Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 15,537	$ 13,164	$ 15,035	$ (11,163)	$ 16,384	$ 16,360	$ 15,785	$ 10,677	$ 32,573	$ 59,206	$ 63,792
Denominator for basic earnings per share – Weighted average shares outstanding (in shares)									19,970,921	20,142,306	20,234,792
Effect of dilutive potential common shares (in shares)									71,424	91,065	155,375
Adjusted weighted-average diluted shares (in shares)									20,042,345	20,233,371	20,390,167
Basic earnings per share (in dollars per share)	$ 0.78	$ 0.66	$ 0.75	$ (0.56)	$ 0.81	$ 0.81	$ 0.78	$ 0.53	$ 1.63	$ 2.94	$ 3.15
Diluted earnings per share (in dollars per share)	$ 0.78	$ 0.66	$ 0.75	$ (0.56)	$ 0.81	$ 0.81	$ 0.78	$ 0.53	$ 1.63	$ 2.93	$ 3.13
Antidilutive shares excluded from computation of average dilutive earnings per share (in shares)									34,792	3,671	19,422