Finance and Other Receivables (Detail) (Financial Services, USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012		Mar. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 3,735.3	$ 3,738.2
Retail direct financing leases	2,473.4	2,489.3
Sales-type finance leases	888.8	916.8
Dealer wholesale financing	1,526.0	1,541.0
Operating lease and other trade receivables	116.3	112.0
Unearned interest: Finance leases	(357.7)	(369.0)
Loans and Leases Receivable, Net of Deferred Income, Total	8,382.1	8,428.3
Less allowance for losses	(132.9)	(130.0)		(141.3)	(139.0)
Finance and other receivables, net	8,249.2	8,298.3	[1]
Loans and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses	(114.4)	(112.6)
Dealer wholesale financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses	(11.8)	(11.8)		(14.6)	(11.7)
Operating lease and other trade receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses	$ (6.7)	$ (5.6)

[1] The December 31, 2012 consolidated balance sheet has been derived from audited financial statements.