SPS Commerce (SPSC) 10-Q 27 Oct 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 23, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Trading Symbol	SPSC
Entity Registrant Name	SPS COMMERCE INC
Entity Central Index Key	1,092,699
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		17,224,320

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
CURRENT ASSETS
Cash and cash equivalents	$ 128,984	$ 115,877
Short-term marketable securities	34,869	23,076
Accounts receivable, less allowance for doubtful accounts of $878 and $515, respectively	24,175	20,746
Deferred costs	23,326	19,224
Other current assets	5,853	7,010
Total current assets	217,207	185,933
PROPERTY AND EQUIPMENT, net	15,616	15,314
GOODWILL	51,783	49,777
INTANGIBLE ASSETS, net	17,720	19,788
MARKETABLE SECURITIES, non-current	2,491	7,494
OTHER ASSETS
Deferred costs, non-current	6,475	6,086
Deferred income tax asset, non-current	26,628	12,446
Other non-current assets	1,101	1,527
Total assets	339,021	298,365
CURRENT LIABILITIES
Accounts payable	3,089	2,302
Accrued compensation	12,681	13,740
Accrued expenses	3,991	3,508
Deferred revenue	16,209	11,055
Deferred rent	1,655	1,556
Total current liabilities	37,625	32,161
OTHER LIABILITIES
Deferred revenue, non-current	10,625	10,847
Deferred rent, non-current	3,498	4,179
Deferred income tax liability, non-current	2,100	1,911
Total liabilities	53,848	49,098
COMMITMENTS and CONTINGENCIES
STOCKHOLDERS’ EQUITY
Preferred stock, $0.001 par value; 5,000,000 shares authorized; 0 shares issued and outstanding
Common stock, $0.001 par value; 55,000,000 shares authorized; 17,224,060 and 17,081,145 shares issued and outstanding, respectively	17	17
Additional paid-in capital	294,943	286,315
Accumulated deficit	(10,800)	(33,739)
Accumulated other comprehensive income (loss)	1,013	(3,326)
Total stockholders’ equity	285,173	249,267
Total liabilities and stockholders’ equity	$ 339,021	$ 298,365

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Allowance for doubtful accounts	$ 878	$ 515
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	55,000,000	55,000,000
Common stock, shares issued	17,224,060	17,081,145
Common stock, shares outstanding	17,224,060	17,081,145

Condensed Consolidated Statemen

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Revenues	$ 56,150	$ 49,284	$ 162,366	$ 142,234
Cost of revenues	18,645	16,171	54,166	47,024
Gross profit	37,505	33,113	108,200	95,210
Operating expenses
Sales and marketing	18,239	16,526	54,059	49,092
Research and development	6,549	5,574	17,023	16,185
General and administrative	8,744	7,149	24,709	21,516
Amortization of intangible assets	1,128	1,194	3,460	3,553
Total operating expenses	34,660	30,443	99,251	90,346
Income from operations	2,845	2,670	8,949	4,864
Other income (expense)
Interest income, net	272	112	704	408
Other income (expense), net	(195)	947	(356)	866
Total other income (expense), net	77	1,059	348	1,274
Income before income taxes	2,922	3,729	9,297	6,138
Income tax expense	(1,058)	(1,220)	(2,636)	(2,233)
Net income	$ 1,864	$ 2,509	$ 6,661	$ 3,905
Net income per share
Basic	$ 0.11	$ 0.15	$ 0.39	$ 0.23
Diluted	$ 0.11	$ 0.14	$ 0.38	$ 0.23
Weighted average common shares used to compute net income per share
Basic	17,223	17,001	17,192	16,916
Diluted	17,410	17,341	17,394	17,185
Other comprehensive income (loss)
Foreign currency translation adjustments	$ 1,779	$ 443	$ 4,291	$ 2,408
Unrealized gain (loss) on investments (net of tax of $10, ($50), $0, $12)	17	(80)		20
Reclassification of unrealized gain on investments into earnings (net of tax of $44, $14, $29, $13)	72	22	48	21
Comprehensive income	$ 3,732	$ 2,894	$ 11,000	$ 6,354

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Tax on net unrealized gain (loss) on investment securities available for sale	$ 10	$ (50)	$ 0	$ 12
Reclassification of unrealized gain on investments into earnings, tax	$ 44	$ 14	$ 29	$ 13

