Employee Retirement Benefits - Components of Net Periodic Costs for Qualified and Supplemental Pension Plans (Details) - Qualified Pension Plans - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Defined Benefit Plan Disclosure
Service cost	$ 2	$ 3	$ 3	$ 5
Interest cost	3	2	6	5
Expected return on plan assets	(5)	(5)	(10)	(11)
Amortization of actuarial loss and prior service cost	(1)	0	(2)	0
Other	0	0	(5)	0
Total non-service benefit	(3)	(3)	(11)	(6)
Net periodic benefit cost	$ (1)	$ 0	$ (8)	$ (1)