Income Taxes - Income Tax Provision Related to Continuing Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
U.S. federal provision (benefit)
At statutory rate	$ (28,235)	$ (19,050)	$ (55,919)
State taxes	(1)	1	50
Change in valuation allowance	22,210	11,831	55,042
Non-cash interest expense on liability related to sale of future royalties	7,217	7,311	7,808
Stock-based compensation	674	2,832	271
Foreign tax inclusion	1,773	0	0
Foreign tax differential	(7)	(17)	(20)
Research credits	(4,529)	(2,933)	(6,273)
Other	1,404	(487)	1,286
Provision (benefit) for income taxes	$ 506	$ (512)	$ 2,245