Debt Commitments - Debt Obligations and Letters of Credit Outstanding (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Debt Instrument [Line Items]
Total	$ 125.0	$ 125.0
Less: Current portion of debt	(25.0)	(25.0)
Long-term debt	$ 100.0	100.0
Credit Facility \| Unsecured Revolving Credit Facility
Debt Instrument [Line Items]
Average Interest Rate, weighted per annum	4.68%
Total	$ 0.0	0.0
Credit Facility \| Letter of Credit Subfacility
Debt Instrument [Line Items]
Outstanding letters of credit under unsecured revolving credit facility - contingent obligation	$ 0.2	29.7
Senior Unsecured Promissory Notes \| Senior unsecured promissory notes payable, Series E
Debt Instrument [Line Items]
Average Interest Rate, fixed per annum	2.72%
Total	$ 50.0	50.0
Senior Unsecured Promissory Notes \| Senior unsecured promissory notes payable, Series G
Debt Instrument [Line Items]
Average Interest Rate, fixed per annum	2.13%
Total	$ 25.0	25.0
Senior Unsecured Promissory Notes \| Senior unsecured promissory notes payable, Series H
Debt Instrument [Line Items]
Average Interest Rate, fixed per annum	2.50%
Total	$ 50.0	$ 50.0

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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