Lines of Credit and Financing Arrangements (Domestic Credit Facility) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Nov. 13, 2014	Nov. 12, 2014
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity		$ 650,000,000	$ 650,000,000
Domestic Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity		950,000,000
Outstanding borrowings	$ 323,000,000
Standby letters of credit	4,400,000
Line of credit, available for future borrowings	600,100,000
Maximum increase in credit facility	350,000,000
Domestic Credit Facility [Member] | Medium-term Notes [Member]
Line of Credit Facility [Line Items]
Debt instrument, face amount		$ 300,000,000
Outstanding borrowings	277,500,000
Quarterly principal repayments	7,500,000
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	150,000,000
Subfacility for Swingline Loans [Member]
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	65,000,000
Line of Credit [Member]
Line of Credit Facility [Line Items]
Minimum amount of principal or interest due on indebtedness or receivable securitization	$ 75,000,000.0