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities
Net income	$ 6,661	$ 3,905
Reconciliation of net income to net cash provided by operating activities
Deferred income taxes	1,968	(818)
Share-based earn-out liability		(1,103)
Depreciation and amortization of property and equipment	5,261	4,883
Amortization of intangible assets	3,460	3,553
Provision for doubtful accounts	1,365	977
Stock-based compensation	6,833	6,004
Other, net	(19)
Changes in assets and liabilities
Accounts receivable	(4,476)	(3,879)
Deferred costs	(4,487)	(4,194)
Other current and non-current assets	1,135	(2,840)
Accounts payable	632	(90)
Accrued compensation	(1,140)	173
Accrued expenses	469	126
Deferred revenue	4,932	3,927
Deferred rent	(622)	(271)
Net cash provided by operating activities	21,972	10,353
Cash flows from investing activities
Purchases of property and equipment	(5,242)	(5,972)
Purchases of marketable securities	(29,819)	(18,137)
Maturities of marketable securities	23,029	12,500
Acquisitions of businesses and intangible assets, net of cash acquired	(500)	(18,062)
Net cash used in investing activities	(12,532)	(29,671)
Cash flows from financing activities
Net proceeds from exercise of options to purchase common stock	1,307	3,520
Excess tax benefits from exercise of options to purchase common stock		2,710
Net proceeds from employee stock purchase plan	1,011	786
Net cash provided by financing activities	2,318	7,016
Effect of foreign currency exchange rate changes	1,349	399
Net increase (decrease) in cash and cash equivalents	13,107	(11,903)
Cash and cash equivalents at beginning of period	115,877	121,538
Cash and cash equivalents at end of period	$ 128,984	$ 109,635

General

General	9 Months Ended
	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
General	NOTE A – General Business Description We are a leading provider of cloud-based supply chain management solutions, providing network-proven fulfillment, sourcing, and item assortment management solutions, along with comprehensive retail performance analytics to thousands of customers worldwide. We provide our solutions through the SPS Commerce platform, a cloud-based product suite that improves the way suppliers, retailers, distributors and logistics firms orchestrate the sourcing, set up of new vendors and items, and fulfillment of the products that customers buy from retailers and suppliers. We derive the majority of our revenues from thousands of monthly recurring subscriptions from businesses that utilize our solutions. Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the accounts of SPS Commerce, Inc. and its subsidiaries. All intercompany accounts and transactions have been eliminated in the condensed consolidated financial statements, which Use of Estimates Preparing financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates. Significant Accounting Policies During the nine months ended September 30, 2017, there were no material changes in our significant accounting policies. See Note A to the consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2016, as filed with the Securities and Exchange Commission on February 27, 2017, for additional information regarding our significant accounting policies. Recently Adopted Accounting Pronouncements In March 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting We adopted ASU 2016-09 during the nine months ended September 30, 2017. The impact to our consolidated balance sheet as of January 1, 2017 was a $16.3 million increase in deferred income tax assets, non-current and a corresponding $16.3 million decrease in accumulated deficit. This impact results from the cumulative-effect adjustment for previously unrecognized excess tax benefits using the modified retrospective method required by the new standard. We elected to adopt the changes in cash flow statement presentation prospectively to be consistent with the prospective transition for the treatment of excess tax benefits in the income statement. Accordingly, we no longer classify excess tax benefits as a financing activity subsequent to January 1, 2017. Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) In February 2016, the FASB issued ASU 2016-02, Leases

Financial Instruments

Financial Instruments	9 Months Ended
	Sep. 30, 2017
Investments Debt And Equity Securities [Abstract]
Financial Instruments	NOTE B – Financial Instruments We invest primarily in money market funds, highly liquid debt instruments of the U.S. government, and U.S. corporate debt securities. All highly liquid investments with original maturities of 90 days or less are classified as cash equivalents. All investments with original maturities greater than 90 days and remaining maturities less than one year from the balance sheet date are classified as short-term marketable securities. Investments with remaining maturities of more than one year from the balance sheet date are classified as marketable securities, non-current. Short-term marketable securities and marketable securities, non-current, are also classified as available-for-sale. We intend to hold marketable securities until maturity; however, we may sell these securities at any time for use in current operations or for other purposes. Consequently, we may or may not keep securities with stated holding periods to maturity. Our fixed-income investments are carried at fair value; and unrealized gains and losses on these investments are included in other comprehensive income in the condensed consolidated statements of comprehensive income. Realized gains or losses are included in other income (expense) in the condensed consolidated statements of comprehensive income. When a determination has been made that an other-than-temporary decline in fair value has occurred, the amount of the decline that is related to a credit loss is realized and is included in other income (expense), net in the condensed consolidated statements of comprehensive income. Cash equivalents and marketable securities, consisted of the following: September 30, 2017 Amortized Unrealized Fair Cost Gains (Losses) Value (Dollars in thousands) Cash equivalents: Money market funds $ 76,507 $ — $ 76,507 Marketable securities: Corporate bonds 15,033 (35 ) 14,998 Commercial paper 9,944 14 9,958 U.S. treasury securities 12,380 24 12,404 $ 113,864 $ 3 $ 113,867 Due within one year $ 111,376 Due within two years 2,491 Total $ 113,867 December 31, 2016 Amortized Unrealized Fair Cost Gains (Losses) Value (Dollars in thousands) Cash equivalents: Money market funds $ 75,375 $ — $ 75,375 Marketable securities: Corporate bonds 15,681 (96 ) 15,585 Commercial paper 4,977 10 4,987 U.S. treasury securities 7,489 10 7,499 U.S. agency obligations 2,497 3 2,500 $ 106,019 $ (73 ) $ 105,946 Due within one year $ 98,452 Due within two years 7,494 Total $ 105,946 We do not believe any of the unrealized losses represent an other-than-temporary impairment based on our valuation of available evidence as of September 30, 2017. We expect to receive the full principal and interest on all of these cash equivalents and marketable securities. Fair Value Measurements We measure certain financial assets at fair value on a recurring basis based on a fair value hierarchy that requires us to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. A financial instrument’s categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The three levels of inputs that may be used to measure fair value are: • Level 1 – quoted prices in active markets for identical assets or liabilities • Level 2 – observable inputs other than Level 1 prices, such as: (a) quoted prices for similar assets or liabilities, (b) quoted prices in markets with insufficient volume or infrequent transactions (less active markets), or (c) model-derived valuations in which all significant inputs are observable or can be derived principally from or corroborated by observable market data for substantially the full term of the assets or liabilities. • Level 3 – unobservable inputs to the valuation methodology that are significant to the measurement of fair value of assets or liabilities. Level 1 Measurements Our cash equivalents held in money market funds are measured at fair value using level 1 inputs. Level 2 Measurements Our available-for-sale U.S. treasury securities, U.S. agency obligations, commercial paper and corporate debt securities are measured at fair value using level 2 inputs. We obtain the fair values of our level 2 available-for-sale securities from a professional pricing service. The following table presents information about our financial assets that are measured at fair value on a recurring basis and indicates the fair value hierarchy of the valuation techniques utilized to determine such fair value: September 30, 2017 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: Cash equivalents: Money market funds $ 76,507 $ — $ — $ 76,507 Marketable securities: Corporate bonds — 14,998 — 14,998 Commercial paper — 9,958 — 9,958 U.S. treasury securities — 12,404 — 12,404 Total $ 76,507 $ 37,360 $ — $ 113,867 December 31, 2016 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: Cash equivalents: Money market funds $ 75,375 $ — $ — $ 75,375 Marketable securities: Corporate bonds — 15,585 — 15,585 Commercial paper — 4,987 — 4,987 U.S. treasury securities — 7,499 — 7,499 U.S. agency obligations — 2,500 — 2,500 Total $ 75,375 $ 30,571 $ — $ 105,946 We classify our cash equivalents and marketable securities within Level 1 or Level 2 because we use quoted market prices or alternative pricing sources and models utilizing market observable inputs to determine their fair value.

