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Related party transactions - Additional Information (Details) € in Millions, shares in Millions, $ in Millions			1 Months Ended	12 Months Ended
	Feb. 12, 2024 USD ($)	Feb. 12, 2024 EUR (€)	Feb. 29, 2024 USD ($)	Dec. 31, 2025 USD ($) shares	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Related Party Transaction [Line Items]
Subordinated, Unsecured Term Loan from Contran					$ 53.7
Kronos \| Subordinated, unsecured term loan from Contran
Related Party Transaction [Line Items]
Subordinated, Unsecured Term Loan from Contran	$ 53.7	€ 50.0		$ 53.7
Contran \| Intercorporate Services Agreements Fees
Related Party Transaction [Line Items]
Related party transaction				42.6	39.5	$ 37.8
Contran \| Combined Information Technology Data Recovery Program
Related Party Transaction [Line Items]
Related party transaction				0.3	0.4	0.4
Contran \| Pledge Fee Received
Related Party Transaction [Line Items]
Revenue and other income from related party transactions				0.5	0.9	0.8
Contran \| Kronos \| Sublease Agreement
Related Party Transaction [Line Items]
Payment for sublease rent and related ancillary services				$ 0.7	0.7	0.6
Contran \| Kronos \| Stock Pledged as Collateral
Related Party Transaction [Line Items]
Stock pledged as collateral \| shares				16.7
Contran \| Contran Credit Facility
Related Party Transaction [Line Items]
Interest on borrowings and unused commitment fees under credit facilities				$ 3.4	6.3	10.3
Contran and Other Affiliates
Related Party Transaction [Line Items]
Related party transaction cash paid for insurance premium				$ 24.1	29.7	$ 29.3
Related Party [Member] \| Kronos \| Subordinated, unsecured term loan from Contran \| Contran
Related Party Transaction [Line Items]
Subordinated, Unsecured Term Loan from Contran			$ 53.7
Interest expense					$ 5.1