Earnings (Loss) Per Share - Schedule of Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Basic:
Net income (loss), basic	$ (19,036)	$ 11,494	$ (21,660)	$ 38,341
Net income (loss), shares, basic	301,936	262,423	297,717	261,768
Net income (loss), per share, basic	$ (0.06)	$ 0.04	$ (0.07)	$ 0.15
Weighted-average number of shares of common stock-diluted:
Restricted stock and performance unit awards		1,997		2,553
Diluted:
Net income (loss), diluted	$ (19,036)	$ 11,494	$ (21,660)	$ 38,341
Net income (loss), shares, diluted	301,936	264,420	297,717	264,321
Net income (loss), per share, diluted	$ (0.06)	$ 0.04	$ (0.07)	$ 0.15