Employee Benefit Plans - Sumamry of Balance Sheet Components (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Consolidated Balance Sheet for pension and other postretirement benefit plans
Noncurrent employee benefit plans	$ (7,866)	$ (6,654)
Pension Benefits | U.S.
Consolidated Balance Sheet for pension and other postretirement benefit plans
Deferred charges and other assets	23	17
Accrued liabilities	(239)	(180)
Noncurrent employee benefit plans	(4,072)	(3,031)
Net amount recognized at December 31	(4,288)	(3,194)
Pension Benefits | Int’l.
Consolidated Balance Sheet for pension and other postretirement benefit plans
Deferred charges and other assets	413	412
Accrued liabilities	(71)	(66)
Noncurrent employee benefit plans	(1,231)	(1,024)
Net amount recognized at December 31	(889)	(678)
Other Benefits
Consolidated Balance Sheet for pension and other postretirement benefit plans
Deferred charges and other assets	0	0
Accrued liabilities	(174)	(175)
Noncurrent employee benefit plans	(2,346)	(2,255)
Net amount recognized at December 31	$ (2,520)	$ (2,430)