Debt, Credit Facility (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Line of Credit Facility [Line Items]
Long-term Debt	$ 798,600,000	$ 619,400,000
Credit Agreement, covenant compliance	June 30, 2011
Credit Agreement, covenant compliance, actual leverage ratio	1.4
Credit Agreement, covenant terms, maximum leverage ratio	3.5
Credit Agreement, covenant compliance, actual interest coverage ratio	15.9
Credit Agreement, covenant terms, minimum interest coverage ratio	3.5
2011 Credit Agreement [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	1,500,000,000
Credit Agreement, available funds	1,424,500,000
Letters of credit outstanding amount	75,500,000
Line of Credit Facility, Maximum Borrowing Capacity	2,250,000,000
Combined Domestic and European Credit Agreements [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	915,000,000
2011 Credit Agreement [Member]
Line of Credit Facility [Line Items]
Long-term Debt	$ 0	$ 0
Interest rate percentage, minimum	1.13%
Interest rate percentage	1.43%