Investments - Amortized Cost and Fair Values of Fixed Maturity Securities (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	$ 45,283	$ 44,196
Gross Unrealized Gains	863	715
Gross Unrealized Losses	2,738	3,039
Allowance for Credit Losses	51	45
Estimated Fair Value	43,357	41,827
Corporate and other bonds
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	26,205	25,839
Gross Unrealized Gains	566	423
Gross Unrealized Losses	1,069	1,305
Allowance for Credit Losses	14	13
Estimated Fair Value	25,688	24,944
States, municipalities and political subdivisions
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	8,044	7,396
Gross Unrealized Gains	223	243
Gross Unrealized Losses	892	835
Allowance for Credit Losses
Estimated Fair Value	7,375	6,804
Asset-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	9,435	9,274
Gross Unrealized Gains	67	42
Gross Unrealized Losses	746	868
Allowance for Credit Losses	37	32
Estimated Fair Value	8,719	8,416
Residential mortgage-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	3,947	3,725
Gross Unrealized Gains	25	7
Gross Unrealized Losses	427	488
Allowance for Credit Losses
Estimated Fair Value	3,545	3,244
Commercial mortgage-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	1,705	1,779
Gross Unrealized Gains	17	11
Gross Unrealized Losses	106	141
Allowance for Credit Losses	18	18
Estimated Fair Value	1,598	1,631
Other asset-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	3,783	3,770
Gross Unrealized Gains	25	24
Gross Unrealized Losses	213	239
Allowance for Credit Losses	19	14
Estimated Fair Value	3,576	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	231	220
Gross Unrealized Gains		1
Gross Unrealized Losses	5	1
Allowance for Credit Losses
Estimated Fair Value	226	220
Foreign government
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	744	701
Gross Unrealized Gains	7	6
Gross Unrealized Losses	26	30
Allowance for Credit Losses
Estimated Fair Value	725	677
Fixed maturities available-for-sale
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	44,659	43,430
Gross Unrealized Gains	863	715
Gross Unrealized Losses	2,738	3,039
Allowance for Credit Losses	51	45
Estimated Fair Value	42,733	41,061
Fixed maturities trading
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	624	766
Gross Unrealized Gains
Gross Unrealized Losses
Allowance for Credit Losses
Estimated Fair Value	$ 624	$ 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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