Earnings Per Share - Reconciliation Of Numerators And Denominators (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic EPS:
Net income	$ 81,477	$ 92,046	$ 89,289
Less: income allocated to participating securities	(398)	(450)	0
Basic EPS per common share	$ 81,079	$ 91,596	$ 89,289
Basic (in shares)	28,839,866	29,547,851	29,566,259
Basic (in dollars per share)	$ 2.81	$ 3.10	$ 3.02
Diluted EPS:
Net income	$ 81,477	$ 92,046	$ 89,289
Effect of Dilutive Securities	0	0	0
Diluted EPS per common share	$ 81,477	$ 92,046	$ 89,289
Basic (in shares)	28,839,866	29,547,851	29,566,259
Effect of Dilutive Securities (in shares)	141,701	172,648	141,172
Diluted (in shares)	28,981,567	29,720,499	29,707,431
Diluted (in dollars per share)	$ 2.81	$ 3.10	$ 3.01