Stockholders' equity - Tax Effects Related to Each Component of Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pretax	$ 23.9	$ 12.0	$ (19.8)
Tax Benefit (Expense)	(4.7)	(2.8)	4.4
Total other comprehensive income (loss), net of tax	19.2	9.2	(15.4)
Defined Benefit Pension Plan
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pretax	8.7	4.3	(5.0)
Tax Benefit (Expense)	(1.2)	(0.6)	0.7
Total other comprehensive income (loss), net of tax	7.5	3.7	(4.3)
Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pretax	14.6	8.9	(13.0)
Tax Benefit (Expense)	(3.9)	(2.4)	3.6
Total other comprehensive income (loss), net of tax	10.7	6.5	(9.4)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pretax	0.6	(1.2)	(1.8)
Tax Benefit (Expense)	0.4	0.2	0.1
Total other comprehensive income (loss), net of tax	$ 1.0	$ (1.0)	$ (1.7)