Leases and commitments - Components of Lease Expense (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Operating lease cost	$ 22.8	$ 26.0	$ 36.7
Finance lease cost
Amortization of right-of-use assets	0.1	0.2	1.2
Total finance lease cost	0.1	0.2	1.2
Short-term lease costs	0.5	0.7	0.7
Variable lease cost	12.7	10.3	11.6
Sublease income	(0.5)	(1.1)	(1.8)
Total lease cost	$ 35.6	$ 36.1	$ 48.4

Finance Lease, Cost

No definition available.

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- Definition

Finance Lease, Cost1 [Abstract]

+ References

No definition available.

+ Details

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- Definition

Amount of amortization expense attributable to right-of-use asset from finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 53
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479589/842-20-55-53

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-4

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-4

+ Details

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- Definition

Amount of lease cost recognized by lessee for lease contract.

+ References

+ Details

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- References

No definition available.

+ Details

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- Definition

Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

+ References

+ Details

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- Definition

Amount of short-term lease cost, excluding expense for lease with term of one month or less.

+ References

+ Details

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- Definition

Amount of sublease income excluding finance and operating lease expense.

+ References

+ Details

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- Definition

Amount of variable lease cost, excluded from lease liability, recognized when obligation for payment is incurred for finance and operating leases.

+ References

+ Details

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