Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012 security	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012 security	Dec. 31, 2011
Significant Accounting Policies [Line Items]
Withdrawn secondary offering expense									$ 0	$ 0	$ 555,000
Accounting for Commission Payments
Commissions deferred during the period									22,800,000	16,100,000	7,700,000
Deferred commissions	16,634,000				9,354,000				16,634,000	9,354,000
Research and development	5,893,000	5,716,000	5,232,000	4,419,000	4,261,000	4,101,000	3,431,000	3,093,000	21,260,000	14,886,000	10,149,000
Advertising expense									2,000,000	400,000	300,000
Stock Based Compensation - Black-Scholes Option-Pricing Model Assumptions:
Risk-free interest rate									1.50%	1.00%	1.70%
Expected term									6 years 0 months 11 days	5 years 10 months 2 days	6 years
Estimated dividend yield									0.00%	0.00%	0.00%
Estimated volatility									51.50%	53.90%	56.90%
Capitalized Software Costs
Capitalized software costs, estimated useful life									3 years
Capitalized software costs, amount capitalized during the period									7,900,000	5,700,000	3,300,000
Amortization of capitalized software costs									4,300,000	2,800,000	1,900,000
Capitalized software costs, estimated amortization expense in 2014	5,000,000								5,000,000
Capitalized software costs, estimated amortization expense in 2015	3,700,000								3,700,000
Capitalized software costs, estimated amortization expense in 2016	1,800,000								1,800,000
Capitalized software costs, estimated amortization expense in 2017	200,000								200,000
Cash and Cash Equivalents
Cash balances	43,900,000				24,900,000				43,900,000	24,900,000
Money market funds backed by U.S. Treasury Bills	65,700,000				51,500,000				65,700,000	51,500,000
Short-term investments	199,925,000				0				199,925,000	0
Number of available-for-sale securities					0					0
Restricted cash	200,000				100,000				200,000	100,000
Allowance for Doubtful Accounts - Reconciliation:
Beginning balance, January 1				464,000				153,000	464,000	153,000	32,000
Additions and adjustments									968,000	358,000	203,000
Write-offs									(411,000)	(47,000)	(82,000)
Ending balance, December 31	1,021,000				464,000				1,021,000	464,000	153,000
Impairment of Long Lived Assets
Impairment charges related to identified intangible assets									0	0
Intangible Assets
Accretion of preferred stock											5,200,000
Minimum
Accounting for Commission Payments
Commission payment period		45 days
Intangible Assets
Identified intangible assets amortization period									2 years
Maximum
Accounting for Commission Payments
Commission payment period		75 days
Intangible Assets
Identified intangible assets amortization period									10 years
General and administrative
Significant Accounting Policies [Line Items]
Acquisition related costs									0	700,000
Sales and marketing
Accounting for Commission Payments
Amortization of deferred commissions									15,500,000	10,300,000	6,500,000
Other income (expense), net
Intangible Assets
Foreign currency transactions and translation									$ (300,000)	$ 200,000	$ (500,000)
Revenue | Customer concentration risk
Intangible Assets
Number of major customers									0	0	0
Concentration Risk, Percentage									10.00%	10.00%	10.00%
Accounts receivable | Customer concentration risk
Intangible Assets
Number of major customers									0	0
Concentration Risk, Percentage									10.00%	10.00%