Equipment on Operating Leases, net - Additional Information (Detail) (USD $)	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ 207,981,000	$ 193,447,000
Depreciation expense	42,371,000	38,293,000	37,511,000
Revenue associated with equipment hiring arrangements	23,400,000	18,700,000	18,400,000
Property Subject to Operating Lease
Property, Plant and Equipment [Line Items]
Accumulated depreciation	100,200,000	94,800,000
Depreciation expense	$ 13,600,000	$ 12,900,000	$ 12,400,000