Investments (Securities in a gross unrealized loss position) (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	$ 25,746	$ 5,695
Gross Unrealized Losses, Less than 12 Months	2,728	92
Estimated Fair Value, 12 Months or Longer	617	370
Gross Unrealized Losses, 12 Months or Longer	114	20
Estimated Fair Value, Total	26,363	6,065
Gross Unrealized Losses, Total	2,842	112
Corporate and other bonds
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	14,827	2,389
Gross Unrealized Losses, Less than 12 Months	1,366	48
Estimated Fair Value, 12 Months or Longer	322	136
Gross Unrealized Losses, 12 Months or Longer	74	8
Estimated Fair Value, Total	15,149	2,525
Gross Unrealized Losses, Total	1,440	56
States, municipalities and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	4,121	730
Gross Unrealized Losses, Less than 12 Months	666	14
Estimated Fair Value, 12 Months or Longer	32	0
Gross Unrealized Losses, 12 Months or Longer	10	0
Estimated Fair Value, Total	4,153	730
Gross Unrealized Losses, Total	676	14
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	6,280	2,410
Gross Unrealized Losses, Less than 12 Months	662	25
Estimated Fair Value, 12 Months or Longer	237	229
Gross Unrealized Losses, 12 Months or Longer	27	12
Estimated Fair Value, Total	6,517	2,639
Gross Unrealized Losses, Total	689	37
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	2,374	1,043
Gross Unrealized Losses, Less than 12 Months	305	8
Estimated Fair Value, 12 Months or Longer	3	0
Gross Unrealized Losses, 12 Months or Longer	0	0
Estimated Fair Value, Total	2,377	1,043
Gross Unrealized Losses, Total	305	8
Commercial mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	1,552	527
Gross Unrealized Losses, Less than 12 Months	143	7
Estimated Fair Value, 12 Months or Longer	149	167
Gross Unrealized Losses, 12 Months or Longer	21	12
Estimated Fair Value, Total	1,701	694
Gross Unrealized Losses, Total	164	19
Other asset-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	2,354	840
Gross Unrealized Losses, Less than 12 Months	214	10
Estimated Fair Value, 12 Months or Longer	85	62
Gross Unrealized Losses, 12 Months or Longer	6	0
Estimated Fair Value, Total	2,439	902
Gross Unrealized Losses, Total	220	10
U.S. Treasury and obligations of government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	82	69
Gross Unrealized Losses, Less than 12 Months	6	3
Estimated Fair Value, 12 Months or Longer	3	5
Gross Unrealized Losses, 12 Months or Longer	1	0
Estimated Fair Value, Total	85	74
Gross Unrealized Losses, Total	7	3
Foreign government
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	436	97
Gross Unrealized Losses, Less than 12 Months	28	2
Estimated Fair Value, 12 Months or Longer	23	0
Gross Unrealized Losses, 12 Months or Longer	2	0
Estimated Fair Value, Total	459	97
Gross Unrealized Losses, Total	$ 30	$ 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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