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, 2012	$ 40,421	$ 378,413	$ 447,018	$ 54,334	$ (17,408)	$ 902,778
Balance (in shares) at Dec. 31, 2012	39,625,933
Net income			20,241			20,241
Other comprehensive income, net of tax				(41,122)		(41,122)
Cash dividends declared:
Common, $0.27 per share			(10,735)			(10,735)
Common stock issued under employee stock plan, including tax benefits of $518	350	4,269			293	4,912
Common stock issued under employee stock plan, including tax benefits of $518 (in shares)	363,317
Stock-based compensation		1,220				1,220
Balance at Mar. 31, 2013	$ 40,771	$ 383,902	$ 456,524	$ 13,212	$ (17,115)	$ 877,294
Balance (in shares) at Mar. 31, 2013	39,989,250