Debt (Cash Convertible Notes) (Details) (USD $)			0 Months Ended	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Sep. 15, 2008 Cash Convertible Notes [Member]	Mar. 31, 2012 Cash Convertible Notes [Member]	Dec. 31, 2011 Cash Convertible Notes [Member]	Mar. 31, 2012 Call Options [Member] Cash Convertible Notes [Member]	Dec. 31, 2011 Call Options [Member] Cash Convertible Notes [Member]
Debt Instrument [Line Items]
Long term debt	$ 5,001,595,000	$ 5,168,226,000		$ 994,329,000	$ 937,160,000
Debt				482,700,000	477,200,000
Face amount of debt			575,000,000	575,000,000	575,000,000
Discount on debt				92,300,000	97,800,000
Convertible debt instrument, carrying amount of the equity component				511,600,000	460,000,000
Debt instrument, maturity date			Sep. 15, 2015	Sep. 15, 2015
Convertible debt instrument, fair value of associated derivative transaction						511,600,000	460,000,000
Trading days				20
Consecutive trading days				30
Ratio of observed share price to conversion reference price				130.00%
Conversion reference price of notes				$ 13.32
Reference principal amount of cash convertible notes				$ 1,000
Initial conversion reference rate, per $1,000 principal amount of notes				75.0751