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Debt - Other Operations Debt (Details) $ in Millions	Jun. 30, 2026 USD ($) credit_facility	Dec. 31, 2025 USD ($)	Jul. 16, 2025 USD ($)
Other Operations Debt \| Secured Debt
Debt Instrument
Amount borrowed	$ 18.3	$ 19.1
Secured credit facilities \| credit_facility	4
WTM Credit Facility \| Revolving Credit Facility
Debt Instrument
Total commitment under revolving credit facility			$ 250.0
WTM Credit Facility \| Revolving Credit Facility \| Minimum
Debt Instrument
Stated margin			1.10%
WTM Credit Facility \| Revolving Credit Facility \| Maximum
Debt Instrument
Stated margin			1.50%