Lines of Credit and Financing Arrangements (Asset Securitization Program, Textuals) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Jul. 05, 2016	Dec. 31, 2015	Nov. 30, 2015
Line of Credit Facility [Line Items]
Maximum securitization, amount				$ 220,000,000.0
Maximum securitization as percentage of net pool balance	100.00%
Program fee (as a percent)	0.65%
Average floating commercial paper rate (as a percent)	1.66%		1.06%
Unused fee (as a percent)	102.00%
Fixed rate of agreement (as a percent)	0.325%
Unused fee charged on incremental available amounts (as a percent)	0.05%
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
Maximum [Member]
Line of Credit Facility [Line Items]
Amount Available Under Asset Securitization		$ 325,000,000
Minimum [Member]
Line of Credit Facility [Line Items]
Asset Securitization Unused Fee Charge On Incremental Amount above	$ 200,000,000
Amount Available Under Asset Securitization		$ 200,000,000	$ 180,000,000