CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance (in shares) at Dec. 31, 2014		7,426,222
Beginning Balance at Dec. 31, 2014	$ 245,109	$ 41,555	$ 211,979	$ (8,425)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	12,804		12,804
Other comprehensive income, net of tax	737			737
Stock-based compensation expense	410	$ 410
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit (shares)		23,423
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit	375	$ 375
Stock Repurchased During Period, Shares		0
Stock Repurchased During Period, Value	421	$ (421)
Cash dividends declared ($0.60 and $0.60 per share in six months ended June 30, 2015 and June 30, 2016)	(4,474)		(4,474)
Ending Balance (in shares) at Jun. 30, 2015		7,449,645
Ending Balance at Jun. 30, 2015	254,540	$ 41,919	220,309	(7,688)
Beginning Balance (in shares) at Dec. 31, 2015		10,220,478
Beginning Balance at Dec. 31, 2015	363,190	$ 153,083	222,329	(12,222)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	18,262		18,262
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income		72	(72)
Other comprehensive income, net of tax	8,214			8,214
Stock-based compensation expense	1,042	$ 1,042
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit (shares)		60,635
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit	377	$ 377
Cash dividends declared ($0.60 and $0.60 per share in six months ended June 30, 2015 and June 30, 2016)	(6,229)		(6,229)
Ending Balance (in shares) at Jun. 30, 2016		10,281,113.000
Ending Balance at Jun. 30, 2016	$ 384,856	$ 154,574	$ 234,290	$ (4,008)