Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) Customer	Dec. 31, 2015 USD ($) Customer	Dec. 31, 2014 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Cash equivalent consist of money market with maturity dates	90 days	90 days
Cash equivalents	$ 15,657	$ 25,564
Allowance for potential customer credits	1,947	2,274
Capitalization of internally developed software costs	4,712	5,568	$ 3,146
Amortization of internally developed software	2,988	2,550	1,905
Unamortized internally developed software costs	$ 10,218	8,495
Goodwill impairment, assessment of fair value of reporting unit description	During the fourth quarter of 2016, the market capitalization of the Company’s publicly traded common stock sustained a decline to the extent that it fell below the book value of the Company’s net assets for a period of time before subsequently increasing and rising back above the book value of the net assets. Management considered the possible factors affecting the assessment of the fair value of the Company’s reporting unit for the purposes performing the goodwill impairment assessment, including those listed above.
Goodwill impairment	$ 0	0	0
Impairment losses on long-lived assets	0	0	0
Advertising and promotion expense	876	1,000	1,475
Gains losses from foreign exchange transactions	(3)	$ 256	$ (490)
Additional tax expense	$ 0
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible assets amortized useful lives	2 years
Minimum [Member] | Subscription arrangement [Member]
Summary Of Significant Accounting Policies [Line Items]
Length of subscription agreements	1 year
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible assets amortized useful lives	6 years
Software [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of internally developed software	3 years
Concentration of Credit Risk [Member] | Accounts Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of customers accounted for greater than 10% | Customer	0	0
Concentration of Credit Risk [Member] | Revenues [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of customers accounted for greater than 10% | Customer	0	0