Income taxes - Components of Comprehensive Provision for Income Taxes Allocation (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule Of Income Tax [Line Items]
United States	$ 81.4	$ 131.4	$ 45.2
Non-U.S. subsidiaries	88.5	126.4	55.4
Income from continuing operations before income taxes	169.9	257.8	100.6
Expected tax expense, at U.S. federal statutory income tax rate of 21%	35.7	54.1	21.1
Non-U.S. tax rates	2.0	4.5	0.5
Incremental net tax benefit on earnings and losses of U.S. and non-U.S. tax group companies	(1.7)	(2.0)	(8.7)
Valuation allowance	(3.0)	0.9	3.8
Global intangible low-tax income, net	1.8	2.8	2.2
Tax rate changes			(0.2)
U.S. state income taxes and other, net	1.5	1.5	0.9
Adjustment to the reserve for uncertain tax positions, net	(2.9)	(2.6)	(3.8)
Nondeductible expenses	1.0	1.1	1.0
Other, net	(0.6)	(0.2)	(0.9)
Income tax expense	33.8	60.1	15.9
Comprehensive provision for income taxes allocable to:
Net income	33.8	60.1	15.9
Other comprehensive income (loss):
Discontinued operations			0.6
Currency translation	(3.3)	(0.8)	1.6
Total	92.1	89.0	10.4
Valuation allowance 163(j) carryforward	(2.9)
OPEB
Other comprehensive income (loss):
Defined benefit plans	0.9		(0.4)
Pension Plans
Other comprehensive income (loss):
Defined benefit plans	$ 60.7	$ 29.7	$ (7.3)