Pension and Other Postretirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Settlements	$ 3	$ 3	$ 4	$ 6
Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	2	2
Interest cost	13	12	25	24
Expected return on plan assets	(21)	(23)	(41)	(46)
Recognized net actuarial loss	12	15	25	29
Settlements	3	3	4	6
Net periodic benefit	8	8	15	15
Other postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	1	1
Interest cost	1	2	2	3
Recognized net actuarial loss	1	0	1	0
Amortization of prior service benefit	(3)	(3)	(5)	(4)
Net periodic benefit	$ 0	$ 0	$ (1)	$ 0