Reinsurance - Unsecured Reinsurance Recoverable by Reinsurer (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Ceded Credit Risk [Line Items]
Reinsurance recoverable	$ 153.4	$ 170.4
Ceded Credit Risk, Unsecured
Ceded Credit Risk [Line Items]
Reinsurance recoverable	103.9	173.3
Lloyd's Underwriter Syndicate no. 2791 MAP | Ceded Credit Risk, Unsecured
Ceded Credit Risk [Line Items]
Reinsurance recoverable	1.2	2.1
Lloyd's Underwriter Syndicate no. 1084 CSL | Ceded Credit Risk, Unsecured
Ceded Credit Risk [Line Items]
Reinsurance recoverable	0.7	1.1
Top Reinsurers | Ceded Credit Risk, Unsecured
Ceded Credit Risk [Line Items]
Reinsurance recoverable	103.7	172.9
Other reinsurers | Ceded Credit Risk, Unsecured
Ceded Credit Risk [Line Items]
Reinsurance recoverable	0.2	0.4
A+ | Hannover Rueck SE | Ceded Credit Risk, Unsecured
Ceded Credit Risk [Line Items]
Reinsurance recoverable	48.9	104.0
A+ | Swiss Reinsurance America Corporation | Ceded Credit Risk, Unsecured
Ceded Credit Risk [Line Items]
Reinsurance recoverable	13.2	26.3
A+ | Aviva Insurance Limited | Ceded Credit Risk, Unsecured
Ceded Credit Risk [Line Items]
Reinsurance recoverable	8.9	2.7
A+ | Odyssey Reinsurance Company | Ceded Credit Risk, Unsecured
Ceded Credit Risk [Line Items]
Reinsurance recoverable	0.1	0.2
A+ | Lloyd's Underwriter Syndicate No. 2001 AML | Ceded Credit Risk, Unsecured
Ceded Credit Risk [Line Items]
Reinsurance recoverable	0.1	0.2
A | MAPFRE Re, Compania De Reaseguros S.A. | Ceded Credit Risk, Unsecured
Ceded Credit Risk [Line Items]
Reinsurance recoverable	29.3	34.0
A++ | Tokio Marine & Nichido Fire Insurance Company Limited | Ceded Credit Risk, Unsecured
Ceded Credit Risk [Line Items]
Reinsurance recoverable	1.2	1.9
A++ | The Travellers Indemnity Company | Ceded Credit Risk, Unsecured
Ceded Credit Risk [Line Items]
Reinsurance recoverable	$ 0.1	$ 0.4