Earnings (Loss) per Common Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings (loss) per common share—basic
Net income (loss)	$ (5,866)	$ (3,617)	$ 66,629	$ 45,020
Weighted-average common shares outstanding—basic (in shares)	94,081	83,875	94,021	80,030
Basic earnings per common share (in dollars per share)	$ (0.06)	$ (0.04)	$ 0.71	$ 0.56
Earnings (loss) per common share—diluted
Interest on convertible debt	$ 0	$ 0	$ 0	$ 5,329
Net income (loss) including assumed conversions	$ (5,866)	$ (3,617)	$ 66,629	$ 50,349
Weighted-average common shares outstanding—basic (in shares)	94,081	83,875	94,021	80,030
Convertible notes weighted-average shares outstanding (in shares)	0	0	0	13,217
Options and restricted stock (in shares)	0	0	1,666	1,367
Weighted-average common shares outstanding—diluted (in shares)	94,081	83,875	95,687	94,614
Dilutive earnings (loss) per common share (in dollars per share)	$ (0.06)	$ (0.04)	$ 0.70	$ 0.53