Variable Interest Entities - Assets and liabilities of consolidated VIEs (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Investments
Fixed income securities	$ 45,550	$ 42,485
Short-term investments	5,137	4,173
Deferred policy acquisition costs	5,607	5,442	$ 5,049
Premium installment and other receivables, net	9,713	9,165
Reinsurance recoverables, net	9,151	9,619
Other assets	6,278	5,904
Total assets	100,514	97,989
Liabilities
Reserve for property and casualty insurance claims and claims expense	40,531	37,541
Unearned premiums	23,355	22,299
Total liabilities	85,142	80,626
Variable Interest Entity, Primary Beneficiary
Investments
Fixed income securities	269	302
Short-term investments	18	13
Deferred policy acquisition costs	17	15
Premium installment and other receivables, net	42	43
Reinsurance recoverables, net	83	97
Other assets	27	90
Total assets	456	560
Liabilities
Reserve for property and casualty insurance claims and claims expense	194	209
Unearned premiums	132	171
Other liabilities and expenses	280	311
Total liabilities	$ 606	$ 691