Debt (Senior Convertible Notes) (Details) (USD $)	6 Months Ended			1 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Mar. 31, 2012 Convertible Debt Senior Convertible Notes	Jun. 30, 2012 Convertible Debt Senior Convertible Notes	Dec. 31, 2011 Convertible Debt Senior Convertible Notes
Debt Instrument [Line Items]
Repayment of debt	$ 732,549,000	$ 2,466,000		$ 600,000,000
Long term debt	5,261,029,000		5,168,226,000		0	593,983,000
Discount on debt						$ 6,000,000