Finance and Other Receivables (Detail) - USD ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financial Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		$ 4,147.8	$ 3,948.6
Direct financing leases		3,211.7	2,798.0
Sales-type finance leases		781.1	867.3
Dealer wholesale financing		1,880.6	1,528.5
Operating lease receivables and other		161.1	150.9
Unearned interest: Finance leases		(368.0)	(344.7)
Finance and other receivables, net of deferred income		9,814.3	8,948.6
Less allowance for losses		(117.2)	(111.2)	$ (114.8)	$ (122.0)
Finance and other receivables, net		9,697.1	8,837.4
Loans And Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses		(101.9)	(97.1)
Dealer | Wholesale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses		(6.0)	(5.5)
Dealer | Wholesale | Financial Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses		(6.0)	(5.5)	(7.3)	(9.0)
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses		(9.3)	(8.6)
Other | Financial Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses	[1]	$ (9.3)	$ (8.6)	$ (8.3)	$ (7.5)

[1] Operating lease and other trade receivables.