Debt (Senior Credit Facility) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		3 Months Ended		3 Months Ended	0 Months Ended	3 Months Ended														3 Months Ended
	Mar. 31, 2012 Senior Credit Facility [Member] Y	Jul. 08, 2011 Senior Credit Facility [Member]	Mar. 31, 2012 Incremental Senior Credit Facility [Member]	Jan. 20, 2012 Incremental Senior Credit Facility [Member]	Mar. 31, 2012 Five-Year Senior, Secured, Revolving Credit Facility [Member]	Jan. 20, 2012 Amendment To The Senior Credit Facility [Member]	Mar. 31, 2012 Amendment To The Senior Credit Facility [Member]	Mar. 31, 2012 Eight Scheduled Quarterly [Member] Incremental Senior Credit Facility [Member]	Mar. 31, 2012 Four Scheduled Quarterly [Member] Incremental Senior Credit Facility [Member]	Mar. 31, 2012 Maximum [Member] Senior Credit Facility [Member]	Mar. 31, 2012 Minimum [Member] Senior Credit Facility [Member]	Mar. 31, 2012 Alternative A [Member] Maximum [Member] Libor [Member] Senior Credit Facility [Member]	Mar. 31, 2012 Alternative A [Member] Minimum [Member] Libor [Member] Senior Credit Facility [Member]	Mar. 31, 2012 Alternative B [Member] Federal Funds [Member] Senior Credit Facility [Member]	Mar. 31, 2012 Alternative B [Member] Monthly Libor [Member] Senior Credit Facility [Member]	Mar. 31, 2012 Alternative B [Member] Maximum [Member] Libor [Member] Senior Credit Facility [Member]	Mar. 31, 2012 Alternative B [Member] Minimum [Member] Libor [Member] Senior Credit Facility [Member]	Mar. 31, 2012 Standby Letters Of Credit Guaranteeing Company Industrial Revenue Bonds [Member] Senior Credit Facility [Member]	Mar. 31, 2012 Standby Letters Of Credit Related To Various Insurance Contracts And Foreign Vendor Commitments [Member] Senior Credit Facility [Member]	Mar. 31, 2012 6.125% Notes, Payable January 15, 2016 [Member]	Mar. 31, 2012 7.20% Senior Notes, Payable April 15, 2012 [Member]	Dec. 31, 2011 7.20% Senior Notes, Payable April 15, 2012 [Member]
Line of Credit Facility [Line Items]
Credit facility, initiation date					July 8, 2011		January 20, 2012
Term of line of credit (years)	5
Quarterly principal payments			$ 5,625					$ 1,875	$ 3,750
Payment of financing costs	8,218					1,018
Unamortized financing costs		12,277
Utilized borrowings under credit facility	411,700
Maximum borrowing capacity under credit facility		900,000		150,000
Basis spread on debt instrument												2.00%	1.25%	0.50%	1.00%	1.00%	0.25%
Commitment fee percentage										0.40%	0.25%
Consolidated Interest Coverage Ratio											3.0
Consolidated Net Leverage Ratio										3.75
Amount utilized from long-term lines of credit	509,036																				827,136
Standby letters of credit for various insurance contracts and commitments to foreign vendors																		46,796	50,540
Interest rate percentage																				6.125%	7.20%	7.20%
Available amount under credit facility	$ 540,964