Calculation of Net Income (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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Net loss	$ (56,921)	$ (68,985)	$ (106,743)	$ (133,655)
Net loss per share - basic and diluted	$ (0.30)	$ (0.37)	$ (0.57)	$ (0.74)
Weighted average shares - basic and diluted	186,815	184,726	186,535	181,651