Investments (Summary of fixed maturity and equity securities) (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025	Dec. 31, 2024
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	$ 45,060	$ 44,668
Gross Unrealized Gains	813	1,089
Gross Unrealized Losses	2,568	2,286
Allowance for Credit Losses	75	69	$ 47	$ 45
Estimated Fair Value	43,230	43,402
Corporate and other bonds
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	25,624	25,484
Gross Unrealized Gains	482	682
Gross Unrealized Losses	1,074	881
Allowance for Credit Losses	31	28	15	13
Estimated Fair Value	25,001	25,257
States, municipalities and political subdivisions
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	9,110	8,870
Gross Unrealized Gains	255	303
Gross Unrealized Losses	793	742
Allowance for Credit Losses	0	0
Estimated Fair Value	8,572	8,431
Residential mortgage-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	4,035	4,011
Gross Unrealized Gains	37	50
Gross Unrealized Losses	372	366
Allowance for Credit Losses	0	0
Estimated Fair Value	3,700	3,695
Commercial mortgage-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	1,548	1,566
Gross Unrealized Gains	13	18
Gross Unrealized Losses	81	80
Allowance for Credit Losses	21	21
Estimated Fair Value	1,459	1,483
Other asset-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	3,722	3,729
Gross Unrealized Gains	19	28
Gross Unrealized Losses	219	194
Allowance for Credit Losses	23	20
Estimated Fair Value	3,499	3,543
Asset-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	9,305	9,306
Gross Unrealized Gains	69	96
Gross Unrealized Losses	672	640
Allowance for Credit Losses	44	41	$ 32	$ 32
Estimated Fair Value	8,658	8,721
U.S. Treasury and obligations of government-sponsored enterprises
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	244	236
Gross Unrealized Gains	1	1
Gross Unrealized Losses	3	3
Allowance for Credit Losses	0	0
Estimated Fair Value	242	234
Foreign government
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	769	764
Gross Unrealized Gains	6	7
Gross Unrealized Losses	26	20
Allowance for Credit Losses	0	0
Estimated Fair Value	749	751
Redeemable preferred stock
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	8	8
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Allowance for Credit Losses	0	0
Estimated Fair Value	$ 8	$ 8

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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-Publisher FASB
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
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