Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2017	22,679
Balance, January 1, 2018 at Dec. 31, 2017	$ 36,457	$ 31,924	$ 267,193	$ (1,930)	$ 333,644
Net income			13,404		13,404
Net change in accumulated other comprehensive loss				(3,408)	(3,408)
Reclassification adjustment under Accounting Standards Update 2018-02			506	(506)
Stock compensation expense		823			823
Stock issued for share-based awards, net of withholdings to satisfy employee tax obligations upon award (in shares)	52
Stock issued for share-based awards, net of withholdings to satisfy employee tax obligations upon award	$ 174	205	(1,914)		(1,535)
Cash dividends declared			(5,226)		(5,226)
Shares cancelled (in shares)	(1)
Shares cancelled	$ (4)	(35)	39
Balance (in shares) at Mar. 31, 2018	22,730
Balance, March 31, 2018 at Mar. 31, 2018	$ 36,627	32,917	274,002	(5,844)	337,702
Balance (in shares) at Dec. 31, 2018	22,749
Balance, January 1, 2018 at Dec. 31, 2018	$ 36,689	36,797	298,156	(5,142)	366,500
Net income			15,641		15,641
Net change in accumulated other comprehensive loss				2,629	2,629
Stock compensation expense		863			863
Stock issued for share-based awards, net of withholdings to satisfy employee tax obligations upon award (in shares)	74
Stock issued for share-based awards, net of withholdings to satisfy employee tax obligations upon award	$ 245	2,254	(4,452)		(1,953)
Cash dividends declared			(5,686)		(5,686)
Balance (in shares) at Mar. 31, 2019	22,823
Balance, March 31, 2018 at Mar. 31, 2019	$ 36,934	$ 39,914	$ 303,659	$ (2,513)	$ 377,994