Financing Arrangements (Details 3) (USD $)	12 Months Ended	1 Months Ended		0 Months Ended
	Dec. 31, 2012	Sep. 30, 2012 Previously existing revolving credit facility	Oct. 22, 2012 Previously existing revolving credit facility	Sep. 20, 2012 1.80% Senior Notes due September 25,2017
Long-term debt
Debt, interest rate (as a percent)				1.80%
Aggregate principal Amount				$ 300,000,000
Optional prepayment as a percentage of principal amount plus interest				100.00%
Net proceeds from sale of the notes				297,000,000
Payment of borrowings under revolving credit facility		205,000,000
Line of credit facility, maximum borrowing capacity			1,000,000,000
Debt issuance costs	$ 5,000,000			$ 2,000,000