Restructuring costs (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Apr. 30, 2024 USD ($)	Sep. 30, 2023 individual
Restructuring Cost and Reserve [Line Items]
Number of individuals impacted from workforce reductions | individual				100
Restructuring Charges	$ (0.1)
Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ 6.0
Sulfate Process Line at Plant in Varennes, Canada | 2nd Quarter of 2024
Restructuring Cost and Reserve [Line Items]
Cost of sales			$ 2.0
Sulfate Process Line at Plant in Varennes, Canada | 2nd and 3rd Quarter of 2024
Restructuring Cost and Reserve [Line Items]
Cost of sales			$ 15.0