CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) - 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
Shareholders' Equity, Beginning Balance at Dec. 31, 2013	$ 329,646	$ 1,038	$ 97,566	$ 232,595	$ (1,553)
Net income	29,633			29,633
Total other comprehensive income (loss), net of tax	1,974				1,974
Cash dividends declared	(15,176)			(15,176)
Share-based compensation	1,433		1,433
Common stock issued for acquisition	0
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit, shares		107,000
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit	1,052	$ 7	1,045
Common Stock, Shares Outstanding, Ending Balance at Sep. 30, 2014		16,721,000
Shareholders' Equity, Ending Balance at Sep. 30, 2014	$ 348,562	$ 1,045	100,044	247,052	421
Common Stock, Shares Outstanding, Beginning Balance at Dec. 31, 2014	16,746,363	16,746,000
Shareholders' Equity, Beginning Balance at Dec. 31, 2014	$ 346,279	$ 1,047	101,204	252,837	(8,809)
Net income	32,721			32,721
Total other comprehensive income (loss), net of tax	384				384
Cash dividends declared	(17,392)			(17,392)
Share-based compensation	1,640		1,640
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		102,000
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit	$ 1,465	$ 7	1,458
Common Stock, Shares Outstanding, Ending Balance at Sep. 30, 2015	16,984,737	16,985,000
Shareholders' Equity, Ending Balance at Sep. 30, 2015	$ 370,527	$ 1,062	$ 109,724	$ 268,166	$ (8,425)