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Financial Instruments (Derivative) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 2,623	$ 4,217
Restricted Cash and Cash Equivalents, Current	218	110
Restricted Cash and Cash Equivalents, Noncurrent	165	128
Total cash, cash equivalents, restricted cash and restricted cash equivalents presented in the consolidated statements of cash flows	3,006	4,455	$ 4,141	$ 4,710
Credit Derivative, Maximum Exposure, Undiscounted	37
Bank Time Deposits [Member]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 1,400	$ 2,300