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			68,220			68,220
Other comprehensive income, net of tax				47,216		47,216
Cash dividends declared:
Common, $0.86 per share			(34,912)			(34,912)
Common stock issued under employee stock plan, including tax benefits of $1,476	270	5,712			133	6,115
Common stock issued under employee stock plan, including tax benefits of $1,476 (in shares)	275,967
Stock-based compensation		3,073				3,073
Balance at Sep. 30, 2014	$ 41,483	$ 405,313	$ 515,040	$ 20,670	$ (16,982)	$ 965,524
Balance (in shares) at Sep. 30, 2014	40,707,285