Income Taxes - Report of Company's Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Federal and state net operating loss carryforwards	$ 139,874	$ 130,011
Federal and state research and development credit carryforwards	16,222	15,536
Accrued liabilities	3,460	7,177
Properties and Equipment	7,740	0
Capitalized research and development costs	16,263	16,027
Other	1,842	2,092
Total deferred tax assets	185,401	170,843
Valuation allowance	(185,401)	(170,843)
Net deferred tax assets	$ 0	$ 0