Investments (Securities in a gross unrealized loss position) (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	$ 3,998	$ 9,019
Gross Unrealized Losses, Less than 12 Months	79	267
Estimated Fair Value, 12 Months or Longer	16,646	18,319
Gross Unrealized Losses, 12 Months or Longer	2,207	2,773
Estimated Fair Value, Total	20,644	27,338
Gross Unrealized Losses, Total	2,286	3,040
Corporate and other bonds
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	2,776	5,846
Gross Unrealized Losses, Less than 12 Months	56	165
Estimated Fair Value, 12 Months or Longer	8,576	10,388
Gross Unrealized Losses, 12 Months or Longer	825	1,140
Estimated Fair Value, Total	11,352	16,234
Gross Unrealized Losses, Total	881	1,305
States, municipalities and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	403	1,247
Gross Unrealized Losses, Less than 12 Months	8	52
Estimated Fair Value, 12 Months or Longer	3,471	2,967
Gross Unrealized Losses, 12 Months or Longer	734	783
Estimated Fair Value, Total	3,874	4,214
Gross Unrealized Losses, Total	742	835
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	154	849
Gross Unrealized Losses, Less than 12 Months	1	22
Estimated Fair Value, 12 Months or Longer	2,002	2,010
Gross Unrealized Losses, 12 Months or Longer	365	466
Estimated Fair Value, Total	2,156	2,859
Gross Unrealized Losses, Total	366	488
Commercial mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	36	230
Gross Unrealized Losses, Less than 12 Months	2	3
Estimated Fair Value, 12 Months or Longer	887	988
Gross Unrealized Losses, 12 Months or Longer	78	139
Estimated Fair Value, Total	923	1,218
Gross Unrealized Losses, Total	80	142
Other asset-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	420	680
Gross Unrealized Losses, Less than 12 Months	9	21
Estimated Fair Value, 12 Months or Longer	1,432	1,557
Gross Unrealized Losses, 12 Months or Longer	185	218
Estimated Fair Value, Total	1,852	2,237
Gross Unrealized Losses, Total	194	239
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	610	1,759
Gross Unrealized Losses, Less than 12 Months	12	46
Estimated Fair Value, 12 Months or Longer	4,321	4,555
Gross Unrealized Losses, 12 Months or Longer	628	823
Estimated Fair Value, Total	4,931	6,314
Gross Unrealized Losses, Total	640	869
U.S. Treasury and obligations of government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	78	49
Gross Unrealized Losses, Less than 12 Months	2	1
Estimated Fair Value, 12 Months or Longer	18	41
Gross Unrealized Losses, 12 Months or Longer	1	0
Estimated Fair Value, Total	96	90
Gross Unrealized Losses, Total	3	1
Foreign government
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	131	118
Gross Unrealized Losses, Less than 12 Months	1	3
Estimated Fair Value, 12 Months or Longer	260	368
Gross Unrealized Losses, 12 Months or Longer	19	27
Estimated Fair Value, Total	391	486
Gross Unrealized Losses, Total	$ 20	$ 30