v3.26.1
Fair value of financial instruments - Fixed Rate Debt (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
2027 Senior Unsecured Notes    
Debt Instrument [Line Items]    
Carrying value $ 600.0 $ 600.0
2027 Senior Unsecured Notes | Level 3    
Debt Instrument [Line Items]    
Fair value 571.5 579.0
2029 Senior Unsecured Notes    
Debt Instrument [Line Items]    
Carrying value 400.0 400.0
2029 Senior Unsecured Notes | Level 3    
Debt Instrument [Line Items]    
Fair value 405.8 412.2
2032 Senior Unsecured Notes    
Debt Instrument [Line Items]    
Carrying value 400.0 400.0
2032 Senior Unsecured Notes | Level 3    
Debt Instrument [Line Items]    
Fair value $ 402.9 $ 416.0