Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated Other Comprehensive Income (Loss), Net of Tax (Changes in AOCI) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (504)	$ (489)	$ (377)
Other Comprehensive Income (Loss) before Reclassifications	143	(11)	(38)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	11	(4)	7
Net Current Period Other Comprehensive Income (Loss)	154	(15)	(31)
Ending Balance	(350)	(504)	(489)
Net Change in Accumulated Other Comprehensive Income			(112)
Cumulative Effect, Period of Adoption, Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(81)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(9)	(15)	(1)
Other Comprehensive Income (Loss) before Reclassifications	0	(4)	(17)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	3	10	3
Net Current Period Other Comprehensive Income (Loss)	3	6	(14)
Ending Balance	(6)	(9)	(15)
Net Change in Accumulated Other Comprehensive Income			(14)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] \| Cumulative Effect, Period of Adoption, Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			0
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(545)	(499)	(360)
Other Comprehensive Income (Loss) before Reclassifications	176	(58)	(70)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	14	12	12
Net Current Period Other Comprehensive Income (Loss)	190	(46)	(58)
Ending Balance	(355)	(545)	(499)
Net Change in Accumulated Other Comprehensive Income			(139)
Accumulated Defined Benefit Plans Adjustment [Member] \| Cumulative Effect, Period of Adoption, Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(81)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	50	25	(16)
Other Comprehensive Income (Loss) before Reclassifications	(33)	51	49
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	(6)	(26)	(8)
Net Current Period Other Comprehensive Income (Loss)	(39)	25	41
Ending Balance	$ 11	$ 50	25
Net Change in Accumulated Other Comprehensive Income			41
Accumulated Net Unrealized Investment Gain (Loss) [Member] \| Cumulative Effect, Period of Adoption, Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			$ 0