Fair Value Measurements - Changes in balances of Level 3 financial assets carried at fair value (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	$ 1,382	$ 1,160	$ 1,230	$ 1,102
Total realized/unrealized gains (losses) included in Net earnings (loss)	23	(12)	54	(8)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	14	(3)	19	11
Purchases and issuances	97	62	276	191
Sales and settlements	(53)	(20)	(85)	(92)
Transfer into Level 3	8	5	8	42
Transfer out of Level 3	0	(38)	(31)	(92)
Financial assets, Ending Balance	1,471	1,154	1,471	1,154
Fixed maturities:
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	756	701	736	664
Total realized/unrealized gains (losses) included in Net earnings (loss)	5	(15)	3	(16)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	14	(3)	19	11
Purchases and issuances	42	39	114	105
Sales and settlements	(10)	(16)	(34)	(63)
Transfer into Level 3	8	5	8	42
Transfer out of Level 3	0	(21)	(31)	(53)
Financial assets, Ending Balance	815	690	815	690
U.S. government agency
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	0	0	0	0
Total realized/unrealized gains (losses) included in Net earnings (loss)	0	0	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0	0
Purchases and issuances	0	0	0	0
Sales and settlements	0	0	0	0
Transfer into Level 3	0	0	0	0
Transfer out of Level 3	0	0	0	0
Financial assets, Ending Balance	0	0	0	0
State and municipal
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	2	5	2	5
Total realized/unrealized gains (losses) included in Net earnings (loss)	0	0	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0	0
Purchases and issuances	0	0	0	0
Sales and settlements	0	(1)	0	(1)
Transfer into Level 3	0	0	0	0
Transfer out of Level 3	0	(2)	0	(2)
Financial assets, Ending Balance	2	2	2	2
Residential MBS
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	2	5	2	9
Total realized/unrealized gains (losses) included in Net earnings (loss)	0	0	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0	0
Purchases and issuances	0	0	0	0
Sales and settlements	0	0	0	(3)
Transfer into Level 3	0	0	0	4
Transfer out of Level 3	0	0	0	(5)
Financial assets, Ending Balance	2	5	2	5
Commercial MBS
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	0	0	0	0
Total realized/unrealized gains (losses) included in Net earnings (loss)	0	0	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0	0
Purchases and issuances	0	0	0	0
Sales and settlements	0	0	0	0
Transfer into Level 3	0	0	0	0
Transfer out of Level 3	0	0	0	0
Financial assets, Ending Balance	0	0	0	0
Collateralized loan obligations
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	1	1	1	2
Total realized/unrealized gains (losses) included in Net earnings (loss)	(1)	(1)	(1)	(1)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	1	0	1
Purchases and issuances	0	0	0	0
Sales and settlements	0	0	0	0
Transfer into Level 3	0	0	0	0
Transfer out of Level 3	0	0	0	(1)
Financial assets, Ending Balance	0	1	0	1
Other asset-backed securities
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	340	321	351	329
Total realized/unrealized gains (losses) included in Net earnings (loss)	0	0	(1)	(2)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	7	(4)	11	0
Purchases and issuances	16	28	40	38
Sales and settlements	(5)	(3)	(17)	(34)
Transfer into Level 3	5	0	5	31
Transfer out of Level 3	0	(12)	(26)	(32)
Financial assets, Ending Balance	363	330	363	330
Corporate and other
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	411	369	380	319
Total realized/unrealized gains (losses) included in Net earnings (loss)	6	(14)	5	(13)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	7	0	8	10
Purchases and issuances	26	11	74	67
Sales and settlements	(5)	(12)	(17)	(25)
Transfer into Level 3	3	5	3	7
Transfer out of Level 3	0	(7)	(5)	(13)
Financial assets, Ending Balance	448	352	448	352
Trading fixed maturities
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	12		0
Total realized/unrealized gains (losses) included in Net earnings (loss)	1		1
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0		0
Purchases and issuances	12		24
Sales and settlements	0		0
Transfer into Level 3	0		0
Transfer out of Level 3	0		0
Financial assets, Ending Balance	25		25
Equity securities
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	602	448	485	427
Total realized/unrealized gains (losses) included in Net earnings (loss)	18	4	53	11
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0	0
Purchases and issuances	43	23	133	84
Sales and settlements	(43)	(4)	(51)	(29)
Transfer into Level 3	0	0	0	0
Transfer out of Level 3	0	(17)	0	(39)
Financial assets, Ending Balance	620	454	620	454
Assets of MIE
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	12	11	9	11
Total realized/unrealized gains (losses) included in Net earnings (loss)	(1)	(1)	(3)	(3)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0	0
Purchases and issuances	0	0	5	2
Sales and settlements	0	0	0	0
Transfer into Level 3	0	0	0	0
Transfer out of Level 3	0	0	0	0
Financial assets, Ending Balance	$ 11	$ 10	$ 11	$ 10