Schedule V - Supplemental Information Concerning Property and Casualty Insurance Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Supplemental Information Concerning Property and Casualty Insurance Operations [Abstract]
Deferred acquisition costs	$ 959	$ 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	6,330	5,667	5,181
Incurred claim and claim adjustment expenses related to prior years	42	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
Minimum
Supplemental Information Concerning Property and Casualty Insurance Operations [Abstract]
Interest rate at which discount computed	3.50%	3.50%
Maximum
Supplemental Information Concerning Property and Casualty Insurance Operations [Abstract]
Interest rate at which discount computed	6.60%	6.60%