Long-term Debt (Details) (USD $) In Millions, unless otherwise specified					1 Months Ended	12 Months Ended				12 Months Ended				12 Months Ended				12 Months Ended				12 Months Ended						1 Months Ended		12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Aug. 31, 2011 7.25% Senior Unsecured Notes due 2011	Dec. 31, 2011 7.25% Senior Unsecured Notes due 2011		Dec. 31, 2010 7.25% Senior Unsecured Notes due 2011		Dec. 31, 2011 6.25% Senior Unsecured Notes due 2014		Dec. 31, 2010 6.25% Senior Unsecured Notes due 2014		Dec. 31, 2011 10.00% Senior Unsecured Notes due 2017		Dec. 31, 2010 10.00% Senior Unsecured Notes due 2017		Dec. 31, 2011 4.75% Convertible Senior Notes due 2023		Dec. 31, 2010 4.75% Convertible Senior Notes due 2023		Dec. 31, 2011 4.25% Convertible Senior Notes due 2023		Dec. 31, 2010 4.25% Convertible Senior Notes due 2023		Dec. 31, 2011 Other notes payable and capitalized leases	Dec. 31, 2010 Other notes payable and capitalized leases	Nov. 30, 2010 Floating Rate Senior Unsecured Notes due 2010	Apr. 30, 2010 Floating Rate Senior Unsecured Notes due 2010	Dec. 31, 2010 Floating Rate Senior Unsecured Notes due 2010
Debt Instrument
Effective Interest Rate						7.25%				6.29%				10.38%				3.50%				0.58%
Stated Interest Rate						7.25%				6.25%				10.00%				4.75%				4.25%
Debt Maturity Date						Aug. 15, 2011				Nov. 15, 2014				Jul. 15, 2017				Mar. 15, 2023				Mar. 15, 2023								Nov. 15, 2010
Book Value						$ 0		$ 36.3		$ 354.3		$ 353.3		$ 590.6		$ 589.4		$ 202.7		$ 205.0		$ 403.0		$ 417.4		$ 65.1	$ 20.8
Fair Value						0	[1]	37.0	[1]	374.5	[1]	378.0	[1]	690.0	[1]	705.0	[1]	220.5	[1]	235.0	[1]	405.5	[1]	444.4	[1]
Total long-term debt	1,615.7		1,622.2
Less: current portion	404.8	[2]	38.9	[2]
Long-term debt, excluding current portion	1,210.9		1,583.3
Unamortized Discount										0.3				9.4
Unamortized Premium																		2.7				3.0
Unamortized debt issuance costs	25.5		28.3
Aggregate principal amount					36.3																							192.3	21.4
Repayment of long term debt, amount paid, including accrued and unpaid interest					37.6																							193.5	21.5
Cash debt pooling arrangements, amount netted	$ 1,106.6		$ 916.1

[1] Fair values are derived from trading quotes by institutions making a market in the securities and estimations of value by those institutions using proprietary models.

[2] On March 15, 2012, holders of our 4.25% Convertible Senior Notes due 2023 (the “4.25% Notes”) may require us to repurchase their notes for cash at par, and accordingly, we included these notes in the current portion of long-term debt on our December 31, 2011 Consolidated Balance Sheet. The 4.25% Notes are redeemable in whole or in part at our option beginning March 15, 2012. Any 4.25% Notes not repurchased on March 15, 2012 and not called for redemption by us will be reclassified to long-term debt. On August 15, 2011, our 7.25% Senior Unsecured Notes due 2011 (the "2011 Notes") matured. Therefore we included these notes in current portion of long-term debt on our December 31, 2010 Consolidated Balance Sheet.