Goodwill and Intangible Assets,

Goodwill and Intangible Assets, net	9 Months Ended
	Sep. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets, net	NOTE C – Goodwill and Intangible Assets, net Changes in the carrying amount of goodwill for the nine months ended September 30, 2017 are as follows: 2017 (Dollars in thousands) Balances, January 1 $ 49,777 Goodwill acquired during the period — Foreign currency translation adjustments 2,006 Balances, September 30 $ 51,783 Intangible assets subject to amortization primarily include subscriber relationships, non-competition agreements and acquired technology and are amortized over their respective useful lives (ranging from 1 to 9 years). Information regarding intangible assets included on our consolidated balance sheets is as follows: September 30, 2017 Foreign Carrying Accumulated Currency Amount Amortization Translation Net (Dollars in thousands) Subscriber relationships $ 34,350 $ (18,603 ) $ 679 $ 16,426 Non-competition agreements 2,499 (2,015 ) 49 533 Technology and other 2,130 (1,436 ) 67 761 $ 38,979 $ (22,054 ) $ 795 $ 17,720 December 31, 2016 Foreign Carrying Accumulated Currency Amount Amortization Translation Net (Dollars in thousands) Subscriber relationships $ 33,736 $ (15,708 ) $ 295 $ 18,323 Non-competition agreements 2,234 (1,818 ) 17 433 Technology and other 2,089 (1,120 ) 63 1,032 $ 38,059 $ (18,646 ) $ 375 $ 19,788 Total amortization expense for intangible assets during the three months ended September 30, 2017 and 2016 was $1.1 million and $1.2 million, respectively. Total amortization expense for intangible assets during the nine months ended September 30, 2017 and 2016 was $3.5 million and $3.6 million, respectively. The estimated annual amortization expense related to intangible assets subject to amortization for the next five years is as follows: (Dollars in thousands) Remainder of 2017 $ 1,125 2018 4,035 2019 3,743 2020 3,375 2021 2,529 Thereafter 2,913 $ 17,720

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	NOTE D – Commitments and Contingencies Operating Leases At September 30, 2017, our future minimum payments under operating leases were as follows: (Dollars in thousands) Remainder of 2017 $ 897 2018 3,639 2019 3,678 2020 1,981 2021 1,077 Thereafter 1,173 $ 12,445

