Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net Income	$ 44,734	$ 50,727	$ 95,944	$ 148,322
Earnings allocated to participating securities - nonvested restricted shares	164	358	487	1,204
Earnings allocated to common shareholders, Basic	$ 44,570	$ 50,369	$ 95,457	$ 147,118
Weighted average common shares outstanding	70,726	71,803	70,870	72,256
Basic earnings per common share	$ 0.63	$ 0.70	$ 1.35	$ 2.04
Earnings allocated to common shareholders, Diluted	$ 44,570	$ 50,369	$ 95,457	$ 147,118
Dilutive effect of equity awards	36	0	36	1
Weighted average diluted common shares outstanding	70,762	71,803	70,906	72,257
Diluted earnings per common share	$ 0.63	$ 0.70	$ 1.35	$ 2.04
Potentially dilutive share options that were not included in the computation of diluted EPS because to do so would be anti-dilutive.	596	0	487	0