Retirement Benefits - Net Pension Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Net pension expense (benefit)	$ 0	$ (29)	$ 0
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	14	18	14
Interest cost	4	2	2
Expected return on plan assets	(6)	(6)	(6)
Amortization of prior service cost	(5)	(6)	(8)
Amortization of net actuarial loss	1	2	3
Net curtailments and settlements (Note 7)	0	(29)	0
Net pension expense (benefit)	$ 8	$ (19)	$ 5