Finance and Other Receivables (Detail) (Financial Services, USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 3,554.8	$ 3,114.8
Retail direct financing leases	2,401.7	2,187.8
Sales-type finance leases	857.9	795.8
Dealer wholesale financing	1,702.4	1,517.1
Accrued rents and other trade receivables	111.5	111.0
Unearned interest on finance leases	(356.2)	(327.8)
Loans and Leases Receivable, Net of Deferred Income, Total	8,272.1	7,398.7
Finance and other receivables, net	8,133.0	7,259.7
Loans, leases and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses	(120.6)	(118.5)
Dealer wholesale financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses	(12.4)	(11.7)
Accrued rents and other trade receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less allowance for losses	$ (6.1)	$ (8.8)