Reinsurance - Summary of Direct, Assumed and Ceded Premiums Earned (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Reinsurance Disclosures [Abstract]
Direct	$ 159,653	$ 139,479	$ 136,927
Assumed	5,100	4,753	5,988
Ceded	(114)	(66)	(61)
Net premiums	$ 164,639	$ 144,166	$ 142,854
Percentage—assumed to net premiums	3.10%	3.30%	4.20%