Estimated Value of Returned Goods Assets and Related Return Liabilities (Detail) - Truck, Parts and Other - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Trucks
Entity Wide Information Revenue From External Customer [Line Items]
Other current assets	$ 125.4	$ 147.3
Accounts payable, accrued expenses and other	129.5	149.5
Other noncurrent assets, net	164.3	186.7
Other liabilities	173.5	196.4
Assets	289.7	334.0
Liabilities	303.0	345.9
Parts Subsegment
Entity Wide Information Revenue From External Customer [Line Items]
Accounts payable, accrued expenses and other	228.3	216.3
Other noncurrent assets, net	92.7	86.8
Assets	92.7	86.8
Liabilities	$ 228.3	$ 216.3