Company Net Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
NOL carryforwards	$ 170,200	$ 162,248	$ 134,023
Research and development credits	12,721	12,721	11,357
Deferred revenue	1,451	302	7,224
Other temporary differences	5,935	11,135	15,158
Valuation allowance	(190,307)	(186,406)	(167,762)
Total	$ 0	$ 0	$ 0