Employee Benefits - Reconciliation of the changes in the benefit obligations and fair value of assets and a statement of the funded status (Details) - Pension Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
U.S.
Change in projected benefit obligation
Balance at the beginning of the Period	$ 3,380	$ 3,192
Service cost	0	0	$ 0
Interest cost	57	85	108
Plan amendment	0	0
Settlements	0	0
Actuarial (gain) loss	(103)	274
Benefit payments	(170)	(171)
Foreign currency impact	0	0
Balance at the end of the period	3,164	3,380	3,192
Accumulated benefit obligation at end of year	3,164	3,380
Change in fair value of plan assets
Balance at the beginning of the period	2,276	2,066
Actual return on plan assets	211	289
Employer contributions	61	92
Settlements	0	0
Benefit payments	(170)	(171)
Foreign currency impact	0	0
Balance at the end of the period	2,378	2,276	2,066
Market related value at end of year	2,174	2,076
Funded status	(786)	(1,104)
Unrecognized prior-service cost	0	0
Unrecognized loss	1,551	1,812
Net amount recognized	765	708
U.K.
Change in projected benefit obligation
Balance at the beginning of the Period	5,406	4,779
Service cost	1	0	0
Interest cost	65	88	109
Plan amendment	0	3
Settlements	(14)	(7)
Actuarial (gain) loss	(292)	520
Benefit payments	(189)	(209)
Foreign currency impact	(58)	232
Balance at the end of the period	4,919	5,406	4,779
Accumulated benefit obligation at end of year	4,919	5,406
Change in fair value of plan assets
Balance at the beginning of the period	6,652	5,959
Actual return on plan assets	(136)	618
Employer contributions	9	8
Settlements	(14)	(7)
Benefit payments	(189)	(209)
Foreign currency impact	(76)	283
Balance at the end of the period	6,246	6,652	5,959
Market related value at end of year	6,246	6,652
Funded status	1,327	1,246
Unrecognized prior-service cost	40	43
Unrecognized loss	1,215	1,286
Net amount recognized	2,582	2,575
Other
Change in projected benefit obligation
Balance at the beginning of the Period	1,625	1,425
Service cost	0	0	0
Interest cost	12	19	27
Plan amendment	0	0
Settlements	0	0
Actuarial (gain) loss	24	112
Benefit payments	(47)	(44)
Foreign currency impact	(83)	113
Balance at the end of the period	1,531	1,625	1,425
Accumulated benefit obligation at end of year	1,504	1,592
Change in fair value of plan assets
Balance at the beginning of the period	1,497	1,303
Actual return on plan assets	46	109
Employer contributions	17	20
Settlements	0	0
Benefit payments	(47)	(44)
Foreign currency impact	(83)	109
Balance at the end of the period	1,430	1,497	$ 1,303
Market related value at end of year	1,430	1,497
Funded status	(101)	(128)
Unrecognized prior-service cost	(6)	(7)
Unrecognized loss	489	521
Net amount recognized	$ 382	$ 386