Net Income (or Loss) and Number of Shares Used to Compute Basic and Diluted Earnings per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Loss Per Share [Line Items]
Net loss-basic	$ (26,050)	$ (48,884)	$ (36,707)	$ (150,816)
Gain on warrant derivative liability	(4,392)		(6,773)	(15,256)
Net loss-diluted	$ (30,442)	$ (48,884)	$ (43,480)	$ (166,072)
Net loss per share-basic	$ (0.15)	$ (0.29)	$ (0.21)	$ (0.96)
Weighted average shares outstanding-basic	174,502	170,187	173,426	157,105
Effect of dilutive warrants	639		879	6,382
Weighted average shares outstanding-diluted	175,141	170,187	174,305	163,487
Net loss per share-diluted	$ (0.17)	$ (0.29)	$ (0.25)	$ (1.02)