Variable Interest Entities - Schedule of Assets and Liabilities of Reciprocal Exchanges (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Assets
Fixed income securities, at fair value	$ 51,993	$ 52,747
Short-term investments	6,541	4,537
Premium installment and other receivables, net	11,053	10,614
Reinsurance recoverables, net	10,091	8,924
Other assets	4,964	5,140
Total assets	115,161	111,617
Liabilities
Reserve for property and casualty insurance claims and claims expense	43,835	41,917
Unearned premiums	27,167	26,909
Total liabilities	93,109	90,250
Variable Interest Entity, Primary Beneficiary
Assets
Fixed income securities, at fair value	3	47
Short-term investments	105	112
Premium installment and other receivables, net	1	9
Reinsurance recoverables, net	40	76
Other assets	11	25
Total assets	160	269
Liabilities
Reserve for property and casualty insurance claims and claims expense	159	214
Unearned premiums	1	22
Other liabilities and expenses	197	235
Total liabilities	$ 357	$ 471