CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2011	$ 774,583	$ 37,795	$ 313,501	$ 411,805	$ 29,165	$ (17,683)
Balance (in shares) at Dec. 31, 2011		36,986,409
Net income	18,826			18,826
Other comprehensive loss, net of tax	(4,168)				(4,168)
Dividends declared:
Common, $0.26 per share	(10,216)			(10,216)
Common stock issued under Employee stock plan, including tax benefits of $660	5,508	315	5,043			150
Common stock issued under Employee stock plan, including tax benefits of $660 (in shares)		322,863
Stock-based compensation	1,223		1,223
Common stock issuance	54,917	2,130	52,787
Common stock issuance (in shares)		2,129,800
Balance at Mar. 31, 2012	$ 840,673	$ 40,240	$ 372,554	$ 420,415	$ 24,997	$ (17,533)
Balance (in shares) at Mar. 31, 2012		39,439,072