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	NOTE E – Stock-Based Compensation Our equity compensation plans provide for the grant of incentive and nonqualified stock options, as well as other stock-based awards including restricted stock and restricted stock units, to employees, non-employee directors and other consultants who provide services to us. Restricted stock awards result in the issuance of new shares when granted. For other stock-based awards, new shares are issued when the award is exercised, vested or released according to the terms of the agreement. In February 2017, 1,024,868 additional shares were reserved for future issuance under our 2010 Equity Incentive Plan. At September 30, 2017, there were approximately 4.5 million shares available for grant under approved equity compensation plans. We recorded stock-based compensation expense of $2.3 million and $6.8 million for the three and nine months ended September 30, 2017 and $2.0 million and $6.0 million for the three and nine months ended September 30 Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 Cost of revenues $ 494 $ 319 $ 1,414 $ 916 Operating expenses Sales and marketing 565 620 1,656 1,913 Research and development 241 143 698 422 General and administrative 1,047 930 3,065 2,753 Total stock-based compensation expense $ 2,347 $ 2,012 $ 6,833 $ 6,004 As of September 30, 2017, there was approximately $17.9 million of unrecognized stock-based compensation expense under our equity compensation plans, which is expected to be recognized on a straight-line basis over a weighted average period of 2.6 years. Stock Options Stock options generally vest over four years and have a contractual term of seven to ten years from the date of grant. Our stock option activity was as follows: Weighted Average Options Exercise Price (#) ($/share) Outstanding at December 31, 2016 1,016,012 $ 44.72 Granted 169,451 56.02 Exercised (62,854 ) 20.79 Forfeited (10,622 ) 56.12 Outstanding at September 30, 2017 1,111,987 47.69 Of the total outstanding options at September 30, 2017, 708,209 were exercisable with a weighted average exercise price of $43.91 per share. The total outstanding options had a weighted average remaining contractual life of 4.3 years. The weighted average grant date fair value of options granted during the first nine months of 2017 was $18.90 and this was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions: Volatility 37.4 % Dividend yield 0 % Life (in years) 4.5 Risk-free interest rate 1.85 % Performance Share Units and Restricted Stock Units and Awards In February 2017, our executive officers were granted performance share unit (“PSU”) awards with vesting contingent on successful attainment of pre-determined revenue targets over the course of a three-year performance period (fiscal years 2017 – 2019). During the three months ended March 31, 2017, we recognized expense of $169,000 for PSU awards; and during the three months ended June 30, 2017 we recognized a reversing benefit of $169,000 as the probability of attainment was decreased. We recognized no expense for PSU awards during the three months ended September 30, 2017. Restricted stock units vest over four years and, upon vesting, the holder is entitled to receive shares of our common stock. With restricted stock awards, shares of our common stock are issued when the award is granted and the restrictions lapse over one year. Activity for our performance share units and restricted stock units was as follows: Performance Share and Weighted Average Restricted Stock Units Grant Date Fair Value (#) ($/share) Outstanding at December 31, 2016 189,042 $ 54.14 Granted 207,738 55.74 Vested and common stock issued (64,818 ) 53.63 Forfeited (4,805 ) 54.55 Outstanding at September 30, 2017 327,157 55.25 The number of restricted stock units outstanding at September 30, 2017 included 30,907 units that have vested, but for which shares of common stock have not yet been issued pursuant to the terms of the agreement. Our restricted stock awards activity was as follows: Restricted Stock Weighted Average Awards Grant Date Fair Value (#) ($/share) Outstanding at December 31, 2016 1,524 $ 52.28 Restricted common stock issued 5,454 58.29 Restrictions lapsed (4,248 ) 56.13 Forfeited — — Outstanding at September 30, 2017 2,730 58.30 Employee Stock Purchase Plan Our employee stock purchase plan a llows participating employees to purchase shares of our common stock at a discount through payroll deductions. The plan is available to all employees subject to certain eligibility requirements. Participating employees may purchase common stock, on a voluntary after tax basis, at a price that is the lower of 85% of the fair market value of one share of common stock at the beginning or end of each stock purchase period. The plan consists of two six-month offering periods, beginning on January 1 and July 1 of each calendar year, respectively. A total of 1.0 million shares of common stock are reserved for issuance under the plan. For the offering period that began on January 1, 2017 and ended on June 30, 2017, we withheld approximately $1,021,000 from employees participating in the plan. On June 30, 2017, approximately $1,011,000 of these funds were used to purchase 18,655 shares on behalf of the employees participating in the plan. The remaining funds were refunded to employees pursuant to the requirements of the plan. For the offering period that began on July 1, 2017 and will end on December 31, 2017, we have withheld approximately $599,000 as of September 30, 2017 from employees participating in the plan. For the three and nine months ended September 30, 2017 The fair value was estimated based on the market price of our common stock at the beginning of the offering period using the Black-Scholes option pricing model with the following assumptions: Volatility 26.0 % Dividend yield 0 % Life (in years) 0.5 Risk-free interest rate 0.62 %

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	NOTE F – Income Taxes We record our interim provision for income taxes by applying our estimated annual effective tax rate to our year-to-date pretax income and adjust the provision for discrete tax items recorded in the period. Differences between our effective tax rate and statutory tax rates are primarily due to the impact of permanently non-deductible expenses partially offset by the federal research and development credit. Additionally, excess tax benefits generated upon settlement or exercise of stock awards are now recognized as a reduction to income tax expense as a discrete tax item in the quarter that the event occurs creating potentially significant fluctuation in tax expense by quarter and by year. Our provisions for income taxes include current foreign and state income tax expense, as well as deferred tax expense. As of September 30, 2017 we do not have any unrecognized tax benefits nor any accrued interest or tax penalties.

