CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) (USD $) In Thousands, except Share data	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Shareholders' Equity, Beginning Balance at Dec. 31, 2013	$ 329,646	$ 1,038	$ 97,566	$ 232,595	$ (1,553)
Common Stock, Shares Outstanding, Beginning Balance at Dec. 31, 2013		16,614,000
Net income	9,298			9,298
Total other comprehensive income, net of tax	776				776
Cash dividends declared	(4,894)			(4,894)
Share-based compensation	491		491
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit, shares		21,000
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit	541	2	539
Shareholders' Equity, Ending Balance at Mar. 31, 2014	335,858	1,040	98,596	236,999	(777)
Common Stock, Shares Outstanding, Ending Balance at Mar. 31, 2014		16,635,000
Shareholders' Equity, Beginning Balance at Dec. 31, 2014	346,279	1,047	101,204	252,837	(8,809)
Common Stock, Shares Outstanding, Beginning Balance at Dec. 31, 2014	16,746,363	16,746,000
Net income	11,010			11,010
Total other comprehensive income, net of tax	984				984
Cash dividends declared	(5,778)			(5,778)
Share-based compensation	580		580
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit, shares		27,000
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit	804	1	803
Shareholders' Equity, Ending Balance at Mar. 31, 2015	$ 353,879	$ 1,048	$ 102,587	$ 258,069	$ (7,825)
Common Stock, Shares Outstanding, Ending Balance at Mar. 31, 2015	16,772,956	16,773,000