Statements Of Consolidated Shareholders' Equity (USD $) In Thousands, except Share data	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Repurchased Common Stock	Accumulated Other Comprehensive Loss
Balance at Dec. 31, 2010		$ 39,143	$ 580,008	$ 821,187	$ (340,912)	$ (279,894)
Balance, shares at Dec. 31, 2010		62,750,994
Net Income	88,443			88,443
Foreign currency translation adjustment	(1,331)					(1,331)
Employee benefit plans	157,205					(157,205)
Unrealized gain (loss) on available-for-sale security, net of deferred tax	6					(6)
Exercise of stock options, including tax, shares		244,944
Exercise of stock options, including tax		153	6,008
Share-based compensation, shares		69,993
Share-based compensation, net of tax		98	9,976	(73)	(1,471)
Repurchased common stock issued under defined contribution plan			0	(2,622)	19,929
Common dividends declared				(22,177)
Balance at Dec. 31, 2011		39,394	595,992	884,758	(322,454)	(438,436)
Balance, shares at Dec. 31, 2011		63,065,931
Net Income	104,546			104,546
Foreign currency translation adjustment	481					481
Employee benefit plans	18,732					(18,732)
Unrealized gain (loss) on available-for-sale security, net of deferred tax	(226)					226
Exercise of stock options, including tax, shares		150,213
Exercise of stock options, including tax		94	3,631
Share-based compensation, shares		349,309
Share-based compensation, net of tax		213	14,711	(8)	(3,674)
Common dividends declared				(22,357)	0
Balance at Dec. 31, 2012	838,385	39,701	614,334	966,939	(326,128)	(456,461)
Balance, shares at Dec. 31, 2012		63,565,453
Net Income	99,153			99,153
Foreign currency translation adjustment	871					871
Employee benefit plans	(186,059)					186,059
Unrealized gain (loss) on available-for-sale security, net of deferred tax	0
Exercise of stock options, including tax, shares	760,495	760,495
Exercise of stock options, including tax		475	21,833
Share-based compensation, shares		266,808
Share-based compensation, net of tax		173	17,320	0	(2,960)
Common dividends declared				(22,620)
Balance at Dec. 31, 2013	$ 1,138,689	$ 40,349	$ 653,487	$ 1,043,472	$ (329,088)	$ (269,531)
Balance, shares at Dec. 31, 2013		64,592,756