Pension, Other Postretirement Benefits and Savings Plans - Changes in Benefit Obligation and Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in benefit obligation:
Curtailments/settlements/termination benefits	$ 6	$ 22	$ 19
Other Postretirement Benefits
Change in benefit obligation:
Beginning balance	(234)	(286)
Newly adopted plans	0	0
Service cost — benefits earned	(2)	(3)	(4)
Interest cost	(11)	(12)	(13)
Plan amendments	0	14
Actuarial (loss) gain	(6)	19
Participant contributions	(12)	(13)
Curtailments/settlements/termination benefits	(2)	0
Foreign currency translation	(5)	15
Benefit payments	31	32
Ending balance	(241)	(234)	(286)
Change in plan assets:
Beginning balance	3	4
Newly adopted plans	0	0
Actual return on plan assets	0	0
Company contributions to plan assets	0	2
Cash funding of direct participant payments	16	16
Participant contributions	12	13
Settlements	0	0
Foreign currency translation	0	0
Benefit payments	(31)	(32)
Ending balance	0	3	4
Funded status at end of year	(241)	(231)
United States
Change in plan assets:
Beginning balance	4,445
Ending balance	4,780	4,445
United States | Pension Plan
Change in benefit obligation:
Beginning balance	(4,734)	(5,331)
Newly adopted plans	0	0
Service cost — benefits earned	(3)	(4)	(4)
Interest cost	(173)	(157)	(160)
Plan amendments	0	0
Actuarial (loss) gain	(477)	315
Participant contributions	0	0
Curtailments/settlements/termination benefits	12	25
Foreign currency translation	0	0
Benefit payments	366	418
Ending balance	(5,009)	(4,734)	(5,331)
Change in plan assets:
Beginning balance	4,445	4,978
Newly adopted plans	0	0
Actual return on plan assets	696	(110)
Company contributions to plan assets	0	0
Cash funding of direct participant payments	20	17
Participant contributions	0	0
Settlements	(15)	(22)
Foreign currency translation	0	0
Benefit payments	(366)	(418)
Ending balance	4,780	4,445	4,978
Funded status at end of year	(229)	(289)
United States | Other Postretirement Benefits
Change in plan assets:
Funded status at end of year	(106)	(112)
Non-U.S.
Change in plan assets:
Beginning balance	2,464
Ending balance	2,740	2,464
Non-U.S. | Pension Plan
Change in benefit obligation:
Beginning balance	(2,774)	(3,109)
Newly adopted plans	(19)	0
Service cost — benefits earned	(26)	(28)	(31)
Interest cost	(69)	(69)	(71)
Plan amendments	2	(29)
Actuarial (loss) gain	(381)	40
Participant contributions	(2)	(2)
Curtailments/settlements/termination benefits	5	113
Foreign currency translation	(62)	177
Benefit payments	131	133
Ending balance	(3,195)	(2,774)	(3,109)
Change in plan assets:
Beginning balance	2,464	2,806
Newly adopted plans	19	0
Actual return on plan assets	252	4
Company contributions to plan assets	39	36
Cash funding of direct participant payments	20	21
Participant contributions	2	2
Settlements	(5)	(112)
Foreign currency translation	80	(160)
Benefit payments	(131)	(133)
Ending balance	2,740	2,464	$ 2,806
Funded status at end of year	(455)	(310)
Non-U.S. | Other Postretirement Benefits
Change in plan assets:
Funded status at end of year	$ (135)	$ (119)