Accounts Payable, Accrued Expenses and Other (Detail) - Truck, Parts and Other - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accounts Payable and Accrued Liabilities [Line Items]
Accounts payable	$ 1,154.7	$ 938.6
Product support liabilities	372.1	344.2
Accrued expenses	401.4	233.1
Accrued capital expenditures	120.1	111.2
Salaries and wages	238.9	194.8
Other	282.3	212.2
Accounts payable, accrued expenses and other	$ 2,569.5	$ 2,034.1