Investments (Summary Of Aggregate Market Value And Gross Unrealized Depreciation Of Fixed Maturity And Equity Securities, By Security Type) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Market Value	$ 14,960.0	$ 8,094.0
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Gross Unrealized Depreciation	(1,659.0)	(128.0)
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Market Value	3,023.0	1,241.0
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(651.0)	(75.0)
Fixed maturity securities, Duration of Unrealized Loss, Total, Market Value	17,983.0	9,335.0
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(2,310.0)	(203.0)
No Recorded Allowance for Credit Losses [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Market Value	14,937.0
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Gross Unrealized Depreciation	(1,640.0)
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Market Value	3,023.0
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(651.0)
Fixed maturity securities, Duration of Unrealized Loss, Total, Market Value	17,960.0
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(2,291.0)
U.S. Treasury Securities And Obligations Of U.S. Government Agencies And Corporations [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Market Value	807.0	504.0
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Gross Unrealized Depreciation	(47.0)	(6.0)
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Market Value	273.0	92.0
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(32.0)	(4.0)
Fixed maturity securities, Duration of Unrealized Loss, Total, Market Value	1,080.0	596.0
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(79.0)	(10.0)
Obligations Of U.S. States And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Market Value	326.0	51.0
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Gross Unrealized Depreciation	(30.0)	(1.0)
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Market Value	25.0	3.0
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(8.0)
Fixed maturity securities, Duration of Unrealized Loss, Total, Market Value	351.0	54.0
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(38.0)	(1.0)
Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Market Value	4,247.0	2,133.0
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Gross Unrealized Depreciation	(447.0)	(38.0)
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Market Value	996.0	473.0
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(189.0)	(24.0)
Fixed maturity securities, Duration of Unrealized Loss, Total, Market Value	5,243.0	2,605.0
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(636.0)	(63.0)
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Market Value	2,827.0	1,954.0
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Gross Unrealized Depreciation	(158.0)	(11.0)
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Market Value	55.0	42.0
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(5.0)	(1.0)
Fixed maturity securities, Duration of Unrealized Loss, Total, Market Value	2,882.0	1,996.0
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(164.0)	(12.0)
Mortgage-Backed Securities: Commercial [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Market Value	877.0	222.0
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Gross Unrealized Depreciation	(104.0)	(3.0)
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Market Value	27.0	40.0
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(4.0)	(3.0)
Fixed maturity securities, Duration of Unrealized Loss, Total, Market Value	904.0	262.0
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(108.0)	(6.0)
Mortgage Backed Securities: Agency residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Market Value	2,086.0	1,101.0
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Gross Unrealized Depreciation	(222.0)	(12.0)
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Market Value	588.0	280.0
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(115.0)	(7.0)
Fixed maturity securities, Duration of Unrealized Loss, Total, Market Value	2,674.0	1,381.0
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(337.0)	(19.0)
Mortgage Backed Securities: Non-agency residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Market Value	3.0	2.0
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Gross Unrealized Depreciation
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Market Value	2.0
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation
Fixed maturity securities, Duration of Unrealized Loss, Total, Market Value	5.0	2.0
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total
Foreign Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Market Value	971.0	392.0
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Gross Unrealized Depreciation	(137.0)	(10.0)
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Market Value	250.0	101.0
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(68.0)	(18.0)
Fixed maturity securities, Duration of Unrealized Loss, Total, Market Value	1,221.0	493.0
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(205.0)	(28.0)
Foreign Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Market Value	2,792.0	1,735.0
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Gross Unrealized Depreciation	(496.0)	(46.0)
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Market Value	808.0	211.0
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(229.0)	(18.0)
Fixed maturity securities, Duration of Unrealized Loss, Total, Market Value	3,600.0	1,945.0
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(726.0)	(65.0)
Recorded an Allowance for Credit Losses [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Market Value	23.0
Fixed maturity securities, Duration of Unrealized Loss, Less than 12 months, Gross Unrealized Depreciation	(19.0)
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Market Value
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation
Fixed maturity securities, Duration of Unrealized Loss, Total, Market Value	23.0	16.0
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	$ (19.0)	$ (0.4)

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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