Pension and Other Postretirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Defined Benefit Plan Disclosure [Line Items]
Pension and Other post-retirement benefits - net settlements (E)	$ 0	$ 3	$ 0	$ 3
Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	1	2
Interest cost	19	20	38	40
Expected return on plan assets	(17)	(18)	(35)	(37)
Recognized net actuarial (gain) loss	8	7	16	14
Pension and Other post-retirement benefits - net settlements (E)	0	3	0	3
Net periodic cost (benefit)	10	13	20	22
Other postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	2	1	3	3
Recognized net actuarial (gain) loss	0	0	(1)	(1)
Amortization of prior service benefit	(3)	(2)	(5)	(4)
Net periodic cost (benefit)	$ (1)	$ (1)	$ (3)	$ (2)