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 Income (Loss) [Member]
Common stock, shares outstanding, beginning balance at Dec. 31, 2013		16,614,000
Stockholders' equity, beginning balance at Dec. 31, 2013	$ 329,646	$ 1,038	$ 97,566	$ 232,595	$ (1,553)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	40,824			40,824
Total other comprehensive income (loss), net of tax	(7,256)				(7,256)
Cash dividends declared	(20,582)			(20,582)
Share-based compensation	1,880		1,880
Common stock issued for acquisition	0
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit, shares		132,000
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit	1,767	$ 9	1,758
Common stock, shares outstanding, ending balance at Dec. 31, 2014		16,746,000
Stockholders' equity, ending balance at Dec. 31, 2014	346,279	$ 1,047	101,204	252,837	(8,809)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	43,465			43,465
Total other comprehensive income (loss), net of tax	(890)				(890)
Cash dividends declared	(23,228)			(23,228)
Share-based compensation	2,074		2,074
Common stock issued for acquisition, shares		137,000
Common stock issued for acquisition	5,430	$ 8	5,422
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit, shares		137,000
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit	$ 2,258	$ 9	2,249
Common stock, shares outstanding, ending balance at Dec. 31, 2015	17,019,578	17,020,000
Stockholders' equity, ending balance at Dec. 31, 2015	$ 375,388	$ 1,064	110,949	273,074	(9,699)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	46,481			46,481
Total other comprehensive income (loss), net of tax	(10,058)				(10,058)
Cash dividends declared	(25,190)			(25,190)
Share-based compensation	2,190		2,190
Common stock issued for acquisition	0
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit, shares		151,000
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit	$ 1,993	$ 9	1,984
Common stock, shares outstanding, ending balance at Dec. 31, 2016	17,170,820	17,171,000
Stockholders' equity, ending balance at Dec. 31, 2016	$ 390,804	$ 1,073	$ 115,123	$ 294,365	$ (19,757)