Pension and Postretirement Plans (Summary of Amounts Recognized in the Consolidated Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Noncurrent liabilities	$ (1,044)	$ (867)
Pension Benefits | United States
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	0	0
Current liabilities	(25)	(25)
Noncurrent liabilities	(421)	(328)
Total recognized	(446)	(353)
Pension Benefits | Int’l.
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	29	78
Current liabilities	0	0
Noncurrent liabilities	(211)	(183)
Total recognized	(182)	(105)
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	0	0
Current liabilities	(15)	(16)
Noncurrent liabilities	(211)	(204)
Total recognized	$ (226)	$ (220)