Schedule VI. Supplemental Information Concerning Property and Casualty Insurance Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Incurred claim and claim adjustment expenses related to current year	$ 6,330	$ 5,667	$ 5,181
Incurred claim and claim adjustment expenses related to prior years	42	48	(32)
Consolidated Property and Casualty Insurance Entity
Deferred acquisition costs		896
Reserves for unpaid claim and claim adjustment expenses	24,976	23,304
Discount deducted from claim and claim adjustment expense reserves above (based on interest rates ranging from 3.5% to 6.6%)	615	647
Unearned premiums	7,346	6,933
Net written premiums	10,605	9,892	9,128
Net earned premiums	10,211	9,480	8,667
Net investment income	2,396	2,163	1,751
Incurred claim and claim adjustment expenses related to current year		5,667	5,181
Incurred claim and claim adjustment expenses related to prior years		48	(32)
Amortization of deferred acquisition costs	1,798	1,644	1,490
Paid claim and claim adjustment expenses	$ 5,189	$ 4,601	$ 4,302
Consolidated Property and Casualty Insurance Entity | Minimum
Supplemental Information Parenthetical
SEC Schedule, 12-18, supplemental information, property-casualty insurance underwriters, interest rate at which discount computed	3.50%	3.50%	3.50%
Consolidated Property and Casualty Insurance Entity | Maximum
Supplemental Information Parenthetical
SEC Schedule, 12-18, supplemental information, property-casualty insurance underwriters, interest rate at which discount computed	6.60%	6.60%	6.60%