Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Net income available to common shareholders	$ 19,814	$ 29,000
Less: earnings allocated to participating securities	(179)	(263)
Net earnings allocated to common shareholders	19,635	28,737
Distributed earnings allocated to common stock	9,037	9,117
Undistributed earnings allocated to common stock	$ 10,598	$ 19,620
Average shares outstanding (in shares)	15,656	16,080
Effect of dilutive securities:
Employee stock awards (in shares)	31	21
Average common shares outstanding, diluted (in shares)	15,687	16,101
Basic earnings per common share (in dollars per share)	$ 1.25	$ 1.79
Diluted earnings per share (in dollars per share)	$ 1.25	$ 1.78