Variable Interest Entities - Assets and liabilities of consolidated VIEs (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Investments
Fixed income securities	$ 44,103	$ 42,485
Short-term investments	6,722	4,173
Deferred policy acquisition costs	5,471	5,442	$ 4,843
Premium installment and other receivables, net	9,483	9,165
Reinsurance recoverables, net	9,528	9,619
Other assets	5,758	5,904
Total assets	99,631	97,989
Liabilities
Reserve for property and casualty insurance claims and claims expense	38,644	37,541
Unearned premiums	22,499	22,299
Total liabilities	82,258	80,626
Variable Interest Entity, Primary Beneficiary
Investments
Fixed income securities	285	302
Short-term investments	16	13
Deferred policy acquisition costs	23	15
Premium installment and other receivables, net	36	43
Reinsurance recoverables, net	88	97
Other assets	37	90
Total assets	485	560
Liabilities
Reserve for property and casualty insurance claims and claims expense	194	209
Unearned premiums	132	171
Other liabilities and expenses	285	311
Total liabilities	$ 611	$ 691