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]
Stockholders' Equity, Beginning Balance at Dec. 31, 2012	$ 295,652	$ 1,024	$ 91,453	$ 213,674	$ (10,499)
Common Stock, Shares Outstanding, Beginning Balance at Dec. 31, 2012		16,380,000
Net income	16,404			16,404
Total other comprehensive income (loss), net of tax	(2,196)				(2,196)
Cash dividends declared	(8,317)			(8,317)
Share-based compensation	879		879
Deferred compensation plan, shares		2,000
Deferred compensation plan	30	0	30
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit, shares		105,000
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit	918	6	912
Stockholders' Equity, Ending Balance at Jun. 30, 2013	303,370	1,030	93,274	221,761	(12,695)
Common Stock, Shares Outstanding, Ending Balance at Jun. 30, 2013		16,487,000
Stockholders' 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	16,613,561	16,614,000
Net income	19,095			19,095
Total other comprehensive income (loss), net of tax	2,753				2,753
Cash dividends declared	(9,772)			(9,772)
Share-based compensation	961		961
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit, shares		91,000
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit	767	6	761
Stockholders' Equity, Ending Balance at Jun. 30, 2014	$ 343,450	$ 1,044	$ 99,288	$ 241,918	$ 1,200
Common Stock, Shares Outstanding, Ending Balance at Jun. 30, 2014	16,705,427	16,705,000