Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Treasury Stock [Member]
Beginning balance at Dec. 31, 2015	$ 361,574	$ 110,271	$ 121,280	$ 193,446	$ (16,708)	$ (46,715)
Beginning balance, shares at Dec. 31, 2015		19,530,930
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	7,289	$ 0	0	7,289	0	0
Other comprehensive income, net of income tax	1,227	0	0	0	1,227	0
Cash dividends declared ($0.20 per share)	(3,908)	0	0	(3,908)	0	0
Stock issued under dividend reinvestment and employee stock purchase plans	617	$ 0	8	0	0	609
Stock issued under dividend reinvestment and employee stock purchase plans, shares		30,121
Exercise of stock options	274	$ 0	9	0	0	265
Exercise of stock options, shares		14,167
Repurchase of cancelled restricted stock awards	0	$ 0	241	0	0	(241)
Repurchase of cancelled restricted stock awards, shares		(14,250)
Stock-based compensation	451	$ 0	451	0	0	0
Purchases of treasury stock	(521)	$ 0	0	0	0	(521)
Purchases of treasury stock, shares		(26,750)
Restricted stock awards granted	0	$ 0	(1,083)	0	0	1,083
Restricted stock awards granted, shares		58,580
Ending balance at Mar. 31, 2016	367,003	$ 110,271	120,906	196,827	(15,481)	(45,520)
Ending balance, shares at Mar. 31, 2016		19,592,798
Beginning balance at Dec. 31, 2016	505,209	$ 144,559	230,494	194,516	(19,454)	(44,906)
Beginning balance, shares at Dec. 31, 2016		26,589,353
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	10,856	$ 0	0	10,856	0	0
Other comprehensive income, net of income tax	462	0	0	0	462	0
Cash dividends declared ($0.20 per share)	(5,322)	0	0	(5,322)	0	0
Stock issued under dividend reinvestment and employee stock purchase plans	617	$ 0	16	0	0	601
Stock issued under dividend reinvestment and employee stock purchase plans, shares		20,944
Exercise of stock options	$ 861	$ 0	(62)	0	0	923
Exercise of stock options, shares	47,704	47,704
Repurchase of cancelled restricted stock awards	$ 0	$ 0	246	0	0	(246)
Repurchase of cancelled restricted stock awards, shares		(13,125)
Stock-based compensation	831	$ 0	831	0	0	0
Purchases of treasury stock	(1,634)	$ 0	0	0	0	(1,634)
Purchases of treasury stock, shares		(57,804)
Restricted stock awards granted	0	$ 0	(1,134)	0	0	1,134
Restricted stock awards granted, shares		58,448
Ending balance at Mar. 31, 2017	$ 511,880	$ 144,559	$ 230,391	$ 200,050	$ (18,992)	$ (44,128)
Ending balance, shares at Mar. 31, 2017		26,645,520