Income Taxes - Company's Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets:
Net operating loss carryforwards	$ 21,901	$ 1,666
Deferred revenue	23,171	33,250
Tax credit carryforwards	637	427
Purchased intangible assets	147	158
Stock-based compensation	768	269
Deferred rent	138	172
Other	231	232
Total deferred tax assets	46,993	36,174
Valuation allowance	(46,549)	(31,786)	(10,700)
Total deferred tax assets	444	4,388
Deferred tax liabilities:
Depreciation and amortization	(444)	(435)
Total deferred tax liabilities	(444)	(435)
Net deferred tax asset		$ 3,953