Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net Income	$ 55,039	$ 36,582	$ 106,892	$ 51,210
Earnings allocated to participating securities - nonvested restricted shares	70	139	227	325
Earnings allocated to common shareholders, Basic	$ 54,969	$ 36,443	$ 106,665	$ 50,885
Weighted average common shares outstanding	70,987	70,679	70,924	70,942
Basic earnings per common share	$ 0.77	$ 0.52	$ 1.50	$ 0.72
Earnings allocated to common shareholders, Diluted	$ 54,969	$ 36,443	$ 106,665	$ 50,885
Dilutive effect of equity awards	177	32	155	39
Weighted average diluted common shares outstanding	71,164	70,711	71,079	70,981
Diluted earnings per common share	$ 0.77	$ 0.52	$ 1.50	$ 0.72
Potentially dilutive stock awards and units that were not included in the computation of diluted EPS because to do so would be anti-dilutive.	248	571	158	450