Net Income Per Share

Net Income Per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Net Income Per Share	NOTE G – Net Income Per Share Basic net income per share has been computed using the weighted average number of shares of common stock outstanding during each period. Diluted net income per share also includes the impact of our outstanding potential common shares, including options and restricted stock units. Potential common shares that are anti-dilutive are excluded from the calculation of diluted net income per share. The following table presents the components of the computation of basic and diluted net income per share for the periods indicated (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 Net income $ 1,864 $ 2,509 $ 6,661 $ 3,905 Net income per share Basic $ 0.11 $ 0.15 $ 0.39 $ 0.23 Diluted $ 0.11 $ 0.14 $ 0.38 $ 0.23 Weighted average common shares outstanding, basic 17,223 17,001 17,192 16,916 Options to purchase common stock 152 295 169 253 Restricted stock units 35 44 33 16 Employee stock purchase plan — 1 — — Weighted average common shares outstanding, diluted 17,410 17,341 17,394 17,185 Antidilutive shares 267 265 267 276

General (Policies)

General (Policies)	9 Months Ended
	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the accounts of SPS Commerce, Inc. and its subsidiaries. All intercompany accounts and transactions have been eliminated in the condensed consolidated financial statements, which
Use of Estimates	Use of Estimates Preparing financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates.
Significant Accounting Policies	Significant Accounting Policies During the nine months ended September 30, 2017, there were no material changes in our significant accounting policies. See Note A to the consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2016, as filed with the Securities and Exchange Commission on February 27, 2017, for additional information regarding our significant accounting policies.
Recently Adopted/Recent Accounting Pronouncements	Recently Adopted Accounting Pronouncements In March 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting We adopted ASU 2016-09 during the nine months ended September 30, 2017. The impact to our consolidated balance sheet as of January 1, 2017 was a $16.3 million increase in deferred income tax assets, non-current and a corresponding $16.3 million decrease in accumulated deficit. This impact results from the cumulative-effect adjustment for previously unrecognized excess tax benefits using the modified retrospective method required by the new standard. We elected to adopt the changes in cash flow statement presentation prospectively to be consistent with the prospective transition for the treatment of excess tax benefits in the income statement. Accordingly, we no longer classify excess tax benefits as a financing activity subsequent to January 1, 2017. Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) In February 2016, the FASB issued ASU 2016-02, Leases

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2017
Investments Debt And Equity Securities [Abstract]
Summary of Investment in Cash Equivalents and Marketable Securities	Cash equivalents and marketable securities, consisted of the following: September 30, 2017 Amortized Unrealized Fair Cost Gains (Losses) Value (Dollars in thousands) Cash equivalents: Money market funds $ 76,507 $ — $ 76,507 Marketable securities: Corporate bonds 15,033 (35 ) 14,998 Commercial paper 9,944 14 9,958 U.S. treasury securities 12,380 24 12,404 $ 113,864 $ 3 $ 113,867 Due within one year $ 111,376 Due within two years 2,491 Total $ 113,867 December 31, 2016 Amortized Unrealized Fair Cost Gains (Losses) Value (Dollars in thousands) Cash equivalents: Money market funds $ 75,375 $ — $ 75,375 Marketable securities: Corporate bonds 15,681 (96 ) 15,585 Commercial paper 4,977 10 4,987 U.S. treasury securities 7,489 10 7,499 U.S. agency obligations 2,497 3 2,500 $ 106,019 $ (73 ) $ 105,946 Due within one year $ 98,452 Due within two years 7,494 Total $ 105,946
Summary of Financial Assets Measured at Fair Value on a Recurring Basis	The following table presents information about our financial assets that are measured at fair value on a recurring basis and indicates the fair value hierarchy of the valuation techniques utilized to determine such fair value: September 30, 2017 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: Cash equivalents: Money market funds $ 76,507 $ — $ — $ 76,507 Marketable securities: Corporate bonds — 14,998 — 14,998 Commercial paper — 9,958 — 9,958 U.S. treasury securities — 12,404 — 12,404 Total $ 76,507 $ 37,360 $ — $ 113,867 December 31, 2016 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: Cash equivalents: Money market funds $ 75,375 $ — $ — $ 75,375 Marketable securities: Corporate bonds — 15,585 — 15,585 Commercial paper — 4,987 — 4,987 U.S. treasury securities — 7,499 — 7,499 U.S. agency obligations — 2,500 — 2,500 Total $ 75,375 $ 30,571 $ — $ 105,946

