Leases - Schedule of Lease Assets and Liabilities Included on Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Operating Leases:
Operating lease right-of-use assets	$ 38.6	$ 40.9	$ 34.2
Current maturities of operating lease right-of-use assets	9.8	9.7	9.2
Operating lease right-of-use liabilities, less current maturities	29.0	31.6	25.5
Total operating lease liabilities	38.8	41.3	34.7
Finance Leases:
Gross property, plant and equipment	10.8	10.6	9.8
Accumulated depreciation	(5.7)	(5.2)	(4.6)
Property, plant and equipment, net	5.1	5.4	$ 5.2
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]			us-gaap:PropertyPlantAndEquipmentNet
Current maturities of long-term lease liabilities	1.4	1.4	$ 1.4
Long-term lease liabilities, less current maturities	2.3	2.8	2.8
Total finance lease liabilities	$ 3.7	$ 4.2	$ 4.2