Long-term Debt (Details) (USD $) In Millions, except Share data, unless otherwise specified					3 Months Ended			3 Months Ended			3 Months Ended				3 Months Ended				3 Months Ended							3 Months Ended
	Mar. 31, 2012		Dec. 31, 2011		Mar. 31, 2012 6.25% Senior Unsecured Notes due 2014		Dec. 31, 2011 6.25% Senior Unsecured Notes due 2014	Mar. 31, 2012 10.00% Senior Unsecured Notes due 2017		Dec. 31, 2011 10.00% Senior Unsecured Notes due 2017	Mar. 31, 2012 4.00% Senior Notes due 2022		Mar. 02, 2012 4.00% Senior Notes due 2022	Dec. 31, 2011 4.00% Senior Notes due 2022	Mar. 31, 2012 4.75% Convertible Senior Notes due 2023		Mar. 15, 2013 4.75% Convertible Senior Notes due 2023	Dec. 31, 2011 4.75% Convertible Senior Notes due 2023	Mar. 31, 2012 4.25% Convertible Senior Notes due 2023		Mar. 15, 2012 4.25% Convertible Senior Notes due 2023	Dec. 31, 2011 4.25% Convertible Senior Notes due 2023	Mar. 31, 2012 Other notes payable and capitalized leases		Dec. 31, 2011 Other notes payable and capitalized leases	Mar. 31, 2012 4.25% Convertible Senior Notes due 2023
Debt Instrument
Effective Interest Rate					6.29%			10.38%			4.13%				3.50%
Book Value					$ 353.9		$ 354.3	$ 590.9		$ 590.6	$ 246.9			$ 0	$ 202.2			$ 202.7	$ 0			$ 403.0	$ 65.6		$ 65.1
Long-term Debt, Fair Value					382.4	[1]	374.5	688.5	[1]	690.0	245.0	[1]	246.8	0	226.5	[1]		220.5	0	[1]		405.5	64.5	[1]
Total long-term debt	1,459.5		1,615.7
Less: current portion	219.8	[2]	404.8	[2]
Long-term debt, excluding current portion	1,239.7		1,210.9
Unamortized Discount					0.3			9.1			3.1		3.2
Unamortized Premium															2.2
Stated Interest Rate					6.25%			10.00%			4.00%				4.75%				4.25%
Debt Maturity Date					Nov. 15, 2014			Jul. 15, 2017			Mar. 15, 2022				Mar. 15, 2023				Mar. 15, 2023
Repurchase of convertible notes for cash, date																	Mar. 15, 2013				Mar. 15, 2012
4.00% Notes, Face Value													250.0
4.00% Notes, Frequency of Periodic Payment											semi-annually
4.00% Notes, Date of First Required Payment											September 15, 2012
4.00% Notes, Capitalized Direct Fees											2.5
Repurchase price percentage due to change of control											101.00%
4.25% Notes, Amount Retired																			400.0
4.25% Notes, Amount Retired for Cash																			399.6
4.25% Notes Retirement, Accrued Interest Paid																			0.5
Conversion of 4.25% Notes, Amount																			$ 0.4
Conversion of 4.25% Notes, Shares Issued																			30,000
4.25% Notes, Conversion Rate																			82.4612
4.25% Notes, Incremental Common Shares if Converted																										33,000,000

[1] See Note 10 for information on the fair value measurement of our long-term debt.

[2] On March 15, 2013, holders of our 4.75% Convertible Senior Notes due 2023 (the “4.75% Notes”) may require us to repurchase their notes for cash at par and as such, we included these notes in the current portion of long-term debt on our March 31, 2012 unaudited Consolidated Balance Sheet. The 4.75% Notes are redeemable in whole or in part at our option beginning March 15, 2013. Any 4.75% Notes not repurchased on March 15, 2013 and not called for redemption by us will be reclassified to long-term debt. On March 15, 2012, holders of our 4.25% Convertible Senior Notes due 2023 (the “4.25% Notes”) could have required us to repurchase their notes for cash at par and therefore, we included these notes in the current portion of long-term debt on our December 31, 2011 Consolidated Balance Sheet.