Earnings Per Common Share - Computation of basic and diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Basic earnings per common share:
Net income	$ 24,110	$ 44,367
Weighted-average basic common shares	33,566	35,445
Basic earnings per common share (in dollars per share)	$ 0.72	$ 1.25
Diluted earnings per share:
Net income	$ 24,110	$ 44,367
Weighted-average basic common shares	33,566	35,445
Effect of dilutive securities (in shares)	239	174
Weighted-average dilutive shares	33,805	35,619
Diluted earnings per common share (in dollars per share)	$ 0.71	$ 1.25