Difference Between Provision for Income Taxes and Amounts Computed by Applying Federal Statutory Income Tax Rate to Loss before Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Provision of Income Taxes [Line Items]
Federal statutory tax	$ (20,243)	$ (13,110)	$ (14,661)
Warrants	(3,565)	(3,367)	4,926
Expiration of federal loss carryovers	3,337
Change in valuation allowance	11,754	16,576	9,955
Change in state apportionment	4,085
Other	961	96	(2)
(Benefit) provision for income taxes	$ (3,671)	$ 195	$ 218