Leases - Schedule of Lease Assets and Liabilities Included on Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Operating Leases:
Operating lease right-of-use assets	$ 33.9	$ 40.9	$ 37.6
Current maturities of operating lease right-of-use assets	9.1	9.7
Operating lease right-of-use liabilities, less current maturities	24.9	31.6
Total operating lease liabilities	34.0	41.3	$ 38.0
Finance Leases:
Gross property, plant and equipment	11.1	10.6
Accumulated depreciation	(6.3)	(5.2)
Property, plant and equipment, net	$ 4.8	$ 5.4
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentNet	us-gaap:PropertyPlantAndEquipmentNet
Current maturities of long-term lease liabilities	$ 1.4	$ 1.4
Long-term lease liabilities, less current maturities	1.9	2.8
Total finance lease liabilities	$ 3.3	$ 4.2