Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]
Balance, shares at Dec. 31, 2016	20,969,000
Balance, shares at Mar. 31, 2017	20,969,000
Balance at Dec. 31, 2016	$ 210,214	$ 210	$ 153,353	$ 53,640	$ 3,011
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	161		161
Dividends	(1,258)			(1,258)
Other comprehensive income (loss), net of tax	1,073				1,073
Net income	6,281			6,281
Balance at Mar. 31, 2017	$ 216,471	210	153,514	58,663	4,084
Balance, shares (Previously Reported [Member]) at Dec. 31, 2017	21,036,000
Balance, shares at Dec. 31, 2017	21,036,087
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation (shares)	36,000
Balance, shares at Mar. 31, 2018	21,072,152
Balance (Previously Reported [Member]) at Dec. 31, 2017	$ 238,189	210	155,082	73,502	9,395
Balance at Dec. 31, 2017	238,189	210	155,082	79,992	2,905
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of tax effects resulting from the TCJA	0			(1,308)	1,308
Issuance of common stock under stock-based compensation plan	545		545
Stock-based compensation	158		158
Dividends	(1,473)			(1,473)
Other comprehensive income (loss), net of tax	(4,856)				(4,856)
Net income	7,287			7,287
Balance at Mar. 31, 2018	239,850	$ 210	$ 155,785	84,498	(643)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment - net unrealized gains on equity securities	$ 0			$ 6,490	$ (6,490)