Fair Value Measurements - Assets and liabilities measured and carried at fair value in the financial statements (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Assets:
Available for sale (AFS) fixed maturities	$ 10,398	$ 10,377
Trading fixed maturities	76	57
Equity securities, at fair value	751	1,018
Assets of managed investment entities	4,140	4,484
Other assets — derivatives	82	87
Total assets accounted for at fair value	15,366	15,942
Liabilities:
Liabilities of managed investment entities	3,965	4,307
Other liabilities — derivatives	18	22
Total liabilities accounted for at fair value	3,985	4,331
Contingent consideration - acquisitions
Liabilities:
Contingent consideration — acquisitions	2	2
Other liabilities — derivatives
Liabilities:
Other liabilities — derivatives	18	22
Fixed maturities
Assets:
Available for sale (AFS) fixed maturities	10,398	10,377
Trading fixed maturities	76	57
U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities	173	236
States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities	859	984
Foreign government
Assets:
Available for sale (AFS) fixed maturities	237	230
Residential MBS
Assets:
Available for sale (AFS) fixed maturities	1,989	1,658
Commercial MBS
Assets:
Available for sale (AFS) fixed maturities	51	74
Collateralized loan obligations
Assets:
Available for sale (AFS) fixed maturities	1,237	1,687
Other asset-backed securities
Assets:
Available for sale (AFS) fixed maturities	2,356	2,362
Corporate and other
Assets:
Available for sale (AFS) fixed maturities	3,496	3,146
Equity securities
Assets:
Equity securities, at fair value	751	1,018
Other assets
Assets:
Other assets — derivatives	1	6
Level 1
Assets:
Assets of managed investment entities	419	335
Total assets accounted for at fair value	1,023	1,079
Liabilities:
Liabilities of managed investment entities	402	322
Total liabilities accounted for at fair value	402	322
Level 1 | Contingent consideration - acquisitions
Liabilities:
Contingent consideration — acquisitions	0	0
Level 1 | Other liabilities — derivatives
Liabilities:
Other liabilities — derivatives	0	0
Level 1 | Fixed maturities
Assets:
Available for sale (AFS) fixed maturities	185	244
Trading fixed maturities	0	0
Level 1 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities	173	235
Level 1 | States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 1 | Foreign government
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 1 | Residential MBS
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 1 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 1 | Collateralized loan obligations
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 1 | Other asset-backed securities
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 1 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities	12	9
Level 1 | Equity securities
Assets:
Equity securities, at fair value	419	500
Level 1 | Other assets
Assets:
Other assets — derivatives	0	0
Level 2
Assets:
Assets of managed investment entities	3,711	4,140
Total assets accounted for at fair value	13,247	13,633
Liabilities:
Liabilities of managed investment entities	3,553	3,976
Total liabilities accounted for at fair value	3,571	3,998
Level 2 | Contingent consideration - acquisitions
Liabilities:
Contingent consideration — acquisitions	0	0
Level 2 | Other liabilities — derivatives
Liabilities:
Other liabilities — derivatives	18	22
Level 2 | Fixed maturities
Assets:
Available for sale (AFS) fixed maturities	9,445	9,397
Trading fixed maturities	50	57
Level 2 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities	0	1
Level 2 | States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities	858	982
Level 2 | Foreign government
Assets:
Available for sale (AFS) fixed maturities	237	230
Level 2 | Residential MBS
Assets:
Available for sale (AFS) fixed maturities	1,988	1,656
Level 2 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities	51	74
Level 2 | Collateralized loan obligations
Assets:
Available for sale (AFS) fixed maturities	1,237	1,686
Level 2 | Other asset-backed securities
Assets:
Available for sale (AFS) fixed maturities	2,060	2,011
Level 2 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities	3,014	2,757
Level 2 | Equity securities
Assets:
Equity securities, at fair value	40	33
Level 2 | Other assets
Assets:
Other assets — derivatives	1	6
Level 3
Assets:
Assets of managed investment entities	10	9
Total assets accounted for at fair value	1,096	1,230
Liabilities:
Liabilities of managed investment entities	10	9
Total liabilities accounted for at fair value	12	11
Level 3 | Contingent consideration - acquisitions
Liabilities:
Contingent consideration — acquisitions	2	2
Level 3 | Other liabilities — derivatives
Liabilities:
Other liabilities — derivatives	0	0
Level 3 | Fixed maturities
Assets:
Available for sale (AFS) fixed maturities	768	736
Trading fixed maturities	26	0
Level 3 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 3 | States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities	1	2
Level 3 | Foreign government
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 3 | Residential MBS
Assets:
Available for sale (AFS) fixed maturities	1	2
Level 3 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 3 | Collateralized loan obligations
Assets:
Available for sale (AFS) fixed maturities	0	1
Level 3 | Other asset-backed securities
Assets:
Available for sale (AFS) fixed maturities	296	351
Level 3 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities	470	380
Level 3 | Equity securities
Assets:
Equity securities, at fair value	292	485
Level 3 | Other assets
Assets:
Other assets — derivatives	$ 0	$ 0