Summary of Significant Accounting Policies - Basic and Diluted Net Loss Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Numerator
Net loss for basic EPS	$ 62,865	$ (13,332)	$ 41,933	$ (34,389)
Common stock warrants	0	0	18,470	0
Net loss for diluted EPS	$ 62,865	$ (13,332)	$ 23,463	$ (34,389)
Denominator
Weighted average common shares outstanding, basic	139,985	100,876	139,635	100,843
Common stock warrants, shares	0	0	3,137	0
Weighted average common shares outstanding, diluted	139,985	100,876	142,772	100,843
Basic net loss per share, usd per share	$ 0.45	$ (0.13)	$ 0.30	$ (0.34)
Diluted net loss per share, usd per share	$ 0.45	$ (0.13)	$ 0.16	$ (0.34)