Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income (Loss), Net of Tax (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Deferred Taxes
Balance	$ (98)	$ (43)	$ (95)	$ (39)
Changes in value	2	(2)		(5)
Amounts reclassified to earnings	0	(2)		(3)
Balance	(96)	(47)	(96)	(47)
Total
Balance	3,624	5,206	5,029	5,960
Changes in value	(6)	9	(1)	18
Amounts reclassified to earnings	(1)	3	(1)	7
Balance	3,964	4,904	3,964	4,904
Accumulated Other Comprehensive Income (Loss)
Total
Balance	(937)	(1,126)	(942)	(1,139)
Balance	(944)	(1,114)	(944)	(1,114)
Deferred income tax expense	285		285
Pension and Other Postretirement Liabilities
Before Tax
Balance	(839)	(1,084)	(847)	(1,102)
Changes in value	6	11	14	24
Amounts reclassified to earnings	(1)	5	(1)	10
Balance	(834)	(1,068)	(834)	(1,068)
Investments and Other
Before Tax
Balance	0	1	0	2
Changes in value	(14)	0	(14)	(1)
Amounts reclassified to earnings	0	0	0	0
Balance	$ (14)	$ 1	$ (14)	$ 1