Investments (Securities in a gross unrealized loss position) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	$ 28,394	$ 5,695
Gross Unrealized Losses, Less than 12 Months	4,152	92
Estimated Fair Value, 12 Months or Longer	1,550	370
Gross Unrealized Losses, 12 Months or Longer	431	20
Estimated Fair Value, Total	29,944	6,065
Gross Unrealized Losses, Total	4,583	112
Corporate and other bonds
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	16,707	2,389
Gross Unrealized Losses, Less than 12 Months	2,117	48
Estimated Fair Value, 12 Months or Longer	914	136
Gross Unrealized Losses, 12 Months or Longer	281	8
Estimated Fair Value, Total	17,621	2,525
Gross Unrealized Losses, Total	2,398	56
States, municipalities and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	4,793	730
Gross Unrealized Losses, Less than 12 Months	1,029	14
Estimated Fair Value, 12 Months or Longer	128	0
Gross Unrealized Losses, 12 Months or Longer	51	0
Estimated Fair Value, Total	4,921	730
Gross Unrealized Losses, Total	1,080	14
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	6,387	2,410
Gross Unrealized Losses, Less than 12 Months	963	25
Estimated Fair Value, 12 Months or Longer	483	229
Gross Unrealized Losses, 12 Months or Longer	93	12
Estimated Fair Value, Total	6,870	2,639
Gross Unrealized Losses, Total	1,056	37
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	2,582	1,043
Gross Unrealized Losses, Less than 12 Months	462	8
Estimated Fair Value, 12 Months or Longer	17	0
Gross Unrealized Losses, 12 Months or Longer	8	0
Estimated Fair Value, Total	2,599	1,043
Gross Unrealized Losses, Total	470	8
Commercial mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	1,372	527
Gross Unrealized Losses, Less than 12 Months	194	7
Estimated Fair Value, 12 Months or Longer	233	167
Gross Unrealized Losses, 12 Months or Longer	43	12
Estimated Fair Value, Total	1,605	694
Gross Unrealized Losses, Total	237	19
Other asset-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	2,433	840
Gross Unrealized Losses, Less than 12 Months	307	10
Estimated Fair Value, 12 Months or Longer	233	62
Gross Unrealized Losses, 12 Months or Longer	42	0
Estimated Fair Value, Total	2,666	902
Gross Unrealized Losses, Total	349	10
U.S. Treasury and obligations of government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	61	69
Gross Unrealized Losses, Less than 12 Months	1	3
Estimated Fair Value, 12 Months or Longer	0	5
Gross Unrealized Losses, 12 Months or Longer	0	0
Estimated Fair Value, Total	61	74
Gross Unrealized Losses, Total	1	3
Foreign government
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	446	97
Gross Unrealized Losses, Less than 12 Months	42	2
Estimated Fair Value, 12 Months or Longer	25	0
Gross Unrealized Losses, 12 Months or Longer	6	0
Estimated Fair Value, Total	471	97
Gross Unrealized Losses, Total	$ 48	$ 2

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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