Fair Value Measurements Fair Value Tables of Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		$ 266	$ 25	$ 45
Derivative Liability		108	43	10
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]	1,536	1,293	1,055
Marketable Securities		10	5	5
Assets at Fair Value		1,812	1,323	1,105
Liabilities at Fair Value		108	43	10
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Foreign Currency Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	[2]	266	25	45
Derivative Liability	[2]	$ 108	$ 43	$ 10

[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 - Financial Instruments for the classification of derivatives in the interim Condensed Consolidated Balance Sheets.