Consolidated Statements of Shareholders' Equity (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Capital Surplus	Accum. Other Compre- hensive Income (Loss)	Retained Earnings	Treasury Stock
Beginning Balance at Dec. 31, 2012	$ 1,021,665	$ 571	$ 515,619	$ 29,208	$ 1,084,477	$ (608,210)
Beginning Balance (in shares) at Dec. 31, 2012		44,754,835
Increase (decrease) in shareholders' equity
Net Income	35,980				35,980
Other Comprehensive Income (Loss)	(9,563)			(9,563)
Share-Based Compensation	1,280		1,280
Common Stock Issued under Purchase and Equity Compensation Plans and Related Tax Benefits	5,271	1	428		(1,553)	6,395
Common Stock Issued under Purchase and Equity Compensation Plans and Related Tax Benefits (in shares)		277,927
Common Stock Repurchased	(8,299)					(8,299)
Common Stock Repurchased (in shares)		(171,427)
Cash Dividends Paid ($0.45 per share)	(20,230)				(20,230)
Ending Balance at Mar. 31, 2013	1,026,104	572	517,327	19,645	1,098,674	(610,114)
Ending Balance (in shares) at Mar. 31, 2013		44,861,335
Beginning Balance at Dec. 31, 2013	1,011,976	572	522,505	(31,823)	1,151,754	(631,032)
Beginning Balance (in shares) at Dec. 31, 2013	44,490,385	44,490,385
Increase (decrease) in shareholders' equity
Net Income	38,592				38,592
Other Comprehensive Income (Loss)	6,427			6,427
Share-Based Compensation	1,808		1,808
Common Stock Issued under Purchase and Equity Compensation Plans and Related Tax Benefits	4,458	1	599		(205)	4,063
Common Stock Issued under Purchase and Equity Compensation Plans and Related Tax Benefits (in shares)		222,762
Common Stock Repurchased	(14,284)					(14,284)
Common Stock Repurchased (in shares)		(245,554)
Cash Dividends Paid ($0.45 per share)	(20,073)				(20,073)
Ending Balance at Mar. 31, 2014	$ 1,028,904	$ 573	$ 524,912	$ (25,396)	$ 1,170,068	$ (641,253)
Ending Balance (in shares) at Mar. 31, 2014	44,467,593	44,467,593