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			11,139,333
Beginning Balance at Dec. 31, 2014		$ 245,109	$ 41,555	$ 211,979	$ (8,425)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		19,260		19,260
Other comprehensive income, net of tax		2,074			2,074
Stock-based compensation expense		542	$ 542
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit (shares)			41,734
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit		512	$ 512
Stock Repurchased During Period, Shares			0
Stock Repurchased During Period, Value		537	$ (537)
Cash dividends declared ($0.60 and $0.60 per share in nine months ended September 30, 2015 and September 30, 2016)	[1]	(7,557)		(7,557)
Ending Balance (in shares) at Sep. 30, 2015			11,181,067
Ending Balance at Sep. 30, 2015		259,403	$ 42,072	223,682	(6,351)
Beginning Balance (in shares) at Dec. 31, 2015			15,330,717
Beginning Balance at Dec. 31, 2015		363,190	$ 153,083	222,329	(12,222)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		29,165		29,165
Cumulative effect adjustment			$ 72	(72)
Cash in-lieu, Shares, Stock Splits			(173)
Cash in-lieu, stock split		(5)	$ (5)
Other comprehensive income, net of tax		8,047			8,047
Stock-based compensation expense		1,521	$ 1,521
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit (shares)			104,312
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit		593	$ 593
Cash dividends declared ($0.60 and $0.60 per share in nine months ended September 30, 2015 and September 30, 2016)	[1]	(9,330)		(9,330)
Ending Balance (in shares) at Sep. 30, 2016			15,434,856.000
Ending Balance at Sep. 30, 2016		$ 393,181	$ 155,264	$ 242,092	$ (4,175)

[1] (1) Share and per share amounts have been adjusted to reflect the three-for-two stock split effective September 30, 2016, for all periods presented. Refer to Note 2.