Nature of Operations - Additional Information (Detail)	12 Months Ended
	Aug. 31, 2017 Vehicle Segment
Organization and Nature of Operations [Line Items]
Number of reportable segments | Segment	4
Leasing & Services
Organization and Nature of Operations [Line Items]
Number of railcars owned	8,300
Number of railcars that get services	336,000
Leasing & Services | Equipment on operating leases, net
Organization and Nature of Operations [Line Items]
Number of railcars owned	7,200
Leasing & Services | Leased railcars for syndication
Organization and Nature of Operations [Line Items]
Number of railcars owned	1,000
Leasing & Services | Inventory Finished Goods
Organization and Nature of Operations [Line Items]
Number of railcars owned	100