905	34,154	33,817
Plus: Weighted average options, restricted stock units and restricted shares used to compute diluted net income per common share (in shares)	1,391	1,300	1,370	1,274
Weighted average common shares outstanding; diluted (in shares)	35,610	35,205	35,524	35,091
Shares excluded from net loss per share attributable to common stockholders (in shares)	4	19	4	19
PSUs and PSOs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from net loss per share attributable to common stockholders (in shares)	503	571	503	571

Summary of Significant Accounting Policies - Net (Income) Loss Schedule of Antidilutive Securities (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from net income (loss) per common share (in shares)	4	19	4	19
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from net income (loss) per common share (in shares)	3	13	3	13
Contingent restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from net income (loss) per common share (in shares)	1	6	1	6

Summary of Significant Accounting Policies - Impact of Adoption of New Revenue Standard on the Condensed Consolidated Balance Sheet and Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Assets
Prepaid expenses and other current assets	$ 10,916		$ 10,916		$ 5,694	$ 4,546
Other assets	6,757		6,757		3,054	1,238
Equity
Accumulated deficit	(46,965)		(46,965)		(64,283)	(67,247)
Costs and operating expenses:
Cost of revenue (exclusive of depreciation and amortization)	19,282	$ 14,053	53,624	$ 40,747
Sales and marketing	8,681	7,257	23,711	21,556
Total costs and operating expenses	44,649	34,319	122,747	98,958
Income from operations	5,477	3,584	16,959	6,948
Income before provision for income taxes	5,707	3,734	17,570	7,232
Net income	$ 5,524	$ 3,682	$ 17,318	$ 7,139
Net income per common share:
Basic (usd per share)	$ 0.16	$ 0.11	$ 0.51	$ 0.21
Diluted (usd per share)	$ 0.16	$ 0.10	$ 0.49	$ 0.20
Calculated under Revenue Guidance in Effect before Topic 606
Assets
Prepaid expenses and other current assets	$ 8,381		$ 8,381			4,546
Other assets	3,486		3,486			1,238
Equity
Accumulated deficit	(52,772)		(52,772)			$ (67,247)
Costs and operating expenses:
Cost of revenue (exclusive of depreciation and amortization)	19,342		53,806
Sales and marketing	9,540		26,371
Total costs and operating expenses	45,568		125,589
Income from operations	4,558		14,117
Income before provision for income taxes	4,788		14,728
Net income	$ 4,605		$ 14,476
Net income per common share:
Basic (usd per share)	$ 0.13		$ 0.42
Diluted (usd per share)	$ 0.13		$ 0.41
Difference between Revenue Guidance in Effect before and after Topic 606 \| Accounting Standards Update 2014-09
Assets
Prepaid expenses and other current assets	$ 2,535		$ 2,535		1,148
Other assets	3,271		3,271		1,816
Equity
Accumulated deficit	5,807		5,807		$ 2,964
Costs and operating expenses:
Cost of revenue (exclusive of depreciation and amortization)	(60)		(182)
Sales and marketing	(859)		(2,660)
Total costs and operating expenses	(919)		(2,842)
Income from operations	919		2,842
Income before provision for income taxes	919		2,842
Net income	$ 919		$ 2,842
Net income per common share:
Basic (usd per share)	$ 0.03		$ 0.09
Diluted (usd per share)	$ 0.03		$ 0.08

Acquisition of WegoWise (Details) - USD ($) $ in Thousands		1 Months Ended
Acquisition of WegoWise (Details) - USD ($) $ in Thousands	Aug. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill		$ 15,548	$ 6,737
WegoWise, Inc.
Business Acquisition [Line Items]
Consideration total, gross	$ 14,400
Escrow consideration	2,000
Net assets	270
Identified intangible assets	5,360
Goodwill	8,811
Purchase consideration, paid in cash	$ 14,441
Estimated Useful Life (in years)	8 years 7 months 10 days
Acquisition related expenses		210
Revenue from acquiree		79
Net income (loss) from acquiree		$ (329)
WegoWise, Inc. \| Customer relationships
Business Acquisition [Line Items]
Identified intangible assets	$ 1,170
Estimated Useful Life (in years)	5 years
WegoWise, Inc. \| Technology
Business Acquisition [Line Items]
Identified intangible assets	$ 3,620
Estimated Useful Life (in years)	10 years
WegoWise, Inc. \| Trademark and trade name
Business Acquisition [Line Items]
Identified intangible assets	$ 370
Estimated Useful Life (in years)	10 years
WegoWise, Inc. \| Non-compete agreements
Business Acquisition [Line Items]
Identified intangible assets	$ 60
Estimated Useful Life (in years)	5 years
WegoWise, Inc. \| Backlog
Business Acquisition [Line Items]
Identified intangible assets	$ 140
Estimated Useful Life (in years)	1 year

