Pension and Other Postretirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Settlements	$ 2	$ 3	$ 5	$ 7
Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	2	3
Interest cost	20	13	60	38
Expected return on plan assets	(18)	(20)	(55)	(61)
Recognized net actuarial (gain) loss	7	12	21	37
Settlements	2	3	5	7
Net periodic cost (benefit)	11	9	33	24
Other postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	0	1	1
Interest cost	2	1	5	3
Recognized net actuarial (gain) loss	(1)	0	(2)	1
Amortization of prior service benefit	(3)	(2)	(7)	(7)
Net periodic cost (benefit)	$ (1)	$ (1)	$ (3)	$ (2)