Income Taxes - Reconciliation of Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets:
Net operating loss carryforwards	$ 4,306	$ 2,647
Deferred revenue	3,739	2,421
Accrued expenses	2,549	1,357
Deferred rent	1,119	322
Credit carryforwards	14,871	2,342
Facility exit obligation	698	1,102
Stock-based compensation	15,464	7,474
Note Hedge and other	48,241	0
Other	1,448	1,367
Total deferred tax assets	92,435	19,032
Less valuation allowance	(25,795)	(13,270)
Deferred tax assets net	66,640	5,762
Deferred tax liabilities:
Depreciation	(9,608)	(5,016)
Deferred Tax Liabilities, Financing Arrangements	(54,817)	0
Deferred Tax Liabilities, Goodwill and Intangible Assets	(1,239)	0
Net deferred tax assets	$ 976	$ 746