Debt (Senior Credit Facilities) (Details) (USD $)			3 Months Ended				6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Loans Payable U.S. Term Loans	Mar. 31, 2012 Loans Payable U.S. Term Loans	Dec. 31, 2011 Loans Payable U.S. Term Loans	Nov. 14, 2011 Loans Payable U.S. Term Loans	Jun. 30, 2012 Revolving Credit Facility Revolving Facility	Dec. 31, 2011 Revolving Credit Facility Revolving Facility	Nov. 14, 2011 Revolving Credit Facility Revolving Facility
Debt Instrument [Line Items]
Long term debt	$ 5,261,029,000	$ 5,168,226,000	$ 1,203,125,000		$ 1,250,000,000	$ 1,250,000,000	$ 750,000,000	$ 0
Revolving Facility, Maximum Borrowing Capacity									1,250,000,000
Debt repayment			23,400,000	23,400,000
Revolving Facility, amount outstanding							$ 750,000,000
Interest rate on borrowings							1.85%