Investments (Summary of fixed maturity and equity securities) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022		Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	$ 42,364		$ 41,032
Gross Unrealized Gains	396		652
Gross Unrealized Losses	4,888		4,056
Allowance for Credit Losses	18	$ 22	1		$ 3	$ 5	$ 18
Estimated Fair Value	37,854		37,627
Total fixed maturity securities trading
Debt securities, amortized cost	42,366		41,032
Total fixed maturity securities	37,856		37,627	[1]
Corporate and other bonds
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	24,757		23,137
Gross Unrealized Gains	196		301
Gross Unrealized Losses	2,437		2,009
Allowance for Credit Losses	5	13	0		0	0	11
Estimated Fair Value	22,511		21,429
Total fixed maturity securities trading
Total fixed maturity securities	23,320		22,117
States, municipalities and political subdivisions
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	8,003		8,918
Gross Unrealized Gains	183		338
Gross Unrealized Losses	1,152		939
Allowance for Credit Losses	0		0
Estimated Fair Value	7,034		8,317
Total fixed maturity securities trading
Total fixed maturity securities	7,034		8,317
Asset-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	8,741		8,246
Gross Unrealized Gains	15		11
Gross Unrealized Losses	1,241		1,063
Allowance for Credit Losses	13	$ 9	1		$ 3	$ 5	$ 7
Estimated Fair Value	7,502		7,193
Total fixed maturity securities trading
Total fixed maturity securities	7,502		7,193
Residential mortgage-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	3,425		3,073
Gross Unrealized Gains	4		5
Gross Unrealized Losses	599		447
Allowance for Credit Losses	0		0
Estimated Fair Value	2,830		2,631
Commercial mortgage-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	1,833		1,886
Gross Unrealized Gains	4		4
Gross Unrealized Losses	276		255
Allowance for Credit Losses	7		0
Estimated Fair Value	1,554		1,635
Other asset-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	3,483		3,287
Gross Unrealized Gains	7		2
Gross Unrealized Losses	366		361
Allowance for Credit Losses	6		1
Estimated Fair Value	3,118		2,927
U.S. Treasury and obligations of government-sponsored enterprises
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	150		111
Gross Unrealized Gains	1		1
Gross Unrealized Losses	2		2
Allowance for Credit Losses	0		0
Estimated Fair Value	149		110
Foreign government
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	713		617
Gross Unrealized Gains	1		1
Gross Unrealized Losses	56		43
Allowance for Credit Losses	0		0
Estimated Fair Value	658		575
Redeemable preferred stock
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	0		3
Gross Unrealized Gains	0		0
Gross Unrealized Losses	0		0
Allowance for Credit Losses	0		0
Estimated Fair Value	0		3
Total fixed maturity securities trading
Total fixed maturity securities trading
Cost or Amortized Cost	2		0
Estimated Fair Value	$ 2		$ 0

[1] As of January 1, 2023, the Company adopted ASU 2018-12 using the modified retrospective method applied as of the transition date of January 1, 2021. Prior period amounts in the financial statements have been adjusted to reflect application of the new guidance. See Note A to the Condensed Consolidated Financial Statements for additional information.