Investments - Amortized Cost and Fair Values of Fixed Maturity Securities (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	$ 45,338	$ 44,196
Gross Unrealized Gains	1,134	715
Gross Unrealized Losses	2,295	3,039
Allowance for Credit Losses	61	45
Estimated Fair Value	44,116	41,827
Corporate and other bonds
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	25,592	25,839
Gross Unrealized Gains	734	423
Gross Unrealized Losses	844	1,305
Allowance for Credit Losses	21	13
Estimated Fair Value	25,461	24,944
States, municipalities and political subdivisions
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	8,840	7,396
Gross Unrealized Gains	301	243
Gross Unrealized Losses	765	835
Allowance for Credit Losses
Estimated Fair Value	8,376	6,804
Asset-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	9,464	9,274
Gross Unrealized Gains	89	42
Gross Unrealized Losses	660	868
Allowance for Credit Losses	40	32
Estimated Fair Value	8,853	8,416
Residential mortgage-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	4,041	3,725
Gross Unrealized Gains	42	7
Gross Unrealized Losses	382	488
Allowance for Credit Losses
Estimated Fair Value	3,701	3,244
Commercial mortgage-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	1,633	1,779
Gross Unrealized Gains	19	11
Gross Unrealized Losses	88	141
Allowance for Credit Losses	22	18
Estimated Fair Value	1,542	1,631
Other asset-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	3,790	3,770
Gross Unrealized Gains	28	24
Gross Unrealized Losses	190	239
Allowance for Credit Losses	18	14
Estimated Fair Value	3,610	3,541
U.S. Treasury and obligations of government-sponsored enterprises
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	226	220
Gross Unrealized Gains		1
Gross Unrealized Losses	3	1
Allowance for Credit Losses
Estimated Fair Value	223	220
Foreign government
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	736	701
Gross Unrealized Gains	10	6
Gross Unrealized Losses	23	30
Allowance for Credit Losses
Estimated Fair Value	723	677
Fixed maturities available-for-sale
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	44,858	43,430
Gross Unrealized Gains	1,134	715
Gross Unrealized Losses	2,295	3,039
Allowance for Credit Losses	61	45
Estimated Fair Value	43,636	41,061
Fixed maturities trading
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	480	766
Gross Unrealized Gains
Gross Unrealized Losses
Allowance for Credit Losses
Estimated Fair Value	$ 480	$ 766

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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Amount, before tax, of unrealized loss 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).

+ References

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

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Amount excluding accrued interest, of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

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