Fair Value Measurements and Disclosures (Details 3) - USD ($) $ in Millions		Mar. 31, 2017	Dec. 31, 2016
Reported Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	[1]	$ 6,700	$ 6,699
Estimate of Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	[1]	$ 7,200	$ 7,112

[1] (1) Net of unamortized discount, premium and debt issuance costs and excludes capital lease and other obligations.