Fair Value Measurements Narrative (Details) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 4,100,000,000	$ 3,800,000,000
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, net asset (liability)	$ 0	$ 0