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		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Net loss	$ (50,108)	$ (66,339)	$ (156,851)	$ (199,995)
Net loss per share - basic and diluted	$ (0.27)	$ (0.36)	$ (0.84)	$ (1.09)
Weighted average shares - basic and diluted	187,034	185,238	186,703	182,859