Leases - Summary of Location and Amount of Lease Expense (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Finance lease expense
Total lease expense	$ 9.1	$ 17.9
Warehousing, Delivery, Selling, General, and Administrative [Member]
Lessee Lease Description [Line Items]
Operating lease expense	5.5	11.1
Finance lease expense
Amortization of lease assets	1.8	3.4
Variable lease expense	0.7	1.4
Short-term lease expense	0.6	1.1
Interest and Other Expense on Debt [Member]
Finance lease expense
Interest on lease liabilities	$ 0.5	$ 0.9