Fair Value Measurements (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Assets:
Investments	$ 11	$ 9
Foreign Exchange Contracts	4	41
Total Assets at Fair Value	15	50
Liabilities:
Foreign Exchange Contracts	19	18
Total Liabilities at Fair Value	19	18
Supplemental Fair Value Information
Carrying amount — liability	5,427	5,193
Notes payable and overdrafts	262	245
Fixed Rate Debt, Excluding Capital Leases
Supplemental Fair Value Information
Carrying amount — liability	3,616	3,514
Fair value — liability	3,786	3,669
Notes payable and overdrafts	110	123
Variable Rate Debt, Excluding Capital Leases
Supplemental Fair Value Information
Carrying amount — liability	1,811	1,679
Fair value — liability	1,811	1,678
Notes payable and overdrafts	152	122
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)
Assets:
Investments	11	9
Foreign Exchange Contracts	0	0
Total Assets at Fair Value	11	9
Liabilities:
Foreign Exchange Contracts	0	0
Total Liabilities at Fair Value	0	0
Supplemental Fair Value Information
Fair value — liability	3,857	3,804
Significant Other Observable Inputs (Level 2)
Assets:
Investments	0	0
Foreign Exchange Contracts	4	41
Total Assets at Fair Value	4	41
Liabilities:
Foreign Exchange Contracts	19	18
Total Liabilities at Fair Value	19	18
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