Segment Information - Segments Internal Financial Reports (Detail) - USD ($) $ in Thousands	3 Months Ended
	Nov. 30, 2019	Nov. 30, 2018	Aug. 31, 2019
Segment Reporting Information [Line Items]
Revenues	$ 769,359	$ 604,523
Earnings (loss) from operations	41,784	36,454
Assets	2,948,776		$ 2,990,637
Manufacturing
Segment Reporting Information [Line Items]
Revenues	657,367	471,789
Earnings (loss) from operations	53,143	36,855
Wheels, Repair & Parts
Segment Reporting Information [Line Items]
Revenues	86,608	108,543
Earnings (loss) from operations	1,114	3,247
Leasing & Services
Segment Reporting Information [Line Items]
Revenues	25,384	24,191
Earnings (loss) from operations	9,777	17,513
Operating Segments
Segment Reporting Information [Line Items]
Earnings (loss) from operations	(22,250)	(21,161)
Operating Segments | Manufacturing
Segment Reporting Information [Line Items]
Revenues	657,464	477,990
Earnings (loss) from operations	53,120	37,288
Assets	1,568,338		1,606,571
Operating Segments | Wheels, Repair & Parts
Segment Reporting Information [Line Items]
Revenues	92,459	124,524
Earnings (loss) from operations	772	3,559
Assets	317,786		306,725
Operating Segments | Leasing & Services
Segment Reporting Information [Line Items]
Revenues	27,133	30,190
Earnings (loss) from operations	11,066	22,965
Assets	776,724		708,799
Operating Segments | Eliminations
Segment Reporting Information [Line Items]
Revenues	(7,697)	(28,181)
Earnings (loss) from operations	(924)	(6,197)
Operating Segments | Unallocated Amount to Segment
Segment Reporting Information [Line Items]
Assets	285,928		$ 368,542
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	(7,697)	(28,181)
Earnings (loss) from operations	(924)	(6,197)
Intersegment Eliminations | Manufacturing
Segment Reporting Information [Line Items]
Revenues	97	6,201
Earnings (loss) from operations	(23)	433
Intersegment Eliminations | Wheels, Repair & Parts
Segment Reporting Information [Line Items]
Revenues	5,851	15,981
Earnings (loss) from operations	(342)	312
Intersegment Eliminations | Leasing & Services
Segment Reporting Information [Line Items]
Revenues	1,749	5,999
Earnings (loss) from operations	1,289	5,452
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Revenues	0	0
Earnings (loss) from operations	$ (22,250)	$ (21,161)