Calculation of Net Income (Loss) and Number of Shares Used to Compute Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Net loss	$ (55,451)	$ (50,108)	$ (171,285)	$ (156,851)
Net loss per share - basic and diluted	$ (0.29)	$ (0.27)	$ (0.91)	$ (0.84)
Weighted average shares outstanding - basic and diluted	188,921	187,034	188,456	186,703