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, 2014		16,746,000
Shareholders' Equity, Beginning Balance at Dec. 31, 2014	$ 346,279	$ 1,047	$ 101,204	$ 252,837	$ (8,809)
Net income	11,010			11,010
Total other comprehensive income (loss), 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
Common Stock, Shares Outstanding, Ending Balance at Mar. 31, 2015		16,773,000
Shareholders' Equity, Ending Balance at Mar. 31, 2015	$ 353,879	$ 1,048	102,587	258,069	(7,825)
Common Stock, Shares Outstanding, Beginning Balance at Dec. 31, 2015	17,019,578	17,020,000
Shareholders' Equity, Beginning Balance at Dec. 31, 2015	$ 375,388	$ 1,064	110,949	273,074	(9,699)
Net income	10,935			10,935
Total other comprehensive income (loss), net of tax	464				464
Cash dividends declared	(6,199)			(6,199)
Share-based compensation	592		592
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit, shares		4,000
Exercise of stock options, issuance of other compensation-related equity instruments and related tax benefit	$ 100	$ 0	100
Common Stock, Shares Outstanding, Ending Balance at Mar. 31, 2016	17,023,749	17,024,000
Shareholders' Equity, Ending Balance at Mar. 31, 2016	$ 381,280	$ 1,064	$ 111,641	$ 277,810	$ (9,235)