Goodwill and Intangible Asset16

Goodwill and Intangible Assets, net (Tables)	9 Months Ended
	Sep. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Changes in Carrying Amount of Goodwill	Changes in the carrying amount of goodwill for the nine months ended September 30, 2017 are as follows: 2017 (Dollars in thousands) Balances, January 1 $ 49,777 Goodwill acquired during the period — Foreign currency translation adjustments 2,006 Balances, September 30 $ 51,783
Intangible Assets Subject to Amortization	Intangible assets subject to amortization primarily include subscriber relationships, non-competition agreements and acquired technology and are amortized over their respective useful lives (ranging from 1 to 9 years). Information regarding intangible assets included on our consolidated balance sheets is as follows: September 30, 2017 Foreign Carrying Accumulated Currency Amount Amortization Translation Net (Dollars in thousands) Subscriber relationships $ 34,350 $ (18,603 ) $ 679 $ 16,426 Non-competition agreements 2,499 (2,015 ) 49 533 Technology and other 2,130 (1,436 ) 67 761 $ 38,979 $ (22,054 ) $ 795 $ 17,720 December 31, 2016 Foreign Carrying Accumulated Currency Amount Amortization Translation Net (Dollars in thousands) Subscriber relationships $ 33,736 $ (15,708 ) $ 295 $ 18,323 Non-competition agreements 2,234 (1,818 ) 17 433 Technology and other 2,089 (1,120 ) 63 1,032 $ 38,059 $ (18,646 ) $ 375 $ 19,788
Estimated Annual Amortization Expense Related to Intangible Assets Subject to Amortization	The estimated annual amortization expense related to intangible assets subject to amortization for the next five years is as follows: (Dollars in thousands) Remainder of 2017 $ 1,125 2018 4,035 2019 3,743 2020 3,375 2021 2,529 Thereafter 2,913 $ 17,720

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Future Minimum Payments Under Operating Leases	At September 30, 2017, our future minimum payments under operating leases were as follows: (Dollars in thousands) Remainder of 2017 $ 897 2018 3,639 2019 3,678 2020 1,981 2021 1,077 Thereafter 1,173 $ 12,445

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2017
Stock-Based Compensation Expense	This expense was allocated in the consolidated statements of comprehensive income as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 Cost of revenues $ 494 $ 319 $ 1,414 $ 916 Operating expenses Sales and marketing 565 620 1,656 1,913 Research and development 241 143 698 422 General and administrative 1,047 930 3,065 2,753 Total stock-based compensation expense $ 2,347 $ 2,012 $ 6,833 $ 6,004
Stock Option Activity	Our stock option activity was as follows: Weighted Average Options Exercise Price (#) ($/share) Outstanding at December 31, 2016 1,016,012 $ 44.72 Granted 169,451 56.02 Exercised (62,854 ) 20.79 Forfeited (10,622 ) 56.12 Outstanding at September 30, 2017 1,111,987 47.69
Weighted Average Grant Date Fair Value of Options Granted, Assumptions	The weighted average grant date fair value of options granted during the first nine months of 2017 was $18.90 and this was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions: Volatility 37.4 % Dividend yield 0 % Life (in years) 4.5 Risk-free interest rate 1.85 %
Fair Value Estimation of Common Stock Using Black-Scholes Option Pricing Model, Assumptions	The fair value was estimated based on the market price of our common stock at the beginning of the offering period using the Black-Scholes option pricing model with the following assumptions: Volatility 26.0 % Dividend yield 0 % Life (in years) 0.5 Risk-free interest rate 0.62 %
Performance Share Units and Restricted Stock Units [Member]
Performance Share Units and Restricted Stock Units and Restricted Stock Awards	Activity for our performance share units and restricted stock units was as follows: Performance Share and Weighted Average Restricted Stock Units Grant Date Fair Value (#) ($/share) Outstanding at December 31, 2016 189,042 $ 54.14 Granted 207,738 55.74 Vested and common stock issued (64,818 ) 53.63 Forfeited (4,805 ) 54.55 Outstanding at September 30, 2017 327,157 55.25
Restricted Stock Award [Member]
Performance Share Units and Restricted Stock Units and Restricted Stock Awards	Our restricted stock awards activity was as follows: Restricted Stock Weighted Average Awards Grant Date Fair Value (#) ($/share) Outstanding at December 31, 2016 1,524 $ 52.28 Restricted common stock issued 5,454 58.29 Restrictions lapsed (4,248 ) 56.13 Forfeited — — Outstanding at September 30, 2017 2,730 58.30

Net Income Per Share (Tables)

Net Income Per Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Components of Computation of Basic and Diluted Net Income Per Share	The following table presents the components of the computation of basic and diluted net income per share for the periods indicated (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 Net income $ 1,864 $ 2,509 $ 6,661 $ 3,905 Net income per share Basic $ 0.11 $ 0.15 $ 0.39 $ 0.23 Diluted $ 0.11 $ 0.14 $ 0.38 $ 0.23 Weighted average common shares outstanding, basic 17,223 17,001 17,192 16,916 Options to purchase common stock 152 295 169 253 Restricted stock units 35 44 33 16 Employee stock purchase plan — 1 — — Weighted average common shares outstanding, diluted 17,410 17,341 17,394 17,185 Antidilutive shares 267 265 267 276

General - Additional Informatio

General - Additional Information (Detail) - ASU 2016-09 [Member] $ in Millions	Jan. 01, 2017USD ($)
Deferred Income Tax Assets, Non-Current [Member]
Schedule Of Accounting Policies [Line Items]
Cumulative effect of change due to new accounting pronouncement	$ 16.3
Accumulated Deficit [Member]
Schedule Of Accounting Policies [Line Items]
Cumulative effect of change due to new accounting pronouncement	$ 16.3

