Fair Value Measurements - Carrying Amount and Fair Values of the Company's Assets and Liabilities Measured on a Recurring Basis (Detail) - Recurring [Member] - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Carrying Amount [Member]
Non-derivatives:
Cash and cash equivalents	$ 147.1	$ 141.8
Non-derivatives:
Finance leases (including current portion)	0.0	0.1
Carrying Amount [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign Currency Forward Exchange Contracts [Member]
Derivatives (Level 1 measurement):
Foreign currency forward exchange contracts	0.5	1.2
Carrying Amount [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Emission Trading Scheme Credits [Member]
Derivatives (Level 1 measurement):
Emissions Trading Scheme credits	2.7	3.9
Carrying Amount [Member] | Significant Unobservable Inputs (Level 3) [Member]
Non-financial liabilities (Level 3 measurement):
Stock equivalent units	26.4	17.3
Fair Value [Member]
Non-derivatives:
Cash and cash equivalents	147.1	141.8
Non-derivatives:
Finance leases (including current portion)	0.0	0.1
Fair Value [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign Currency Forward Exchange Contracts [Member]
Derivatives (Level 1 measurement):
Foreign currency forward exchange contracts	0.5	1.2
Fair Value [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Emission Trading Scheme Credits [Member]
Derivatives (Level 1 measurement):
Emissions Trading Scheme credits	2.7	3.9
Fair Value [Member] | Significant Unobservable Inputs (Level 3) [Member]
Non-financial liabilities (Level 3 measurement):
Stock equivalent units	$ 26.4	$ 17.3