Acquisitions (Schedule of recognized identifiable assets acquired and liabilities assumed) (Details) - USD ($) $ in Millions		Jun. 30, 2024	Dec. 31, 2023	Jul. 01, 2023	Jun. 30, 2023	Dec. 31, 2022
Business Acquisition [Line Items]
Accrued investment income		$ 1,130	$ 1,086
Insurance and reinsurance balances receivable		15,929	13,379
Reinsurance recoverable on losses and loss expenses	[1]	19,355	19,952
Reinsurance recoverable on policy benefits	[1]	291	280
Value of business acquired		3,434	3,674
Other Assets		7,684	7,508
Total assets		238,551	230,682
Unpaid losses and loss expenses		82,191	80,122		$ 76,480	$ 75,747
Unearned premiums		24,102	22,051
Future policy benefits		14,663	13,888		11,064
Policyholders' account balances		7,787	7,462		3,215
Insurance and reinsurance balances payable		9,126	8,302
Accounts Payable and Accrued Liabilities		8,047	8,332
Deferred tax liabilities		1,572	1,555
Repurchase agreements		3,149	2,833
Total liabilities		173,976	166,991
Stockholders' Equity		61,038	59,507		52,875
Noncontrolling interests		3,537	4,184
Total shareholders' equity		$ 64,575	$ 63,691		$ 52,875
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.