Financial Instruments - Summary

Financial Instruments - Summary of Investment in Cash Equivalents and Marketable Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Cash Equivalents and Marketable Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Due within one year	$ 111,376	$ 98,452
Amortized Cost	113,864	106,019
Due within two years	2,491	7,494
Unrealized Gains (Losses)	3	(73)
Fair Value	113,867	105,946
Money Market Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	76,507	75,375
Fair Value	76,507	75,375
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	15,033	15,681
Unrealized Gains (Losses)	(35)	(96)
Fair Value	14,998	15,585
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,944	4,977
Unrealized Gains (Losses)	14	10
Fair Value	9,958	4,987
U.S. Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12,380	7,489
Unrealized Gains (Losses)	24	10
Fair Value	$ 12,404	7,499
U.S. Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		2,497
Unrealized Gains (Losses)		3
Fair Value		$ 2,500

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail)	Sep. 30, 2017USD ($)
Money Market Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Losses	$ 0

Financial Instruments - Summa23

Financial Instruments - Summary of Financial Assets Measured at Fair Value on a Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets fair value	$ 113,867	$ 105,946
Money Market Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets fair value	76,507	75,375
Corporate Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets fair value	14,998	15,585
Commercial Paper [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets fair value	9,958	4,987
U.S. Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets fair value	12,404	7,499
U.S. Agency Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets fair value		2,500
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets fair value	76,507	75,375
Level 1 [Member] | Money Market Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets fair value	76,507	75,375
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets fair value	37,360	30,571
Level 2 [Member] | Corporate Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets fair value	14,998	15,585
Level 2 [Member] | Commercial Paper [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets fair value	9,958	4,987
Level 2 [Member] | U.S. Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets fair value	$ 12,404	7,499
Level 2 [Member] | U.S. Agency Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets fair value		$ 2,500

Goodwill and Intangible Asset24

Goodwill and Intangible Assets, net - Schedule of Changes in Carrying Amount of Goodwill (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
Balances, January 1	$ 49,777
Goodwill acquired during the period	0
Foreign currency translation adjustments	2,006
Balances, September 30	$ 51,783

Goodwill and Intangible Asset25

Goodwill and Intangible Assets, net - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 1,128	$ 1,194	$ 3,460	$ 3,553
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets useful life			1 year
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets useful life			9 years

Goodwill and Intangible Asset26

Goodwill and Intangible Assets, net - Intangible Assets Subject to Amortization (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Carrying Amount	$ 38,979	$ 38,059
Accumulated Amortization	(22,054)	(18,646)
Foreign Currency Translation	795	375
Net	17,720	19,788
Subscriber Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Carrying Amount	34,350	33,736
Accumulated Amortization	(18,603)	(15,708)
Foreign Currency Translation	679	295
Net	16,426	18,323
Non-competition Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Carrying Amount	2,499	2,234
Accumulated Amortization	(2,015)	(1,818)
Foreign Currency Translation	49	17
Net	533	433
Technology and Other [Member]
Finite-Lived Intangible Assets [Line Items]
Carrying Amount	2,130	2,089
Accumulated Amortization	(1,436)	(1,120)
Foreign Currency Translation	67	63
Net	$ 761	$ 1,032

Goodwill and Intangible Asset27

Goodwill and Intangible Assets, net - Estimated Annual Amortization Expense Related to Intangible Assets Subject to Amortization (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Remainder of 2017	$ 1,125
2,018	4,035
2,019	3,743
2,020	3,375
2,021	2,529
Thereafter	2,913
Net	$ 17,720	$ 19,788

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Payments Under Operating Leases (Detail) $ in Thousands	Sep. 30, 2017USD ($)
Commitments And Contingencies Disclosure [Abstract]
Remainder of 2017	$ 897
2,018	3,639
2,019	3,678
2,020	1,981
2,021	1,077
Thereafter	1,173
Operating leases, total	$ 12,445

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail)	Jun. 30, 2017USD ($)shares	Feb. 28, 2017shares	Sep. 30, 2017USD ($)$ / sharesshares	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)OfferingPeriod$ / sharesshares	Sep. 30, 2016USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant | shares			4,500,000				4,500,000
Stock-based compensation expense			$ 2,347,000			$ 2,012,000	$ 6,833,000	$ 6,004,000
Unrecognized stock-based compensation expense			$ 17,900,000				$ 17,900,000
Unrecognized stock-based compensation, expected to be recognized, weighted average period							2 years 7 months 7 days
Stock options exercisable | shares			708,209				708,209
Weighted average exercise price | $ / shares			$ 43.91				$ 43.91
Weighted average remaining contractual life							4 years 3 months 19 days
Weighted average fair value per share of options granted | $ / shares							$ 18.90
Number of offerings per year | OfferingPeriod							2
Net proceeds from employee stock purchase plan							$ 1,011,000	$ 786,000
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			$ 152,000				$ 444,000
Percentage of common stock on fair market value							85.00%
Common stock reserved for future issuance | shares			1,000,000				1,000,000
Employee stock purchase plan, employees contribution	$ 1,021,000		$ 599,000	$ 1,021,000			$ 599,000
Net proceeds from employee stock purchase plan	$ 1,011,000
Employee stock purchase plan, shares purchased | shares	18,655
Equity Incentive Plan [Member] | 2010 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares were authorized under 2010 Equity Incentive Plan | shares		1,024,868
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options vest, period							4 years
Stock options contractual term, from the date of grant							seven to ten years
Stock Options [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options contractual term range							7 years
Stock Options [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options contractual term range							10 years
Performance Share Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			$ 0		$ 169,000
Stock options vest, period		3 years
Stock-based compensation reversing benefit				$ 169,000
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options vest, period							4 years
Number of RSU's vested and not issued during the period | shares							30,907
Restricted Stock Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards units vest over, period							1 year

