Estimated Value of Returned Goods Assets and Related Return Liabilities (Detail) - Truck, Parts and Other - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Trucks
Entity Wide Information Revenue From External Customer [Line Items]
Other current assets	$ 101.5	$ 116.7
Accounts payable, accrued expenses and other	105.9	121.7
Other noncurrent assets, net	171.2	135.9
Other liabilities	179.3	144.7
Assets	272.7	252.6
Liabilities	285.2	266.4
Parts Subsegment
Entity Wide Information Revenue From External Customer [Line Items]
Other current assets	103.3	101.7
Accounts payable, accrued expenses and other	250.6	244.4
Assets	103.3	101.7
Liabilities	$ 250.6	$ 244.4