Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Net operating loss carryforwards	$ 508,406	$ 447,761
Research and other credits	74,917	70,258
Stock-based compensation	26,357	22,832
Deferred revenue	23,035	29,658
Reserves and accruals	12,269	8,309
Capitalized research expenses	11,587	12,440
Property, plant and equipment	6,882	6,451
Sale of future royalties	1,611	12,319
Other	750	3,158
Deferred tax assets before valuation allowance	665,814	613,186
Valuation allowance for deferred tax assets	(665,514)	(612,996)
Total deferred tax assets	300	190
Total deferred tax liabilities	0	0
Net deferred tax assets	$ 300	$ 190