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, 2011		$ 39,394	$ 595,992	$ 884,758	$ (322,454)	$ (438,436)
Balance, shares at Dec. 31, 2011		63,065,931
Net income		0	0	104,546	0	0
Foreign currency translation adjustment	481	0	0	0	0	481
Employee benefit plans	18,732	0	0	0	0	(18,732)
Unrealized gain (loss) on available-for-sale security, net of deferred tax	(226)	0	0	0	0	(226)
Exercise of stock options, including tax, shares		150,213
Exercise of stock options, including tax		94	3,631	0	0	0
Share-based compensation, shares		349,309
Share-based compensation, including tax		213	14,711	(8)	(3,674)	0
Common dividends declared		0	0	(22,357)	0	0
Balance at Dec. 31, 2012		39,701	614,334	966,939	(326,128)	(456,461)
Balance, shares at Dec. 31, 2012		63,565,453
Net income		0	0	99,153	0	0
Foreign currency translation adjustment	871	0	0	0	0	871
Employee benefit plans	(186,059)	0	0	0	0	186,059
Unrealized gain (loss) on available-for-sale security, net of deferred tax	0
Exercise of stock options, including tax, shares		760,495
Exercise of stock options, including tax		475	21,833	0	0	0
Share-based compensation, shares		266,808
Share-based compensation, including tax		173	17,320	0	(2,960)	0
Common dividends declared		0	0	(22,620)	0	0
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
Net income		0	0	137,039	0	0
Foreign currency translation adjustment	(2,731)	0	0	0	0	(2,731)
Employee benefit plans	82,147	0	0	0	0	(82,147)
Unrealized gain (loss) on available-for-sale security, net of deferred tax	0
Exercise of stock options, including tax, shares	926,454	926,454
Exercise of stock options, including tax		579	34,185	0	0	0
Share-based compensation, shares		262,831
Share-based compensation, including tax		173	19,084	0	(3,530)	0
Common stock repurchased, shares	355,000	0
Stock Repurchased During Period, Value	16,800	0	0	0	(16,783)	0
Common dividends declared		0	0	(28,720)	0	0
Balance at Dec. 31, 2014	$ 1,195,838	$ 41,101	$ 706,756	$ 1,151,791	$ (349,401)	$ (354,409)
Balance, shares at Dec. 31, 2014		65,782,041