Fair Value Measurements - Changes in balances of Level 3 financial assets carried at fair value (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, beginning balance	$ 1,230	$ 1,102	$ 926
Total realized/unrealized gains (losses) included in Net earnings	76	7	24
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	9	11	(53)
Purchases and issuances	368	270	338
Sales and settlements	(189)	(109)	(117)
Transfer into Level 3	9	46	72
Transfer out of Level 3	(407)	(97)	(88)
Financial assets, ending balance	$ 1,096	1,230	1,102
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Realized gains (losses) on securities
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Asset, Gain (Loss), Statement of Other Comprehensive Income or Comprehensive Income [Extensible Enumeration]	OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax
Fixed maturities
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, beginning balance	$ 736	664	600
Total realized/unrealized gains (losses) included in Net earnings	14	(4)	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	14	11	(53)
Purchases and issuances	164	147	223
Sales and settlements	(132)	(70)	(93)
Transfer into Level 3	9	46	68
Transfer out of Level 3	(37)	(58)	(81)
Financial assets, ending balance	768	736	664
U.S. government agency
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, beginning balance	0	0	0
Total realized/unrealized gains (losses) included in Net earnings	0	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0
Purchases and issuances	0	0	0
Sales and settlements	0	0	0
Transfer into Level 3	0	0	0
Transfer out of Level 3	0	0	0
Financial assets, ending balance	0	0	0
State and municipal
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, beginning balance	2	5	41
Total realized/unrealized gains (losses) included in Net earnings	0	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	(3)
Purchases and issuances	0	0	0
Sales and settlements	(1)	(1)	(1)
Transfer into Level 3	0	1	4
Transfer out of Level 3	0	(3)	(36)
Financial assets, ending balance	1	2	5
Residential MBS
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, beginning balance	2	9	14
Total realized/unrealized gains (losses) included in Net earnings	0	1	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	(1)	(1)
Purchases and issuances	0	0	0
Sales and settlements	0	(3)	(1)
Transfer into Level 3	0	5	7
Transfer out of Level 3	(1)	(9)	(10)
Financial assets, ending balance	1	2	9
Commercial MBS
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, beginning balance	0	0	0
Total realized/unrealized gains (losses) included in Net earnings	0	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0
Purchases and issuances	0	0	0
Sales and settlements	0	0	0
Transfer into Level 3	0	0	0
Transfer out of Level 3	0	0	0
Financial assets, ending balance	0	0	0
Collateralized loan obligations
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, beginning balance	1	2	0
Total realized/unrealized gains (losses) included in Net earnings	(1)	(2)	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	1	0
Purchases and issuances	0	0	0
Sales and settlements	0	0	0
Transfer into Level 3	0	1	2
Transfer out of Level 3	0	(1)	0
Financial assets, ending balance	0	1	2
Other asset-backed securities
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, beginning balance	351	329	278
Total realized/unrealized gains (losses) included in Net earnings	(1)	1	1
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	8	6	(27)
Purchases and issuances	59	55	94
Sales and settlements	(100)	(39)	(52)
Transfer into Level 3	5	31	35
Transfer out of Level 3	(26)	(32)	0
Financial assets, ending balance	296	351	329
Corporate and other
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, beginning balance	380	319	267
Total realized/unrealized gains (losses) included in Net earnings	16	(4)	(1)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	6	5	(22)
Purchases and issuances	105	92	129
Sales and settlements	(31)	(27)	(39)
Transfer into Level 3	4	8	20
Transfer out of Level 3	(10)	(13)	(35)
Financial assets, ending balance	470	380	319
Trading fixed maturities
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, beginning balance	0
Total realized/unrealized gains (losses) included in Net earnings	2
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0
Purchases and issuances	24
Sales and settlements	0
Transfer into Level 3	0
Transfer out of Level 3	0
Financial assets, ending balance	26	0
Equity securities
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, beginning balance	485	427	313
Total realized/unrealized gains (losses) included in Net earnings	60	15	29
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0
Purchases and issuances	174	121	112
Sales and settlements	(57)	(39)	(24)
Transfer into Level 3	0	0	4
Transfer out of Level 3	(370)	(39)	(7)
Financial assets, ending balance	292	485	427
Assets of MIE
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, beginning balance	9	11	13
Total realized/unrealized gains (losses) included in Net earnings	0	(4)	(5)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	(5)	0	0
Purchases and issuances	6	2	3
Sales and settlements	0	0	0
Transfer into Level 3	0	0	0
Transfer out of Level 3	0	0	0
Financial assets, ending balance	$ 10	$ 9	$ 11