Location and Amount of Loss (Gain) for the Cash Flow and Fair Value Hedges Reclassified from AOCI into Income (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Interest-Rate Contracts
Derivative [Line Items]
Reclassification from AOCI into income	$ 6,700,000	$ 9,300,000
Foreign-exchange contracts
Derivative [Line Items]
Reclassification from AOCI into income	7,800,000	2,500,000
Cash Flow Hedging
Derivative [Line Items]
Reclassification from AOCI into income	0	0
Cash Flow Hedging | Interest-Rate Contracts | Financial Services | Interest and other borrowing expenses
Derivative [Line Items]
Reclassification from AOCI into income	6,700,000	9,300,000
Cash Flow Hedging | Foreign-exchange contracts | Truck, Parts and Other | Sales
Derivative [Line Items]
Reclassification from AOCI into income	9,400,000	4,600,000
Cash Flow Hedging | Foreign-exchange contracts | Truck, Parts and Other | Cost of sales and revenues
Derivative [Line Items]
Reclassification from AOCI into income	(2,100,000)	(1,100,000)
Cash Flow Hedging | Foreign-exchange contracts | Truck, Parts and Other | Interest and other (income), net
Derivative [Line Items]
Reclassification from AOCI into income	$ 500,000	$ (1,000,000.0)