Variable Interest Entities - Assets and liabilities of consolidated VIEs (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Investments
Fixed income securities	$ 42,485	$ 42,136
Short-term investments	4,173	4,009
Deferred policy acquisition costs	5,418	4,722	$ 3,774	$ 3,600
Premium installment and other receivables, net	9,165	8,364
Reinsurance recoverables, net	9,606	10,024
Other assets	5,905	6,086
Total assets	97,957	99,440
Liabilities
Reserve for property and casualty insurance claims and claims expense	37,541	33,060
Unearned premiums	22,311	19,844
Total liabilities	80,607	74,313
Variable Interest Entity, Primary Beneficiary
Investments
Fixed income securities	302	324
Short-term investments	13	30
Deferred policy acquisition costs	15	15
Premium installment and other receivables, net	43	42
Reinsurance recoverables, net	97	114
Other assets	90	82
Total assets	560	607
Liabilities
Reserve for property and casualty insurance claims and claims expense	209	226
Unearned premiums	171	175
Other liabilities and accrued expenses	311	265
Total liabilities	$ 691	$ 666