Insurance Company Subsidiary Operations - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($) Reinsurer	Dec. 31, 2024 USD ($)	Sep. 30, 2025
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Ceded unpaid loss	$ 167	$ 1,525
Prepaid reinsurance premiums	980	520
Increase (decrease) in loss and loss adjustment expense reserve	0	0
Unearned premiums	1,053	577
Total assets	29,991	17,612
Variable Interest Entities ("VIEs")
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Total assets	1,153
Total Liabilities	$ 1,151
Wright National Flood Insurance Company
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Ceded rate of premiums under insurance program	100.00%
Prepaid reinsurance premiums	$ 553	520
Reserve for losses and loss adjustment expense	$ 167	1,525
Number of reinsurers | Reinsurer	2
Expenses and allowance rate received in premiums	28.40%		29.10%
Premiums written net	$ 1,078	1,005
Ceded to highly rated carriers for excess flood policies	3	4
Wright National Flood Insurance Company | FEMA
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Premiums written net	1,075	1,001
Captive Insurance Facility
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Prepaid reinsurance premiums	426
Deferred acquisitions costs	12	12
Reinsurance payable	301	5
Reserve for losses and loss adjustment expense	501	14
Unearned premiums	499	57
Premiums written net	$ 751	$ 74