Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Numerator:
Net income - basic									$ 32,952	$ 28,145
Net income - diluted									$ 32,952	$ 28,145
Denominator:
Weighted average shares outstanding - basic (in shares)									7,281,136	7,322,158
Weighted average shares outstanding - diluted (in shares)									7,299,720	7,345,045
Earnings per common share:
Basic (in dollars per share)	$ 1.18	$ 1.12	$ 1.13	$ 1.10	$ 0.99	$ 0.99	$ 0.94	$ 0.92	$ 4.53	$ 3.84
Diluted (in dollars per share)	$ 1.17	$ 1.12	$ 1.13	$ 1.10	$ 0.99	$ 0.99	$ 0.93	$ 0.92	$ 4.51	$ 3.83
Plus: Effect of Director Compensation Program
Denominator:
Plus: Effect of dilutive securities (in shares)									923	1,259
Plus: Effect of stock options and restricted stock
Denominator:
Plus: Effect of dilutive securities (in shares)									17,661	21,628