Investments (Summary of fixed maturity and equity securities) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	$ 41,032	$ 39,945
Gross Unrealized Gains	652	4,558
Gross Unrealized Losses	4,056	112
Allowance for Credit Losses	1	18	$ 40
Estimated Fair Value	37,627	44,373
Debt Securities, Trading, Unrealized Gain (Loss) [Abstract]
Total fixed maturity securities trading	0	7
Total fixed maturity securities trading	0	7
Debt securities, amortized cost	41,032	39,952
Total fixed maturity securities	37,627	44,380
Corporate and other bonds
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	23,137	21,444
Gross Unrealized Gains	301	2,755
Gross Unrealized Losses	2,009	56
Allowance for Credit Losses	0	11	23
Estimated Fair Value	21,429	24,132
Debt Securities, Trading, Unrealized Gain (Loss) [Abstract]
Total fixed maturity securities	22,117	24,852
States, municipalities and political subdivisions
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	8,918	10,358
Gross Unrealized Gains	338	1,599
Gross Unrealized Losses	939	14
Allowance for Credit Losses	0	0
Estimated Fair Value	8,317	11,943
Debt Securities, Trading, Unrealized Gain (Loss) [Abstract]
Total fixed maturity securities	8,317	11,943
Residential mortgage-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	3,073	2,893
Gross Unrealized Gains	5	71
Gross Unrealized Losses	447	8
Allowance for Credit Losses	0	0
Estimated Fair Value	2,631	2,956
Commercial mortgage-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	1,886	1,987
Gross Unrealized Gains	4	63
Gross Unrealized Losses	255	19
Allowance for Credit Losses	0	0
Estimated Fair Value	1,635	2,031
Other asset-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	3,287	2,561
Gross Unrealized Gains	2	54
Gross Unrealized Losses	361	10
Allowance for Credit Losses	1	7
Estimated Fair Value	2,927	2,598
Asset-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	8,246	7,441
Gross Unrealized Gains	11	188
Gross Unrealized Losses	1,063	37
Allowance for Credit Losses	1	7	$ 17
Estimated Fair Value	7,193	7,585
Debt Securities, Trading, Unrealized Gain (Loss) [Abstract]
Total fixed maturity securities	7,193	7,585
U.S. Treasury and obligations of government-sponsored enterprises
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	111	132
Gross Unrealized Gains	1	1
Gross Unrealized Losses	2	3
Allowance for Credit Losses	0	0
Estimated Fair Value	110	130
Foreign government
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	617	570
Gross Unrealized Gains	1	15
Gross Unrealized Losses	43	2
Allowance for Credit Losses	0	0
Estimated Fair Value	575	583
Redeemable preferred stock
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	3	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Allowance for Credit Losses	0	0
Estimated Fair Value	$ 3	$ 0

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