Basic and Diluted Net 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
Earnings Per Share [Abstract]
Net loss	$ (29,226)		$ (42,030)		$ (91,373)		$ (103,165)
Weighted-average number of shares of common stock and common stock equivalents outstanding:
Weighted-average number of common stock outstanding for computing basic net loss per share	41,066		33,943		39,595		32,588
Dilutive effect of outstanding warrants and stock awards after application of the treasury stock method		[1]		[1]		[1]		[1]
Weighted-average number of common stock outstanding for computing diluted net loss per share	41,066		33,943		39,595		32,588
Net loss per share - basic and diluted	$ (0.71)		$ (1.24)		$ (2.31)		$ (3.17)

[1] For the three and nine months ended September 30, 2014 and 2013, stock options, restricted stock awards, restricted stock units and stock appreciation rights to purchase approximately 5,305,219 and 5,293,145 shares of common stock were excluded from the net loss per share calculation, respectively, as their effect would have been anti-dilutive.