Income taxes - Additional Information (Detail) - USD ($) $ in Millions		1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 27, 2020	Mar. 31, 2020	Dec. 31, 2017	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2018
Income Taxes Disclosure [Line Items]
Income tax expense				$ 33.8	$ 60.1	$ 15.9
Business interest income, adjusted taxable income	30.00%			30.00%
Current income taxes expense (benefit)				$ 36.4	51.2	28.2
Deferred income taxes expense (benefit)				(2.6)	8.9	(12.3)
Deferred income tax benefit from change in enacted tax rate						(0.2)
Deferred income taxes				63.5	46.2
CARES act of 2020, Business interest income, adjusted taxable income	50.00%
Cash tax benefit recognized		$ 1.0
Unrecognized tax benefits impact on effective tax rate				3.5
Increase (decrease) in unrecognized tax benefits				1.2
Accrued interest and penalties during the period				0.2	0.7	0.8
Accrued interest and penalties end of the period				0.1	0.9
Contran
Income Taxes Disclosure [Line Items]
Income taxes payable current				5.8	1.5
Income taxes payable noncurrent				$ 33.4	44.5
European Subsidiaries | Chemicals | Transition Tax
Income Taxes Disclosure [Line Items]
Current income tax expense provisional pursuant to transition tax			$ 74.1
Income tax liability payable period				8 years			8 years
Payable to affiliate				$ 44.5
European Subsidiaries | Chemicals | Transition Tax | Contran
Income Taxes Disclosure [Line Items]
Income taxes payable current				11.1
Income taxes payable noncurrent				33.4
European Subsidiaries | Chemicals | Income Taxes Payables [Member] | Transition Tax | Contran
Income Taxes Disclosure [Line Items]
Current income tax expense payable in increments over remainder of eight year period				44.5
Corporate Tax Purposes | Kronos | Germany | Chemicals
Income Taxes Disclosure [Line Items]
Net operating loss carryforwards				414.0
Corporate Tax Purposes | Kronos | Belgium | Chemicals
Income Taxes Disclosure [Line Items]
Net operating loss carryforwards				13.0
Direct Investment in Subsidiary | Kronos
Income Taxes Disclosure [Line Items]
Deferred income taxes expense (benefit)				1.2	$ (5.0)	$ 2.4
Deferred income taxes				55.0
Direct Investment in Subsidiary | Kronos | Maximum [Member]
Income Taxes Disclosure [Line Items]
Deferred income taxes				$ 155.4