CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance (in shares) at Dec. 31, 2019		15,144,719
Beginning Balance at Dec. 31, 2019	$ 473,415	$ 139,103	$ 340,580	$ (6,268)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	41,208		41,208
Other comprehensive income, net of tax	25,843			25,843
Stock-based compensation expense	1,373	$ 1,373
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit (shares)		37,571
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings	(113)	$ (113)
Common stock repurchased (in shares)		(264,946)
Common stock repurchased	(9,375)	$ (9,375)
Cash dividends declared	(14,829)		(14,829)
Ending Balance (in shares) at Sep. 30, 2020		14,917,344
Ending Balance at Sep. 30, 2020	517,522	$ 130,988	366,959	19,575
Beginning Balance (in shares) at Jun. 30, 2020		14,963,041
Beginning Balance at Jun. 30, 2020	506,467	$ 131,981	355,130	19,356
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	16,775		16,775
Other comprehensive income, net of tax	219			219
Stock-based compensation expense	422	$ 422
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit (shares)		2,218
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings	(13)	$ (13)
Common stock repurchased (in shares)		(47,915)
Common stock repurchased	(1,402)	$ (1,402)
Cash dividends declared	(4,946)		(4,946)
Ending Balance (in shares) at Sep. 30, 2020		14,917,344
Ending Balance at Sep. 30, 2020	517,522	$ 130,988	366,959	19,575
Beginning Balance (in shares) at Dec. 31, 2020		14,909,097
Beginning Balance at Dec. 31, 2020	529,314	$ 131,072	377,502	20,740
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	52,523		52,523
Other comprehensive income, net of tax	(16,573)			(16,573)
Stock-based compensation expense	2,007	$ 2,007
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit (shares)		46,732
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings	(241)	$ (241)
Common stock repurchased (in shares)		(106,502)
Common stock repurchased	(4,913)	$ (4,913)
Cash dividends declared	(16,133)		(16,133)
Ending Balance (in shares) at Sep. 30, 2021		14,849,327
Ending Balance at Sep. 30, 2021	545,984	$ 127,925	413,892	4,167
Beginning Balance (in shares) at Jun. 30, 2021		14,951,067
Beginning Balance at Jun. 30, 2021	545,548	$ 132,278	404,602	8,668
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	14,640		14,640
Other comprehensive income, net of tax	(4,501)			(4,501)
Stock-based compensation expense	493	$ 493
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit (shares)		4,762
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings	67	$ 67
Common stock repurchased (in shares)		(106,502)
Common stock repurchased	(4,913)	$ (4,913)
Cash dividends declared	(5,350)		(5,350)
Ending Balance (in shares) at Sep. 30, 2021		14,849,327
Ending Balance at Sep. 30, 2021	$ 545,984	$ 127,925	$ 413,892	$ 4,167