Supplementary Information Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Millions	Jun. 30, 2019		Dec. 31, 2018		Jun. 30, 2018		Dec. 31, 2017
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 2,077		$ 2,270		$ 2,696
Restricted Cash	319
Cash, Cash Equivalents, and Restricted Cash - Continuing Operations	2,513	[1]	5,024		5,011	[1]	$ 7,914
Cash and cash equivalents of discontinued operations	0		2,254		1,799
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations	2,513		5,024		5,011
Other Current Assets [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash	436		460		471
Restricted cash of discontinued operations	0		40	[2]	45	[2]
Continuing Operations [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Cash, Cash Equivalents, and Restricted Cash - Continuing Operations	$ 2,513		$ 2,730		$ 3,167

[1] See page 26 for reconciliation of cash and cash equivalents and restricted cash presented in interim Condensed Consolidated Balance Sheets to total cash, cash equivalents and restricted cash presented in the interim Condensed Consolidated Statements of Cash Flows.

[2] Amount included within other current assets. Refer to Note 5 - Divestitures and Other Transactions, for additional information.