Pension and Other Postretirement Benefits - Components of Net Periodic Cost (Benefit) and Amounts Recognized in Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Components of net periodic cost:
Settlements	$ 0	$ 0	$ 10
Other comprehensive income (loss):
Deferred income taxes	14	108	25
Recognized in other comprehensive income (loss), net of tax	45	337	75
Discontinued operations
Components of net periodic cost:
Net periodic cost (benefit)	7	3	3
Pension Benefits
Components of net periodic cost:
Service cost	0	0	0
Interest cost	207	150	145
Expected return on plan assets	(128)	(172)	(188)
Amortization of actuarial losses (gains)	83	97	93
Settlements	0	0	10
Net periodic cost (benefit)	162	75	60
Other comprehensive income (loss):
Actuarial (loss) gain	(22)	325	(27)
Share of equity investee	0	1	1
Settlements	0	0	10
Amortization of actuarial losses (gains)	83	97	93
Recognized in other comprehensive income, before tax	61	423	77
Deferred income taxes	(14)	(103)	(19)
Recognized in other comprehensive income (loss), net of tax	47	320	58
Postretirement Benefits
Components of net periodic cost:
Service cost	1	1	1
Interest cost	12	8	8
Expected return on plan assets	0	0	0
Amortization of actuarial losses (gains)	(18)	(15)	(15)
Settlements	0	0	0
Net periodic cost (benefit)	(5)	(6)	(6)
Other comprehensive income (loss):
Actuarial (loss) gain	11	29	18
Share of equity investee	0	0	0
Settlements	0	0	0
Amortization of actuarial losses (gains)	(18)	(15)	(15)
Recognized in other comprehensive income, before tax	(7)	14	3
Deferred income taxes	2	(3)	(1)
Recognized in other comprehensive income (loss), net of tax	$ (5)	$ 11	$ 2