Pensions and Other Benefits - Details Relating to Pension Benefits and Other Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Benefits
Change in benefit obligations [Roll Forward]
Benefit obligations at January 1	$ 6,186	$ 5,822
Service cost	53	51	$ 44
Interest cost	163	193	237
UPI acquisition	0	246
Actuarial losses (gains)	(202)	400
Exchange rate loss	(3)	3
Settlements, curtailments and termination benefits	(358)	4
Benefits paid	(417)	(533)
Benefit obligations at December 31	5,422	6,186	5,822
Change in plan assets
Fair value of plan at January 1	6,035	5,406
Actual return on plan assets	394	922
UPI acquisition	0	238
Asset reversion	0	0
Employer contributions	0	0
Settlements	(380)	0
Benefits paid from plan assets	(417)	(531)
Fair value of plan assets at December 31	5,632	6,035	5,406
Funded status of plans at December 31	210	(151)
Other Benefits
Change in benefit obligations [Roll Forward]
Benefit obligations at January 1	1,841	1,876
Service cost	11	12	13
Interest cost	50	63	91
UPI acquisition	0	56
Actuarial losses (gains)	(171)	(23)
Exchange rate loss	0	0
Settlements, curtailments and termination benefits	19	4
Benefits paid	(130)	(147)
Benefit obligations at December 31	1,620	1,841	1,876
Change in plan assets
Fair value of plan at January 1	2,111	2,025
Actual return on plan assets	70	219
UPI acquisition	0	1
Asset reversion	(4)	(38)
Employer contributions	2	1
Settlements	0	0
Benefits paid from plan assets	(85)	(97)
Fair value of plan assets at December 31	2,094	2,111	$ 2,025
Funded status of plans at December 31	$ 474	$ 270