Acquisition of WegoWise - Pro Forma Information (Details) - WegoWise, Inc. - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Business Acquisition [Line Items]
Revenue	$ 50,850	$ 38,653	$ 142,158	$ 108,172
Net income	$ 5,484	$ 2,423	$ 15,444	$ 3,493
Net income per common share:
Basic (in dollars per share)	$ 0.16	$ 0.07	$ 0.45	$ 0.10
Diluted (in dollars per share)	$ 0.15	$ 0.07	$ 0.43	$ 0.10

Investment Securities and Fair Value Measurements - Investment Securities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Available-for-sale Securities, Amortized Cost Basis [Abstract] (Deprecated 2018-01-31)
Total available-for-sale investment securities	$ 51,916	$ 52,410
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(233)	(210)
Estimated Fair Value	$ 51,684	$ 52,201
Maximum contractual maturity period	36 months	36 months
Amortized Cost
Due in 1 year or less	$ 31,949	$ 29,850
Due after 1 year through 3 years	19,967	22,560
Total available-for-sale investment securities	51,916	52,410
Estimated Fair Value
Due in one year or less	31,823	29,800
Due after one year through three years	19,861	22,401
Total available-for-sale investment securities	51,684	52,201
Corporate bonds
Available-for-sale Securities, Amortized Cost Basis [Abstract] (Deprecated 2018-01-31)
Total available-for-sale investment securities	33,239	38,383
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(180)	(166)
Estimated Fair Value	33,060	38,217
Amortized Cost
Total available-for-sale investment securities	33,239	38,383
Estimated Fair Value
Total available-for-sale investment securities	33,060	38,217
Agency securities
Available-for-sale Securities, Amortized Cost Basis [Abstract] (Deprecated 2018-01-31)
Total available-for-sale investment securities	10,283	11,045
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(45)	(42)
Estimated Fair Value	10,238	11,003
Amortized Cost
Total available-for-sale investment securities	10,283	11,045
Estimated Fair Value
Total available-for-sale investment securities	10,238	11,003
Certificates of deposit
Available-for-sale Securities, Amortized Cost Basis [Abstract] (Deprecated 2018-01-31)
Total available-for-sale investment securities	492	2,982
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(1)	(2)
Estimated Fair Value	491	2,981
Amortized Cost
Total available-for-sale investment securities	492	2,982
Estimated Fair Value
Total available-for-sale investment securities	491	$ 2,981
Treasury securities
Available-for-sale Securities, Amortized Cost Basis [Abstract] (Deprecated 2018-01-31)
Total available-for-sale investment securities	7,902
Gross Unrealized Gains	0
Gross Unrealized Losses	(7)
Estimated Fair Value	7,895
Amortized Cost
Total available-for-sale investment securities	7,902
Estimated Fair Value
Total available-for-sale investment securities	$ 7,895

Investment Securities and Fair Value Measurements - Sales, Calls and Maturities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Debt Securities, Available-for-sale [Line Items]
Gross Realized Gains			$ 0	$ 1
Gross Realized Losses			(1)	0
Sales of investment securities			701	15
Gross Proceeds from Maturities			28,477	10,974
Accretion (amortization) of discounts and premiums	$ 300	$ 200	800	500
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Gross Realized Gains			0	0
Gross Realized Losses			(1)	0
Sales of investment securities			0	0
Gross Proceeds from Maturities			16,457	7,440
Agency securities
Debt Securities, Available-for-sale [Line Items]
Gross Realized Gains			0	1
Gross Realized Losses			0	0
Sales of investment securities			0	15
Gross Proceeds from Maturities			6,000	1,044
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Gross Realized Gains			0	0
Gross Realized Losses			0	0
Sales of investment securities			0	0
Gross Proceeds from Maturities			2,490	$ 2,490
Treasury securities
Debt Securities, Available-for-sale [Line Items]
Gross Realized Gains			0
Gross Realized Losses			0
Sales of investment securities			701
Gross Proceeds from Maturities			$ 3,530

