Basic and Diluted Net Loss per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013		Jun. 30, 2014	Jun. 30, 2013
Components Of Basic And Diluted Earning Per Share [Line Items]
Net (loss) income	$ (9,187)	$ 1,697		$ (16,486)	$ 1,737
Less: Earnings allocated to participating securities		(1,697)	[1]		(1,737)	[1]
Net loss available to common shareholders after required adjustments for the calculation of basic and diluted earnings per common share	$ (9,187)			$ (16,486)
Basic weighted average common shares outstanding	28,985,590	25,117,624		28,451,564	24,471,528
Weighted average effect of dilutive securities:
Stock Options		11,750,364			12,574,948
Warrants		831,900			862,168
Diluted weighted average common shares outstanding	28,985,590	37,699,888		28,451,564	37,908,644
Loss per common share
Basic	$ (0.32)			$ (0.58)
Diluted	$ (0.32)			$ (0.58)

[1] In a period with net income, both earnings and dividends (if any) are allocated to participating securities. In a period with a net loss, only dividends (if any) are allocated to participating securities.