Income Taxes - Income Tax Provision Related to Continuing Operations (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
U.S. federal provision (benefit)
At statutory rate	$ (19,050)	$ (55,919)	$ (60,007)
State taxes	1	50	(48)
Change in valuation allowance	11,831	55,042	47,349
Non-cash interest expense on liability related to sale of future royalties	7,311	7,808	6,320
Stock-based compensation	2,832	271	236
Foreign tax inclusion			6,510
Foreign tax differential	(17)	(20)	(227)
Research credits	(2,933)	(6,273)	(591)
Other	(487)	1,286	864
(Benefit) provision for income taxes	$ (512)us-gaap_IncomeTaxExpenseBenefit	$ 2,245us-gaap_IncomeTaxExpenseBenefit	$ 406us-gaap_IncomeTaxExpenseBenefit

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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