Internal-Use Software Development Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Research and Development [Abstract]
Internal use software development costs, gross	$ 54,067		$ 54,067		$ 44,626
Less: Accumulated amortization	(34,895)		(34,895)		(27,017)
Internal use software development costs, net	19,172		19,172		$ 17,609
Capitalized software development costs during the period	3,600	$ 2,900	9,700	$ 8,400
Amortization expense with respect to software development costs during the period	$ 2,800	$ 2,300	$ 8,100	$ 6,600

Internal-Use Software Development Costs - Capitalized Computer Software Future Amortization Expense (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Research and Development [Abstract]
2018	$ 2,784
2019	9,294
2020	5,453
2021	1,641
Internal use software development costs, net	$ 19,172	$ 17,609

Intangible Assets and Goodwill - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2015	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 13,169		$ 13,169			$ 7,809
Accumulated Amortization	(6,990)		(6,990)			(6,084)
Net Carrying Value	6,179		6,179			1,725
Amortization expense	300	$ 400	$ 900	$ 1,100
Weighted average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life in Years			7 years 4 days		5 years 10 months 28 days
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,960		$ 1,960			790
Accumulated Amortization	(641)		(641)			(538)
Net Carrying Value	1,319		$ 1,319			252
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	8,431		$ 8,431			4,811
Accumulated Amortization	(4,504)		(4,504)			(3,871)
Net Carrying Value	3,927		$ 3,927			940
Technology \| Weighted average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life in Years			8 years		6 years
Trademark and trade name
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,300		$ 1,300			930
Accumulated Amortization	(613)		(613)			(539)
Net Carrying Value	687		$ 687			391
Trademark and trade name \| 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			680
Accumulated Amortization	(680)		(680)			(623)
Net Carrying Value	0		$ 0			57
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	100		$ 100			40
Accumulated Amortization	(41)		(41)			(37)
Net Carrying Value	59		$ 59			3
Non-compete agreements \| Weighted average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life in Years			4 years		3 years
Domain names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	273		$ 273			273
Accumulated Amortization	(273)		(273)			(273)
Net Carrying Value	0		$ 0			0
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		$ 285			285
Accumulated Amortization	(226)		(226)			(203)
Net Carrying Value	59		$ 59			$ 82
Patents \| Weighted average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life in Years			5 years		5 years
Backlog
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	140		$ 140
Accumulated Amortization	(12)		(12)
Net Carrying Value	$ 128		$ 128
Backlog \| Weighted average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life in Years			1 year

Intangible Assets and Goodwill - Future Amortization (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2018	$ 285
2019	1,091
2020	904
2021	769
2022	706
Thereafter	2,424
Net Carrying Value	$ 6,179	$ 1,725

Intangible Assets and Goodwill - Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($)
Goodwill [Roll Forward]
Goodwill as of December 31, 2017	$ 6,737
Goodwill from acquisition of WegoWise	8,811
Goodwill as of September 30, 2018	$ 15,548

Commitment and Contingencies (Details) ft² in Thousands			3 Months Ended		9 Months Ended
Commitment and Contingencies (Details) ft² in Thousands	Sep. 30, 2018 USD ($)	Jul. 27, 2018 USD ($) ft² extension_term	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Loss Contingencies [Line Items]
Operating lease obligations	$ 27,800,000		$ 27,800,000		$ 27,800,000
Rent expense			600,000	$ 500,000	1,700,000	$ 1,500,000
Area of office space rented (in square feet) \| ft²		86
Lease term		10 years
Number of extension terms \| extension_term		2
Lease renewal term		5 years
Monthly rental expense for 60% of the Premises		$ 80,000
Monthly rental expense for 80% of the Premises		107,000
Monthly rental expense for 100% of the Premises		$ 134,000
Annual base rate increase, percent		3.00%
Per incident policy limit					$ 100,000
Quota share of tenant liability insurance provided, percent					100.00%
Leo v. AppFolio, Inc.
Loss Contingencies [Line Items]
Expense, net of expected insurance proceeds			1,100,000
Other current liabilities
Loss Contingencies [Line Items]
Liability for reported claims and claims incurred but not reported	700,000		700,000		$ 700,000		$ 500,000
Other current assets
Loss Contingencies [Line Items]
Deposits held with a third party related to insurance services collateral	1,100,000		1,100,000		1,100,000		1,800,000
Credit Facility \| Revolving Facility
Loss Contingencies [Line Items]
Maximum borrowing capacity	25,000,000		25,000,000		25,000,000
Credit Facility \| Term Loan
Loss Contingencies [Line Items]
Line of credit, amount outstanding	0		$ 0		$ 0		$ 0
Lease on 90 Castilian Drive, Santa Barbara, California
Loss Contingencies [Line Items]
Operating lease obligations		$ 1,800,000
Number of extension terms \| extension_term		2
Lease renewal term		3 years
Lease on 7300 Lone Star Drive in Plano, Texas
Loss Contingencies [Line Items]
Rent expense	$ 61,000

