Net Loss Per Share - 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
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Net loss	$ (53,787)	$ (52,676)
Weighted average shares outstanding – basic and diluted (in shares)	190,304	187,837
Net loss per share – basic and diluted (in usd per share)	$ (0.28)	$ (0.28)