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Financial Instruments (Derivative) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 1,602	$ 2,020
Restricted Cash and Cash Equivalents, Current	113	100
Restricted Cash and Cash Equivalents, Noncurrent	152	158
Total cash, cash equivalents, restricted cash and restricted cash equivalents presented in the consolidated statements of cash flows	1,867	2,278	$ 3,112	$ 4,455
Credit Derivative, Maximum Exposure, Undiscounted	34
Bank Time Deposits [Member]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 400	$ 1,300