Earnings (Loss) Per Share - Schedule of Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic:
Net income (loss), basic	$ 3,998	$ (16,694)	$ (17,662)	$ 21,647
Net income (loss), shares, basic	302,154	262,586	299,212	262,044
Net income (loss), per share, basic	$ 0.01	$ (0.06)	$ (0.06)	$ 0.08
Weighted-average number of shares of common stock-diluted:
Restricted stock and performance unit awards	395			2,673
Diluted:
Net income (loss), diluted	$ 3,998	$ (16,694)	$ (17,662)	$ 21,647
Net income (loss), shares, diluted	302,548	262,586	299,212	264,717
Net income (loss), per share, diluted	$ 0.01	$ (0.06)	$ (0.06)	$ 0.08