Investments - Amortized Cost and Fair Values of Fixed Maturity Securities (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	$ 44,028	$ 42,615
Gross Unrealized Gains	1,281	1,022
Gross Unrealized Losses	2,236	2,995
Allowance for Credit Losses	18	16
Estimated Fair Value	43,055	40,626
Corporate and other bonds
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	25,872	25,020
Gross Unrealized Gains	826	597
Gross Unrealized Losses	900	1,345
Allowance for Credit Losses	6	4
Estimated Fair Value	25,792	24,268
States, municipalities and political subdivisions
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	7,406	7,713
Gross Unrealized Gains	359	382
Gross Unrealized Losses	617	703
Allowance for Credit Losses
Estimated Fair Value	7,148	7,392
Residential mortgage-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	3,684	3,411
Gross Unrealized Gains	32	16
Gross Unrealized Losses	362	425
Allowance for Credit Losses
Estimated Fair Value	3,354	3,002
Commercial mortgage-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	1,816	1,862
Gross Unrealized Gains	14	7
Gross Unrealized Losses	141	230
Allowance for Credit Losses		8
Estimated Fair Value	1,689	1,631
Other asset-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	3,743	3,515
Gross Unrealized Gains	40	13
Gross Unrealized Losses	186	256
Allowance for Credit Losses	12	4
Estimated Fair Value	3,585	3,268
Asset-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	9,243	8,788
Gross Unrealized Gains	86	36
Gross Unrealized Losses	689	911
Allowance for Credit Losses	12	12
Estimated Fair Value	8,628	7,901
U.S. Treasury and obligations of government-sponsored enterprises
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	224	152
Gross Unrealized Gains	2	1
Gross Unrealized Losses	4	2
Allowance for Credit Losses
Estimated Fair Value	222	151
Foreign government
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	755	741
Gross Unrealized Gains	8	6
Gross Unrealized Losses	26	34
Allowance for Credit Losses
Estimated Fair Value	737	713
Fixed maturities available-for-sale
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	43,500	42,414
Gross Unrealized Gains	1,281	1,022
Gross Unrealized Losses	2,236	2,995
Allowance for Credit Losses	18	16
Estimated Fair Value	42,527	40,425
Fixed maturities trading
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	528	201
Gross Unrealized Gains
Gross Unrealized Losses
Allowance for Credit Losses
Estimated Fair Value	$ 528	$ 201

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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