Employee Benefits - Amounts recognized in the Consolidated Statements of Financial Position (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prepaid pension	$ 1,366	$ 1,280
Pension Plan | U.S.
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prepaid pension	0	0
Accrued benefit liability - current	(52)	(52)
Accrued benefit liability - non-current	(734)	(1,052)
Accumulated other comprehensive loss	1,551	1,812
Net amount recognized	765	708
Pension Plan | U.K.
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prepaid pension	1,344	1,268
Accrued benefit liability - current	(1)	(1)
Accrued benefit liability - non-current	(16)	(21)
Accumulated other comprehensive loss	1,255	1,329
Net amount recognized	2,582	2,575
Pension Plan | Other
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prepaid pension	0	0
Accrued benefit liability - current	(5)	(5)
Accrued benefit liability - non-current	(96)	(123)
Accumulated other comprehensive loss	483	514
Net amount recognized	$ 382	$ 386