Investments - Amortized Cost and Fair Values of Fixed Maturity Securities (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	$ 43,469	$ 42,615
Gross Unrealized Gains	705	1,022
Gross Unrealized Losses	3,278	2,995
Allowance for Credit Losses	17	16
Estimated Fair Value	40,879	40,626
Corporate and other bonds
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	25,463	25,020
Gross Unrealized Gains	401	597
Gross Unrealized Losses	1,496	1,345
Allowance for Credit Losses		4
Estimated Fair Value	24,368	24,268
States, municipalities and political subdivisions
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	7,560	7,713
Gross Unrealized Gains	269	382
Gross Unrealized Losses	800	703
Allowance for Credit Losses
Estimated Fair Value	7,029	7,392
Residential mortgage-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	3,602	3,411
Gross Unrealized Gains	8	16
Gross Unrealized Losses	495	425
Allowance for Credit Losses
Estimated Fair Value	3,115	3,002
Commercial mortgage-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	1,798	1,862
Gross Unrealized Gains	7	7
Gross Unrealized Losses	186	230
Allowance for Credit Losses	8	8
Estimated Fair Value	1,611	1,631
Other asset-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	3,631	3,515
Gross Unrealized Gains	17	13
Gross Unrealized Losses	260	256
Allowance for Credit Losses	9	4
Estimated Fair Value	3,379	3,268
Asset-backed
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	9,031	8,788
Gross Unrealized Gains	32	36
Gross Unrealized Losses	941	911
Allowance for Credit Losses	17	12
Estimated Fair Value	8,105	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	193	152
Gross Unrealized Gains	1	1
Gross Unrealized Losses	3	2
Allowance for Credit Losses
Estimated Fair Value	191	151
Foreign government
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	742	741
Gross Unrealized Gains	2	6
Gross Unrealized Losses	38	34
Allowance for Credit Losses
Estimated Fair Value	706	713
Fixed maturities available-for-sale
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	42,989	42,414
Gross Unrealized Gains	705	1,022
Gross Unrealized Losses	3,278	2,995
Allowance for Credit Losses	17	16
Estimated Fair Value	40,399	40,425
Fixed maturities trading
Amortized Cost and Fair Values of Fixed Maturity Securities [Abstract]
Cost or Amortized Cost	480	201
Gross Unrealized Gains
Gross Unrealized Losses
Allowance for Credit Losses
Estimated Fair Value	$ 480	$ 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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