Fair Value Measurements (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Assets:
Investments	$ 60	$ 56
Foreign Exchange Contracts	13	30
Total Assets at Fair Value	73	86
Liabilities:
Foreign Exchange Contracts	16	4
Total Liabilities at Fair Value	16	4
Fair Value of Long Term Debt, excluding Capital Leases
Carrying amount - liability	6,014	6,305
Fixed Rate Debt, Excluding Capital Leases
Fair Value of Long Term Debt, excluding Capital Leases
Carrying amount - liability	4,079	4,132
Fair Value - liability	4,331	4,225
Variable Rate Debt, Excluding Capital Leases
Fair Value of Long Term Debt, excluding Capital Leases
Carrying amount - liability	1,935	2,173
Fair Value - liability	1,937	2,170
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)
Assets:
Investments	60	56
Foreign Exchange Contracts	0	0
Total Assets at Fair Value	60	56
Liabilities:
Foreign Exchange Contracts	0	0
Total Liabilities at Fair Value	0	0
Fair Value of Long Term Debt, excluding Capital Leases
Fair Value - liability	4,546	4,603
Significant Other Observable Inputs (Level 2)
Assets:
Investments	0	0
Foreign Exchange Contracts	13	30
Total Assets at Fair Value	13	30
Liabilities:
Foreign Exchange Contracts	16	4
Total Liabilities at Fair Value	16	4
Significant Unobservable Inputs (Level 3)
Assets:
Investments	0	0
Foreign Exchange Contracts	0	0
Total Assets at Fair Value	0	0
Liabilities:
Foreign Exchange Contracts	0	0
Total Liabilities at Fair Value	$ 0	$ 0