Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock,Voting	Common Stock,Nonvoting	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance at Dec. 31, 2016	$ 139,207	$ 878	$ 11,205		$ 116,143	$ 17,132	$ (6,151)
Beginning balance, shares at Dec. 31, 2016			11,204,515
Issuance of restricted common stock, net of forfeitures and withholdings to satisfy employee tax obligations	(264)		$ 21		(285)
Issuance of restricted common stock, net of forfeitures and withholdings to satisfy employee tax obligations, shares			21,480
Stock-based compensation expense	771				771
Excess tax benefit from stock compensation	644		$ 72		572
Excess tax benefit from stock compensation, shares			71,517
Exercise of common stock warrants	465		$ 49		416
Exercise of common stock warrants, shares			48,986
Net income	1,409					1,409
Other comprehensive income (loss)	1,972						1,972
Ending balance at Sep. 30, 2017	144,204	878	$ 11,347		117,617	18,541	(4,179)
Ending balance, shares at Sep. 30, 2017			11,346,498
Beginning balance at Dec. 31, 2017	146,946	878	$ 11,450	$ 133	118,120	18,892	(2,527)
Beginning balance, shares at Dec. 31, 2017			11,449,465	132,561
Issuance of restricted common stock, net of forfeitures and withholdings to satisfy employee tax obligations	(420)		$ 23		(443)
Issuance of restricted common stock, net of forfeitures and withholdings to satisfy employee tax obligations, shares			23,195
Stock-based compensation expense	940				940
Exercise of employee common stock options	$ 1,943		$ 334		1,609
Exercise of employee common stock options, shares	508,834		333,726
Exercise of common stock warrants	$ 1,606		$ 186		1,420
Exercise of common stock warrants, shares			186,175
Common and preferred stock dividends declared	(514)					(514)
Net income	10,363					10,363
Other comprehensive income (loss)	(3,354)						(3,354)
Ending balance at Sep. 30, 2018	$ 157,510	$ 878	$ 11,993	$ 133	$ 121,646	$ 28,741	$ (5,881)
Ending balance, shares at Sep. 30, 2018			11,992,561	132,561