Accumulated Other Comprehensive Income (Loss), Net of Tax (Changes of AOCI) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	$ (410)	$ (542)	$ (350)	$ (504)	$ (504)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(53)	16	(118)	(24)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	8	4	13	6
Other Comprehensive Income (Loss), net of tax	(45)	20	(105)	(18)
Accumulated Other Comprehensive Income (Loss), Ending Balance	(455)	(522)	(455)	(522)	(350)
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	(5)	(8)	(6)	(9)	(9)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0	0	0	0
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	0	0	1	1	3
Other Comprehensive Income (Loss), net of tax	0	0	1	1
Accumulated Other Comprehensive Income (Loss), Ending Balance	(5)	(8)	(5)	(8)	(6)
Pension and OPEB Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	(355)	(542)	(355)	(545)	(545)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0	0	0
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	1	4	1	7
Other Comprehensive Income (Loss), net of tax	1	4	1	7
Accumulated Other Comprehensive Income (Loss), Ending Balance	(354)	(538)	(354)	(538)	(355)
Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	(50)	8	11	50	50
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(53)	16	(118)	(24)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	7	0	11	(2)
Other Comprehensive Income (Loss), net of tax	(46)	16	(107)	(26)
Accumulated Other Comprehensive Income (Loss), Ending Balance	$ (96)	$ 24	$ (96)	$ 24	$ 11