Earnings Per Common Share - Computation of basic and diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Basic earnings per common share:
Net income	$ 122,788	$ 95,221	$ 368,697	$ 34,396
Weighted-average basic common shares	70,066	70,905	70,643	49,330
Basic earnings per common share (in dollars per share)	$ 1.75	$ 1.34	$ 5.22	$ 0.70
Diluted earnings per common share:
Net income	$ 122,788	$ 95,221	$ 368,697	$ 34,396
Weighted-average basic common shares	70,066	70,905	70,643	49,330
Effect of dilutive securities (in shares)	510	171	465	306
Weighted-average dilutive shares	70,576	71,076	71,108	49,636
Diluted earnings per common share (in dollars per share)	$ 1.74	$ 1.34	$ 5.19	$ 0.69