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, 2013	$ 41,213	$ 396,528	$ 481,732	$ (26,546)	$ (17,115)	$ 875,812
Balance (in shares) at Dec. 31, 2013	40,431,318
Net income			45,850			45,850
Other comprehensive income, net of tax				48,388		48,388
Cash dividends declared:
Common, $0.56 per share			(22,722)			(22,722)
Common stock issued under employee stock plan, including tax benefits of $1,435	251	5,215			133	5,599
Common stock issued under employee stock plan, including tax benefits of $1,435 (in shares)	256,632
Stock-based compensation		2,088				2,088
Balance at Jun. 30, 2014	$ 41,464	$ 403,831	$ 504,860	$ 21,842	$ (16,982)	$ 955,015
Balance (in shares) at Jun. 30, 2014	40,687,950