Long-Term Debt (Fair Value And Carrying Value Of Debt Instruments) (Details) (USD $) In Thousands, unless otherwise specified			12 Months Ended				0 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 7.20% Senior Notes, Payable April 15, 2012 [Member]	Dec. 31, 2011 7.20% Senior Notes, Payable April 15, 2012 [Member]	Dec. 31, 2002 7.20% Senior Notes, Payable April 15, 2012 [Member]	Sep. 29, 2012 7.20% Senior Notes, Payable April 15, 2012 [Member]	Jan. 17, 2006 6.125% Notes, Payable January 15, 2016 [Member]	Dec. 31, 2012 6.125% Notes, Payable January 15, 2016 [Member]	Dec. 31, 2011 6.125% Notes, Payable January 15, 2016 [Member]	Dec. 31, 2012 Five Year Senior Secured Credit Facility, Due July 8, 2016 [Member]	Dec. 31, 2011 Five Year Senior Secured Credit Facility, Due July 8, 2016 [Member]	Dec. 31, 2012 Fair Value [Member]	Dec. 31, 2011 Fair Value [Member]	Dec. 31, 2012 Fair Value [Member] 7.20% Senior Notes, Payable April 15, 2012 [Member]	Dec. 31, 2011 Fair Value [Member] 7.20% Senior Notes, Payable April 15, 2012 [Member]	Dec. 31, 2012 Fair Value [Member] 6.125% Notes, Payable January 15, 2016 [Member]	Dec. 31, 2011 Fair Value [Member] 6.125% Notes, Payable January 15, 2016 [Member]	Dec. 31, 2012 Fair Value [Member] Five Year Senior Secured Credit Facility, Due July 8, 2016 [Member]	Dec. 31, 2011 Fair Value [Member] Five Year Senior Secured Credit Facility, Due July 8, 2016 [Member]	Dec. 31, 2012 Carrying Value [Member]	Dec. 31, 2011 Carrying Value [Member]	Dec. 31, 2012 Carrying Value [Member] 7.20% Senior Notes, Payable April 15, 2012 [Member]	Dec. 31, 2011 Carrying Value [Member] 7.20% Senior Notes, Payable April 15, 2012 [Member]	Dec. 31, 2012 Carrying Value [Member] 6.125% Notes, Payable January 15, 2016 [Member]	Dec. 31, 2011 Carrying Value [Member] 6.125% Notes, Payable January 15, 2016 [Member]	Dec. 31, 2012 Carrying Value [Member] Five Year Senior Secured Credit Facility, Due July 8, 2016 [Member]	Dec. 31, 2011 Carrying Value [Member] Five Year Senior Secured Credit Facility, Due July 8, 2016 [Member]	Dec. 31, 2012 Secured Credit Facility [Member]	Dec. 31, 2012 Secured Credit Facility [Member] Fair Value [Member]	Dec. 31, 2011 Secured Credit Facility [Member] Fair Value [Member]	Dec. 31, 2012 Secured Credit Facility [Member] Carrying Value [Member]	Dec. 31, 2011 Secured Credit Facility [Member] Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes payable														$ 0	$ 336,606	$ 1,011,600	$ 963,900	$ 153,875	$ 298,000			$ 0	$ 336,270	$ 900,000	$ 900,000	$ 153,875	$ 298,000
Utilized borrowings under credit facility																												280,000	280,000	0	280,000	0
Industrial revenue bonds, capital leases and other												49,067	52,169							49,067	52,169
Total long-term debt												1,494,542	1,650,675							1,382,942	1,586,439
Current portion of long-term debt	55,213	386,255										55,213	386,591							55,213	386,255
Long-term debt, less current portion												$ 1,439,329	$ 1,264,084							$ 1,327,729	$ 1,200,184
Interest rate percentage			7.20%	7.20%	7.20%	7.20%	6.125%	6.125%	6.125%
Notes payable, maturity date			Apr. 15, 2012	Apr. 15, 2012	Apr. 15, 2012		Jan. 15, 2016	Jan. 15, 2016	Jan. 15, 2016	Jul. 08, 2016	Jul. 08, 2016
Term of line of credit (years)										5 years	5 years