Schedule of Balance Sheet Information Related to Leases (Detail) $ in Millions	Mar. 31, 2019 USD ($)
OPERATING LEASES
Total right-of-use assets	$ 42.4
Total lease liabilities	43.8
FINANCE LEASES
Total right-of-use assets	1.5
Total lease liabilities	1.7
Truck, Parts and Other
OPERATING LEASES
Accounts payable, accrued expenses and other	$ 12.9
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccountsPayableAndOtherAccruedLiabilitiesCurrent
Other liabilities	$ 25.4
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
FINANCE LEASES
Accounts payable, accrued expenses and other	$ 0.8
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccountsPayableAndOtherAccruedLiabilitiesCurrent
Other liabilities	$ 0.9
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
Truck, Parts and Other | Other Noncurrent Assets
OPERATING LEASES
Total right-of-use assets	$ 37.0
FINANCE LEASES
Total right-of-use assets	1.5
Financial Services | Other Assets
OPERATING LEASES
Total right-of-use assets	5.4
Financial Services | Accounts Payable, Accrued Expense and Other
OPERATING LEASES
Total lease liabilities	1.4
Financial Services | Deferred Taxes and Other Liabilities
OPERATING LEASES
Total lease liabilities	$ 4.1