Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Shares to be Issued for Deferred Compensation Obligations	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balances at Dec. 31, 2016	$ 187,899	$ 139,525	$ 5,038	$ 46,114	$ (2,778)
Beginning balances, shares at Dec. 31, 2016		7,821,069
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	13,780			13,237	543
Reclassification resulting from the enactment of the Tax Act	0			367	(367)
Issuance of common stock	6,177	$ 6,177
Issuance of common stock, shares		220,510
Common stock transferred from the Rabbi Trust to satisfy deferred compensation obligations	0	$ 176	(176)
Share based payment awards under equity compensation plan	640		640
Common stock purchased for deferred compensation obligations	(420)	(420)
Common stock repurchased pursuant to publicly announced repurchase plan	(5,181)	$ (5,181)
Common stock repurchased pursuant to publicly announced repurchase plan, shares		(184,286)
Cash dividends	(7,990)			(7,990)
Ending balances at Dec. 31, 2017	194,905	$ 140,277	5,502	51,728	(2,602)
Ending balances, shares at Dec. 31, 2017		7,857,293
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	8,715			14,021	(5,306)
Issuance of common stock	6,864	$ 6,864
Issuance of common stock, shares		261,693
Common stock transferred from the Rabbi Trust to satisfy deferred compensation obligations	0	$ 683	(683)
Share based payment awards under equity compensation plan	612		612
Common stock purchased for deferred compensation obligations	(401)	(401)
Common stock repurchased pursuant to publicly announced repurchase plan	(7,007)	$ (7,007)
Common stock repurchased pursuant to publicly announced repurchase plan, shares		(248,017)
Cash dividends	(8,169)			(8,169)
Ending balances at Dec. 31, 2018	$ 195,519	$ 140,416	5,431	57,357	(7,685)
Ending balances, shares at Dec. 31, 2018	7,870,969	7,870,969
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 0			(223)	223
Comprehensive income (loss)	22,680			13,024	9,656
Issuance of common stock	4,876	$ 4,876
Issuance of common stock, shares		209,583
Common stock transferred from the Rabbi Trust to satisfy deferred compensation obligations	0	$ 911	(911)
Share based payment awards under equity compensation plan	523		523
Common stock purchased for deferred compensation obligations	(1,131)	(1,131)
Common stock repurchased pursuant to publicly announced repurchase plan	(4,003)	$ (4,003)
Common stock repurchased pursuant to publicly announced repurchase plan, shares		(169,748)
Cash dividends	(8,282)			(8,282)
Ending balances at Dec. 31, 2019	$ 210,182	$ 141,069	$ 5,043	$ 62,099	$ 1,971
Ending balances, shares at Dec. 31, 2019	7,910,804	7,910,804