Variable Interest Entities - Assets and liabilities of consolidated VIEs (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Investments
Fixed income securities, at fair value	$ 40,745	$ 42,136
Short-term investments, at fair value	4,344	4,009
Deferred policy acquisition costs	4,824	4,722
Premium installment receivables, net	8,874	8,364
Reinsurance and indemnification recoverables, net	9,691	10,024
Other assets, net	6,059	6,086
Total assets	97,150	99,440
Liabilities
Reserve for property and casualty insurance claims and claims expense	32,991	33,060
Unearned premiums	20,248	19,844
Total liabilities	74,012	74,313
Variable Interest Entity, Primary Beneficiary
Investments
Fixed income securities, at fair value	324	324
Short-term investments, at fair value	16	30
Deferred policy acquisition costs	16	15
Premium installment receivables, net	44	42
Reinsurance and indemnification recoverables, net	101	114
Other assets, net	66	82
Total assets	567	607
Liabilities
Reserve for property and casualty insurance claims and claims expense	225	226
Unearned premiums	165	175
Other liabilities and expenses	258	265
Total liabilities	$ 648	$ 666