Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance at Dec. 31, 2015	$ 8,698	$ 171,353	$ (7,937)	$ 172,114
Net income		14,942		14,942
Other comprehensive income (loss), net of tax			(722)	(722)
Cash dividend		(8,071)		(8,071)
Balance at Dec. 31, 2016	8,698	178,224	(8,659)	178,263
Net income		14,092		14,092
Other comprehensive income (loss), net of tax			682	682
Cash dividend		(8,141)		(8,141)
Reclassification of stranded tax effects from change in tax rate		1,718	(1,718)
Balance at Dec. 31, 2017	8,698	185,893	(9,695)	184,896
Net income		16,151		16,151
Other comprehensive income (loss), net of tax			(2,390)	(2,390)
Cash dividend		(8,419)		(8,419)
Balance at Dec. 31, 2018	$ 8,698	$ 193,625	$ (12,085)	$ 190,238