Stock-Based Compensation - Stock Option Activity (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding, beginning balance (shares)			1,692,000
Options granted (shares)	0	0	0	172,000
Options exercised (shares)			(143,000)
Options cancelled/forfeited (shares)			(9,000)
Options outstanding, ending balance (shares)	1,540,000		1,540,000		1,692,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Options outstanding, weighted average exercise price, beginning balance (usd per share)			$ 10.81
Options granted, weighted average exercise price (usd per share)			0.00	$ 24.77
Options exercised, weighted average exercise price (usd per share)			5.00
Options cancelled/forfeited, weighted average exercise price (usd per share)			15.12
Options outstanding, weighted average exercise price, ending balance (usd per share)	$ 11.33		$ 11.33		$ 10.81
Weighted average remaining contractual life, in years			6 years 7 months 6 days		7 years 3 months 18 days
Stock Options and PSOs
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Stock-based compensation expense	$ 600,000	$ 700,000	$ 1,200,000	$ 2,000,000
PSOs \| 2019 and 2018 Performance Metric Granted in 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding, ending balance (shares)	172,000		172,000
PSOs \| 2018 Performance Metric Granted in 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options granted (shares)			250,000
Options outstanding, ending balance (shares)	250,000		250,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Percent of targeted performance metric	150.00%		150.00%
PSOs \| 2019 Performance Metric, Targeted Free Cash Flow Performance Metric
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options granted (shares)			132,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Percent of targeted awards that will vest	150.00%		150.00%
Percent of targeted performance metric	100.00%		100.00%
PSOs \| 2019 Performance Metric, Adjusted Gross Margin Target
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options granted (shares)			40,000
PSOs \| 2019 Performance Metric, Adjusted Gross Margin Target \| Vesting Tranche One
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Percent of targeted awards that will vest	110.00%		110.00%
Percent of targeted performance metric	50.00%		50.00%
PSOs \| 2019 Performance Metric, Adjusted Gross Margin Target \| Vesting Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Percent of targeted awards that will vest	115.00%		115.00%
Percent of targeted performance metric	50.00%		50.00%
PSOs \| 2017 Performance Metric, Targeted Free Cash Flow Performance Metric
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Share-based compensation options vested (shares)			250,000
Percent of achievement of award target performance metric	150.00%		150.00%
PSOs \| 2017 Performance Metric
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Stock-based compensation expense			$ 0

Stock-Based Compensation - Valuation Assumptions (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (shares)	0	0	0	172,000
Options granted, weighted average exercise price (usd per share)			$ 0.00	$ 24.77
Weighted average grant-date fair value per share (usd per share)				$ 9.58
Stock Options and PSOs
Weighted average Black-Scholes model assumptions:
Risk-free interest rate				2.02%
Expected term (in years)				6 years 4 months 24 days
Expected volatility				35.00%
Expected dividend yield				0.00%
Remaining stock-based compensation expense for unvested options, not yet recognized	$ 1.0		$ 1.0
Stock-based compensation expense, weighted average recognition period			1 year

Stock-Based Compensation - Restricted Stock Units Activity (Details) - RSUs and PSUs shares in Thousands	9 Months Ended
	Sep. 30, 2018 $ / shares shares
Number of Shares
Unvested, beginning balance (shares) \| shares	598
Granted (shares) \| shares	231
Vested (shares) \| shares	(168)
Forfeited (shares) \| shares	(45)
Unvested, ending balance (shares) \| shares	616
Weighted- Average Grant Date Fair Value per Share
Unvested, beginning balance (usd per share) \| $ / shares	$ 19.75
Granted (usd per share) \| $ / shares	44.38
Vested (usd per share) \| $ / shares	17.34
Forfeited (usd per share) \| $ / shares	26.12
Unvested, ending balance (usd per share) \| $ / shares	$ 29.18

