CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2011	$ 37,795	$ 313,501	$ 411,805	$ 29,165	$ (17,683)	$ 774,583
Balance (in shares) at Dec. 31, 2011	36,986,409
Net income			39,897			39,897
Other comprehensive income, net of tax				28,002		28,002
Dividends declared:
Common, $0.52 per share			(20,476)			(20,476)
Common stock issued under employee stock plan, including tax benefits of $720	348	5,602			150	6,100
Common stock issued under Employee stock plan, including tax benefits of $720 (in shares)	355,720
Stock-based compensation		2,036				2,036
Common stock issuance	2,130	52,787				54,917
Common stock issuance (in shares)	2,129,800					2,130,000
Balance at Jun. 30, 2012	$ 40,273	$ 373,926	$ 431,226	$ 57,167	$ (17,533)	$ 885,059
Balance (in shares) at Jun. 30, 2012	39,471,929