Employee Benefit Plans - Level 3 Rollforward (Details) - United Kingdom - Pension - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Beginning balance	$ 1,363	$ 2,363
Foreign currency exchange rate changes	70	(236)
Ending balance	1,402	1,363	$ 2,363
Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Beginning balance	214
Ending balance	136	214
Real estate funds | Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Beginning balance	214	269	237
Actual return on plan assets still held at period end	(87)	(27)	35
Foreign currency exchange rate changes	9	(28)	(3)
Ending balance	$ 136	$ 214	$ 269