Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Loss before provision for income taxes:
Domestic	$ (57,513)	$ (46,908)	$ (37,481)
Foreign	(10,858)	(8,524)	(9,851)
Loss before provision (benefit) for income taxes	(68,371)	(55,432)	(47,332)
Current tax provision:
Federal	1	1
State	24	15	10
Foreign	353	164	83
Total current tax provision	378	180	93
Deferred Income Tax Expense (Benefit)
Federal		(286)
State		(45)
Foreign	330	(326)	(65)
Total deferred tax expense (benefit)	330	(657)	(65)
Total provision (benefit) for income taxes	$ 708	$ (477)	$ 28
Items accounting for the difference between income taxes computed at the federal statutory rate and the provision for income taxes
Federal statutory rate (as a percent)	34.00%	34.00%	34.00%
Stock-based compensation (as a percent)	(1.15%)	(0.74%)	(1.59%)
Valuation allowance (as a percent)	(36.51%)	(34.38%)	(28.31%)
Foreign rate differential (as a percent)	(3.11%)	(2.52%)	(5.00%)
Federal research and development credit (as a percent)	3.28%	2.48%	1.19%
Other (as a percent)	2.42%	2.03%	(0.35%)
Effective income tax rate (as a percent)	(1.06%)	0.87%	(0.06%)
Deferred tax assets:
Accounts receivable principally due to allowance for doubtful accounts	$ 166	$ 130	$ 92
Compensated absences, principally due to accruals for financial reporting purposes	2,880	1,867	2,993
Net operating loss carryforwards	69,369	54,949	42,704
Federal tax credits	3,657	2,437	1,766
State tax credits net of federal benefit	2,010	1,521	1,166
Other deductible temporary differences	2,234	1,311	964
Stock-based compensation	12,106	7,289	1,508
Foreign Credit	22	24	25
Total deferred tax assets	92,444	69,528	51,218
Deferred tax liabilities:
Capitalized software development	(566)	(278)	(149)
Acquired intangible assets	(1,208)	(1,983)	(1,979)
Total deferred tax liability	(1,774)	(2,261)	(2,128)
Valuation allowance	(90,892)	(67,159)	(49,388)
Net deferred taxes	(222)	108	(298)
Deferred Tax Assets, Net of Valuation Allowance	(222)	108	$ (298)
Increase in net valuation allowance	$ 23,700	$ 17,800