Fair Value Measurements Fair Value Tables of Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Millions		Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		$ 74	$ 72	$ 55
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		20	21	54
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value		115	5,775	9,883
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents and Restricted Cash Equivalents	[1]	1,568	1,221	759
Marketable Securities		117	5	142
Assets at Fair Value		1,759	1,298	956
Long-term Debt, Fair Value	[2]	123	6,100	10,397
Liabilities at Fair Value		143	6,121	10,451
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	[3]	74	72	55
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	[3]	$ 20	$ 21	$ 54

[1] Time deposits included in cash and cash equivalents and money market funds included in other current assets in the interim Condensed Consolidated Balance Sheets are held at amortized cost, which approximates fair value.

[2] See Note 17 - Short-Term Borrowings, Long-Term Debt and Available Credit Facilities, for information on fair value measurements of long-term debt.

[3] See Note 22 - Financial Instruments for the classification of derivatives in the interim Condensed Consolidated Balance Sheets.