Consolidated Statements of Changes in Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Beginning balance at Dec. 31, 2011	$ 490,526	$ 74,285	$ 52,637	$ 421,468	$ (14,108)	$ (43,756)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	34,200			34,200
Other comprehensive income (loss), net of tax	526				526
Cash dividends declared	(17,357)			(17,357)
Common stock issued in acquisition	27,610	3,708	23,902
Treasury stock issued	998			(2,272)		3,270
Recognition of restricted stock compensation expense	949		949
Tax (expense) benefit from stock-based compensation	(30)		(30)
Ending balance at Dec. 31, 2012	537,422	77,993	77,458	436,039	(13,582)	(40,486)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	50,539			50,539
Other comprehensive income (loss), net of tax	888				888
Cash dividends declared	(18,137)			(18,137)
Treasury stock issued	(88)			(283)		195
Recognition of restricted stock compensation expense	586		586
Tax (expense) benefit from stock-based compensation	96		96
Ending balance at Dec. 31, 2013	571,306	77,993	78,140	468,158	(12,694)	(40,291)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	57,910			57,910
Other comprehensive income (loss), net of tax	(1,139)				(1,139)
Cash dividends declared	(20,203)			(20,203)
Treasury stock issued	(163)			(1,805)		1,642
Recognition of restricted stock compensation expense	933		933
Tax (expense) benefit from stock-based compensation	16		16
Issuance costs	(271)		(271)
Ending balance at Dec. 31, 2014	$ 608,389	$ 77,993	$ 78,818	$ 504,060	$ (13,833)	$ (38,649)