Claim and Claim Adjustment Expense Reserves (Reconciliation of Claim and Claim Adjustment Expense Reserves) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Reserves, beginning of year:
Gross	$ 24,976	$ 23,304	$ 22,120
Ceded	5,713	5,141	5,191
Net reserves, beginning of year	19,263	18,163	16,929
Net incurred claim and claim adjustment expenses:
Provision for insured events of current year	6,724	6,330	5,667
Increase (decrease) in provision for insured events of prior years	189	42	48
Amortization of discount	39	39	44
Total net incurred	6,952	6,411	5,759
Net payments attributable to:
Current year events	(1,089)	(1,093)	(922)
Prior year events	(4,685)	(4,096)	(3,679)
Total net payments	(5,774)	(5,189)	(4,601)
Foreign currency translation adjustment and other	176	(122)	76
Net reserves, end of year	20,617	19,263	18,163
Ceded reserves, end of year	5,982	5,713	5,141
Gross reserves, end of year	$ 26,599	$ 24,976	$ 23,304