Schedule VI. Supplemental Information Concerning Property and Casualty Insurance Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Line Items]
Incurred claim and claim adjustment expenses related to current year	$ 6,724	$ 6,330	$ 5,667
Incurred claim and claim adjustment expenses related to prior years	189	42	48
Consolidated Property and Casualty Insurance Entity
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Line Items]
Deferred acquisition costs		959	896
Reserves for unpaid claim and claim adjustment expenses	26,599	24,976	23,304
Discount deducted from claim and claim adjustment expense reserves above (based on interest rates ranging from 3.5% to 6.5%)	583	615	647
Unearned premiums		7,346	6,933
Net written premiums	11,101	10,605	9,892
Net earned premiums		10,211	9,480
Net investment income	2,467	2,396	2,163
Incurred claim and claim adjustment expenses related to current year		6,330	5,667
Incurred claim and claim adjustment expenses related to prior years		42	48
Amortization of deferred acquisition costs	1,898	1,798	1,644
Paid claim and claim adjustment expenses	$ 5,774	$ 5,189	$ 4,601
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	6.50%	6.50%	6.50%