Balance Sheet Classifications, Fair Value, Gross and Pro Forma Net Amounts of Derivative Financial Instruments (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
ASSETS
Derivative assets	$ 213.9	$ 56.3
Pro forma net amount	195.7	47.3
LIABILITIES
Derivative liabilities	67.7	44.3
Pro forma net amount	49.5	35.3
Interest-Rate Contracts \| Financial Services
ASSETS
Less amounts not offset in financial instruments	(9.7)	(8.6)
LIABILITIES
Less amounts not offset in financial instruments	(9.7)	(8.6)
Foreign-exchange contracts \| Truck, Parts and Other
ASSETS
Less amounts not offset in financial instruments	(8.5)	(0.4)
LIABILITIES
Less amounts not offset in financial instruments	(8.5)	(0.4)
Foreign-exchange contracts \| Truck, Parts and Other \| Accounts payable, accrued expenses and other
LIABILITIES
Derivative liabilities	5.4	1.8
Designated under hedge accounting
ASSETS
Derivative assets	186.7	55.9
LIABILITIES
Derivative liabilities	62.2	40.2
Designated under hedge accounting \| Interest-Rate Contracts \| Financial Services \| Other Assets
ASSETS
Derivative assets	113.1	45.8
Designated under hedge accounting \| Interest-Rate Contracts \| Financial Services \| Deferred Taxes And Other Liabilities
LIABILITIES
Derivative liabilities	53.3	31.0
Designated under hedge accounting \| Foreign-exchange contracts \| Truck, Parts and Other \| Other current assets
ASSETS
Derivative assets	73.6	10.1
Designated under hedge accounting \| Foreign-exchange contracts \| Truck, Parts and Other \| Accounts payable, accrued expenses and other
LIABILITIES
Derivative liabilities	8.9	9.2
Not designated as hedging instruments
ASSETS
Derivative assets	27.2	0.4
LIABILITIES
Derivative liabilities	5.5	4.1
Not designated as hedging instruments \| Foreign-exchange contracts \| Financial Services \| Other Assets
ASSETS
Derivative assets	5.1
Not designated as hedging instruments \| Foreign-exchange contracts \| Financial Services \| Deferred Taxes And Other Liabilities
LIABILITIES
Derivative liabilities	0.1	2.3
Not designated as hedging instruments \| Foreign-exchange contracts \| Truck, Parts and Other \| Other current assets
ASSETS
Derivative assets	$ 22.1	$ 0.4

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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