Income Taxes - Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Accrued liabilities and reserves	$ 59.4	$ 41.9
Pension and other post-retirement compensation and benefits	26.2	25.2
Employee compensation and benefits	18.5	19.6
Tax loss and credit carryforwards	744.5	712.0
Interest limitations	49.9	45.0
Total deferred tax assets	898.5	843.7
Valuation allowance	747.3	693.8
Deferred tax assets, net of valuation allowance	151.2	149.9
Deferred tax liabilities
Property, plant and equipment	5.3	8.5
Goodwill and other intangibles	209.0	200.4
Other liabilities	16.9	15.8
Deferred Tax Liabilities, Gross	231.2	224.7
Total deferred tax liabilities	$ 80.0	$ 74.8