Finance and Other Receivables (Detail) - USD ($) $ in Millions		Sep. 30, 2020		Jan. 01, 2020	Dec. 31, 2019		Sep. 30, 2019	Dec. 31, 2018
Financial Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		$ 5,518.6			$ 5,241.7
Finance leases		3,695.0			3,906.7
Dealer wholesale financing		2,079.7			2,907.4
Operating lease receivables and other		155.9			142.6
Finance and other receivables, net of deferred income		11,449.2			12,198.4
Less allowance for losses		(124.7)	[1]		(118.6)	[1]	$ (114.9)	$ (113.8)
Finance and other receivables, net		11,324.5		$ 12,079.8	12,086.0	[2]
Loans and Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses		(117.8)			(104.4)
Dealer | Wholesale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses		(3.2)			(4.3)
Dealer | Wholesale | Financial Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses		(3.2)			(4.3)		(6.4)	(6.8)
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses		(3.7)			(3.7)
Other | Financial Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses	[3]	$ (3.7)			$ (3.7)		$ (3.5)	$ (3.2)

[1] The beginning balance has been adjusted for the adoption of ASU 2016-13.

[2] The December 31, 2019 consolidated balance sheet has been derived from audited financial statements.

[3] Operating leases and other trade receivables.