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
	Mar. 31, 2017	Mar. 31, 2016
Earnings per common share—basic
Net income	$ 25,689	$ 38,390
Weighted-average common shares outstanding—basic (in shares)	94,070	93,952
Basic earnings per common share (in dollars per share)	$ 0.27	$ 0.41
Earnings per common share—diluted
Weighted-average common shares outstanding—basic (in shares)	94,070	93,952
Options and restricted stock (in shares)	1,878	1,472
Weighted-average common shares outstanding—diluted (in shares)	95,948	95,424
Dilutive earnings (loss) per common share (in dollars per share)	$ 0.27	$ 0.40