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 2,347	$ 2,012	$ 6,833	$ 6,004
Cost of Revenues [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	494	319	1,414	916
Sales and Marketing [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	565	620	1,656	1,913
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	241	143	698	422
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 1,047	$ 930	$ 3,065	$ 2,753

Stock-Based Compensation - St31

Stock-Based Compensation - Stock Option Activity (Detail)	9 Months Ended
	Sep. 30, 2017$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options Outstanding, Beginning balance | shares	1,016,012
Options, Granted | shares	169,451
Options, Exercised | shares	(62,854)
Options, Forfeited | shares	(10,622)
Options Outstanding, Ending balance | shares	1,111,987
Weighted Average Exercise Price, Outstanding, Beginning Balance | $ / shares	$ 44.72
Weighted Average Exercise Price, Granted | $ / shares	56.02
Weighted Average Exercise Price, Exercised | $ / shares	20.79
Weighted Average Exercise Price, Forfeited | $ / shares	56.12
Weighted Average Exercise Price, Outstanding, Ending Balance | $ / shares	$ 47.69

Stock-Based Compensation - Weig

Stock-Based Compensation - Weighted Average Grant Date Fair Value of Options Granted, Assumptions (Detail) - Stock Options [Member]	9 Months Ended
	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility	37.40%
Dividend yield	0.00%
Life (in years)	4 years 6 months
Risk-free interest rate	1.85%

Stock-Based Compensation - Perf

Stock-Based Compensation - Performance Share Units and Restricted Stock Units (Detail) - Performance Share Units and Restricted Stock Units [Member]	9 Months Ended
	Sep. 30, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards, Outstanding, Beginning Balance | shares	189,042
Granted, stock units | shares	207,738
Vested, stock units | shares	(64,818)
Forfeited, stock units | shares	(4,805)
Stock awards, Outstanding, Ending Balance | shares	327,157
Weighted average grant date fair value, Outstanding, Beginning Balance | $ / shares	$ 54.14
Granted, Weighted Average Grant Date Fair Value | $ / shares	55.74
Vested, Weighted Average Grant Date Fair Value | $ / shares	53.63
Forfeited, Weighted Average Grant Date Fair Value | $ / shares	54.55
Weighted average grant date fair value, Outstanding, Ending Balance | $ / shares	$ 55.25

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Awards (Detail) - Restricted Stock Award [Member]	9 Months Ended
	Sep. 30, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards, Outstanding, Beginning Balance | shares	1,524
Restricted common stock issued, stock awards | shares	5,454
Restrictions lapsed, stock awards | shares	(4,248)
Forfeited, stock awards | shares	0
Stock awards, Outstanding, Ending Balance | shares	2,730
Weighted average grant date fair value, Outstanding, Beginning Balance | $ / shares	$ 52.28
Restricted common stock issued, Weighted Average Grant Date Fair Value | $ / shares	58.29
Restrictions lapsed, Weighted Average Grant Date Fair Value | $ / shares	56.13
Forfeited, Weighted Average Grant Date Fair Value | $ / shares	0
Weighted average grant date fair value, Outstanding, Ending Balance | $ / shares	$ 58.30

Stock-Based Compensation - Fair

Stock-Based Compensation - Fair Value Estimation of Common Stock Using Black-Scholes Option Pricing Model, Assumptions (Detail) - Employee Stock Purchase Plan [Member]	9 Months Ended
	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility	26.00%
Dividend yield	0.00%
Life (in years)	6 months
Risk-free interest rate	0.62%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail)	Sep. 30, 2017USD ($)
Income Tax Disclosure [Abstract]
Unrecognized tax benefits	$ 0
Accrued interest or tax penalties	$ 0

Net Income Per Share - Componen

Net Income Per Share - Components of Computation of Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Net income	$ 1,864	$ 2,509	$ 6,661	$ 3,905
Net income per share
Basic	$ 0.11	$ 0.15	$ 0.39	$ 0.23
Diluted	$ 0.11	$ 0.14	$ 0.38	$ 0.23
Weighted average common shares outstanding, basic	17,223	17,001	17,192	16,916
Options to purchase common stock	152	295	169	253
Restricted stock units	35	44	33	16
Employee stock purchase plan		1
Weighted average common shares outstanding, diluted	17,410	17,341	17,394	17,185
Antidilutive shares	267	265	267	276