Acquisitions (Schedule of recognized identifiable assets acquired and liabilities assumed) (Details) - USD ($) $ in Millions		Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jul. 01, 2023	Dec. 31, 2022
Business Acquisition [Line Items]
Accrued investment income		$ 1,165	$ 1,086
Insurance and reinsurance balances receivable		15,709	13,379
Reinsurance recoverable on losses and loss expenses	[1]	19,606	19,952
Reinsurance recoverable on policy benefits	[1]	292	280
Value of business acquired		3,452	3,674
Other assets		8,461	7,508
Total assets		250,557	230,682
Unpaid losses and loss expenses		84,326	80,122	$ 79,705		$ 75,747
Unearned premiums		24,498	22,051
Future policy benefits		16,003	13,888	13,109
Policyholders' account balances		8,136	7,462	7,178
Insurance and reinsurance balances payable		8,696	8,302
Accounts Payable and Accrued Liabilities		8,967	8,332
Deferred tax liabilities		1,652	1,555
Repurchase agreements		3,048	2,833
Total liabilities		180,437	166,991
Stockholders' Equity		65,757	59,507	52,373
Noncontrolling interests		4,363	4,184
Total shareholders' equity		$ 70,120	$ 63,691	$ 57,504
Huatai Group
Business Acquisition [Line Items]
Investments and Cash					$ 13,346
Accrued investment income					60
Insurance and reinsurance balances receivable					277
Reinsurance recoverable on losses and loss expenses					581
Reinsurance recoverable on policy benefits					27
Value of business acquired					309
Goodwill and intangible assets					5,113
Other assets					748
Total assets					20,461
Unpaid losses and loss expenses					831
Unearned premiums					800
Future policy benefits					2,351
Policyholders' account balances					4,014
Insurance and reinsurance balances payable					644
Accounts Payable and Accrued Liabilities					682
Deferred tax liabilities					232
Repurchase agreements					1,269
Total liabilities					10,823
Stockholders' Equity					4,428
Noncontrolling interests					5,210
Total shareholders' equity					$ 9,638

[1] Net of valuation allowance for uncollectible reinsurance.