Finance and Other Receivables (Detail) (Financial Services, USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 3,233.0	$ 3,114.8
Retail direct financing leases	2,270.2	2,187.8
Sales-type finance leases	796.4	795.8
Dealer wholesale financing	1,805.9	1,517.1
Interest and other receivables	109.5	111.0
Unearned interest on finance leases	(339.1)	(327.8)
Loans and Leases Receivable, Net of Deferred Income, Total	7,875.9	7,398.7
Finance and other receivables, net	7,734.6	7,259.7
Loans, leases and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses	(126.7)	(127.3)
Dealer wholesale financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses	$ (14.6)	$ (11.7)