Reconciliation of Numerator and Denominator Used in Computation of Basic and Diluted Net Income Loss 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
Numerator for Basic and Diluted:
Net loss used for basic calculation	$ (10,759)	$ (20,501)	$ (18,573)	$ (37,477)
Effect of revaluation of warrant liability	(1,738)	0	(14,263)	0
Adjusted net loss used for diluted calculation	$ (12,497)	$ (20,501)	$ (32,836)	$ (37,477)
Denominator:
Basic weighted average number of shares outstanding	75,194	69,791	73,407	66,464
Effect of dilutive potential shares	909	0	2,030	0
Diluted weighted average number of shares outstanding	76,103	69,791	75,437	66,464
Net loss per share:
Basic	$ (0.14)	$ (0.29)	$ (0.25)	$ (0.56)
Diluted	$ (0.16)	$ (0.29)	$ (0.44)	$ (0.56)