Fair Value Measurements - Changes in balances of Level 3 financial assets carried at fair value (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	$ 1,297	$ 1,128	$ 1,230	$ 1,102
Total realized/unrealized gains (losses) included in Net earnings (loss)	13	3	31	4
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	5	8	5	14
Purchases and issuances	87	45	179	129
Sales and settlements	(19)	(31)	(32)	(72)
Transfer into Level 3	0	33	0	37
Transfer out of Level 3	(1)	(26)	(31)	(54)
Financial assets, Ending Balance	1,382	1,160	1,382	1,160
Fixed maturities:
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	742	705	736	664
Total realized/unrealized gains (losses) included in Net earnings (loss)	(1)	(6)	(2)	(1)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	5	8	5	14
Purchases and issuances	24	15	72	66
Sales and settlements	(13)	(28)	(24)	(47)
Transfer into Level 3	0	33	0	37
Transfer out of Level 3	(1)	(26)	(31)	(32)
Financial assets, Ending Balance	756	701	756	701
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	0	0	0
Transfer into Level 3	0	0	0	0
Transfer out of Level 3	0	0	0	0
Financial assets, Ending Balance	2	5	2	5
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)	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	(1)
Financial assets, Ending Balance	1	1	1	1
Other asset-backed securities
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	335	335	351	329
Total realized/unrealized gains (losses) included in Net earnings (loss)	(1)	(2)	(1)	(2)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	4	0	4	4
Purchases and issuances	9	3	24	10
Sales and settlements	(7)	(26)	(12)	(31)
Transfer into Level 3	0	31	0	31
Transfer out of Level 3	0	(20)	(26)	(20)
Financial assets, Ending Balance	340	321	340	321
Corporate and other
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	402	359	380	319
Total realized/unrealized gains (losses) included in Net earnings (loss)	0	(4)	(1)	1
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	1	8	1	10
Purchases and issuances	15	12	48	56
Sales and settlements	(6)	(2)	(12)	(13)
Transfer into Level 3	0	2	0	2
Transfer out of Level 3	(1)	(6)	(5)	(6)
Financial assets, Ending Balance	411	369	411	369
Trading fixed maturities
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	0		0
Total realized/unrealized gains (losses) included in Net earnings (loss)	0		0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0		0
Purchases and issuances	12		12
Sales and settlements	0		0
Transfer into Level 3	0		0
Transfer out of Level 3	0		0
Financial assets, Ending Balance	12		12
Equity securities
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	545	411	485	427
Total realized/unrealized gains (losses) included in Net earnings (loss)	15	10	35	7
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0	0
Purchases and issuances	48	30	90	61
Sales and settlements	(6)	(3)	(8)	(25)
Transfer into Level 3	0	0	0	0
Transfer out of Level 3	0	0	0	(22)
Financial assets, Ending Balance	602	448	602	448
Assets of MIE
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	10	12	9	11
Total realized/unrealized gains (losses) included in Net earnings (loss)	(1)	(1)	(2)	(2)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0	0
Purchases and issuances	3	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	$ 12	$ 11	$ 12	$ 11