Income Taxes - Schedule of Temporary Differences That Give Rise to Significant Net Deferred Tax Assets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Deferred tax assets
Net operating losses	$ 113,843	$ 77,806
Capitalized research and development expenses	32,771	40,083
Credit carryforwards	37,304	14,398
Depreciation	2,735	2,931
Deferred compensation	8,249	5,068
Accrued expenses	841	1,184
Deferred revenues	28,381	29,936
Other temporary differences	5,885	1,934
Total gross deferred tax asset	230,009	173,340
Valuation allowance	(207,304)	(169,651)	(132,683)	(103,881)
Net deferred tax asset	22,705	3,689
Deferred tax liabilities
Intangible assets	(3,234)	(3,689)
Debt discount	(19,471)
Net deferred taxes