Stock-Based Compensation - Restricted Stock Units (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
RSUs and PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in period (shares)			231
Share-based compensation options vested in period (shares)			168
Stock-based compensation expense	$ 1.3	$ 1.0	$ 3.7	$ 2.6
Remaining stock-based compensation expense for unvested shares, not yet recognized	$ 12.2		$ 12.2
Stock-based compensation expense, weighted average recognition period			2 years 3 months 7 days
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in period (shares)			157
Vesting period			4 years
PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in period (shares)			59
Percent of targeted performance metric	100.00%		100.00%
Share-based compensation options vested in period (shares)			30
Percent of achievement of award target performance metric					150.00%
PSUs \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of targeted performance metric	0.00%		0.00%
PSUs \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of targeted performance metric	100.00%		100.00%
PSUs \| Vesting Tranche One \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of targeted performance metric	100.00%		100.00%
Performance based cash bonus payment percent			100.00%
PSUs \| Vesting Tranche One \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of targeted performance metric	150.00%		150.00%
Performance based cash bonus payment percent			165.00%
PSUs \| 2017 Performance Metric
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in period (shares)			15
PSUs \| 2016 Performance Metric
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in period (shares)					15
PSUs Granted in 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in period (shares)			91
PSUs Granted in 2017 \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of targeted performance metric	0.00%		0.00%
PSUs Granted in 2017 \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of targeted performance metric	165.00%		165.00%
PSUs Granted in 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in period (shares)			26
PSUs Granted in 2016 \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of targeted performance metric	0.00%		0.00%
PSUs Granted in 2016 \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of targeted performance metric	150.00%		150.00%

Stock-Based Compensation - Restricted Stock Awards (Details) - Restricted Stock Awards - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Number of Shares
Unvested, beginning balance (shares)			16
Granted (shares)			5
Vested (shares)			(14)
Forfeited (shares)			0
Unvested, ending balance (shares)	7		7
Weighted Average Grant Date Fair Value per Share
Unvested, beginning balance (usd per share)			$ 20.93
Granted (usd per share)			61.05
Vested (usd per share)			23.83
Forfeited (usd per share)			0.00
Unvested, ending balance (usd per share)	$ 41.86		$ 41.86
Stock-based compensation expense	$ 84	$ 84	$ 250	$ 274
Remaining stock-based compensation expense for unvested shares, not yet recognized	$ 234		$ 234
Stock-based compensation expense, weighted average recognition period			8 months 19 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 (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
U.S Federal statutory rate			21.00%		35.00%
Income tax expense	$ 183	$ 52	$ 252	$ 93
Pre-tax income	$ 5,707	$ 3,734	$ 17,570	$ 7,232
Effective tax rate	3.20%	1.40%	1.40%	1.30%

Revenue and Other Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 50,126	$ 37,903	$ 139,706	$ 105,906
Core solutions
Disaggregation of Revenue [Line Items]
Revenue	17,908	14,670	51,101	41,682
Value plus services
Disaggregation of Revenue [Line Items]
Revenue	30,797	21,752	84,189	60,053
Other
Disaggregation of Revenue [Line Items]
Revenue	$ 1,421	$ 1,481	$ 4,416	$ 4,171

Investment Securities and Fair Value Measurements - Fair Value Measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	$ 51,684	$ 52,201
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	33,060	38,217
Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	10,238	11,003
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	491	2,981
Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	7,895
Fair value, recurring measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	52,549	57,725
Fair value, recurring measurements \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	33,060	38,217
Fair value, recurring measurements \| Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	10,238	11,003
Fair value, recurring measurements \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	491	2,981
Fair value, recurring measurements \| Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	7,895
Fair value, recurring measurements \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	865	5,524
Fair value, recurring measurements \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	9,251	8,505
Fair value, recurring measurements \| Level 1 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair value, recurring measurements \| Level 1 \| Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair value, recurring measurements \| Level 1 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	491	2,981
Fair value, recurring measurements \| Level 1 \| Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	7,895
Fair value, recurring measurements \| Level 1 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	865	5,524
Fair value, recurring measurements \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	43,298	49,220
Fair value, recurring measurements \| Level 2 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	33,060	38,217
Fair value, recurring measurements \| Level 2 \| Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	10,238	11,003
Fair value, recurring measurements \| Level 2 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair value, recurring measurements \| Level 2 \| Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0
Fair value, recurring measurements \| Level 2 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Fair value, recurring measurements \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	0	0
Fair value, recurring measurements \| Level 3 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair value, recurring measurements \| Level 3 \| Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair value, recurring measurements \| Level 3 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair value, recurring measurements \| Level 3 \| Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0
Fair value, recurring measurements \| Level 3 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 0	$ 0