Postretirement Benefit Plans - Plan Assets by Level Three Hierarchy (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 987	$ 869	$ 995
U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		356	330	394
Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2,661	2,410	$ 2,593
Other | U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	987	869
Other | U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	294	271
Other | Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	2,433	2,190
Level 1 | U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Level 1 | U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		62	59
Level 1 | Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		100	80
Level 2 | U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Level 2 | U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Level 2 | Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		128	140
Fixed income securities and cash equivalents | U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		640	563
Fixed income securities and cash equivalents | U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		230	214
Fixed income securities and cash equivalents | Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,947	1,788
Fixed income securities and cash equivalents | Other | U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	640	563
Fixed income securities and cash equivalents | Other | U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	168	155
Fixed income securities and cash equivalents | Other | Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	1,762	1,602
Fixed income securities and cash equivalents | Level 1 | U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Fixed income securities and cash equivalents | Level 1 | U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		62	59
Fixed income securities and cash equivalents | Level 1 | Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		59	47
Fixed income securities and cash equivalents | Level 2 | U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Fixed income securities and cash equivalents | Level 2 | U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Fixed income securities and cash equivalents | Level 2 | Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		126	139
Equity securities | U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		347	306
Equity securities | U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		126	116
Equity securities | Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		714	622
Equity securities | Other | U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	347	306
Equity securities | Other | U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	126	116
Equity securities | Other | Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	671	588
Equity securities | Level 1 | U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Equity securities | Level 1 | U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Equity securities | Level 1 | Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		41	33
Equity securities | Level 2 | U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Equity securities | Level 2 | U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Equity securities | Level 2 | Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 2	$ 1

[1] Consists of bond index and equity index funds, measured at net asset value per share, as well as cash equivalents.