Other assets - Components (Details) - USD ($) $ in Millions |
Dec. 31, 2025 |
Dec. 31, 2024 |
|---|---|---|
| Other assets: | ||
| Note receivables - OPA | $ 116.1 | $ 91.6 |
| Operating lease right-of-use assets | $ 19.9 | $ 20.6 |
| Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] | Total | Total |
| IBNR receivables | $ 14.8 | $ 15.0 |
| Land held for development | 7.4 | |
| Restricted cash and cash equivalents | $ 6.1 | $ 5.5 |
| Restricted Cash and Cash Equivalent, Noncurrent, Statement of Financial Position [Extensible Enumeration] | Total | Total |
| Other | $ 20.7 | $ 21.4 |
| Total | $ 177.6 | $ 161.5 |
| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition Amortized cost, before allowance for credit loss, of financing receivable classified as noncurrent. Excludes net investment in lease. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount of lessee's right to use underlying asset under operating lease. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Indicates line item in statement of financial position that includes operating lease right-of-use asset. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of other miscellaneous assets expected to be realized or consumed after one year or normal operating cycle, if longer. No definition available.
|
| X | ||||||||||
- Definition Amount of noncurrent assets classified as other. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Estimated amount after valuation allowance of reinsurance recoverables, due from reinsurers for incurred claims not yet reported, and claims settlement expenses. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount of cash and cash equivalent restricted as to withdrawal or usage, classified as noncurrent. Cash includes, but is not limited to, currency on hand, demand deposit with financial institution, and account with general characteristic of demand deposit. Cash equivalent includes, but is not limited to, short-term, highly liquid investment that is both readily convertible to known amount of cash and so near maturity that it presents insignificant risk of change in value because of change in interest rate. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Indicates line item in statement of financial position that includes cash and cash equivalent restricted to withdrawal or usage, classified as noncurrent. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Land held for development noncurrent. No definition available.
|