Segment Information - Segments Internal Financial Reports (Detail) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2021	Aug. 31, 2020	Aug. 31, 2019
Segment Reporting Information [Line Items]
Revenue	$ 1,747,981	$ 2,792,189	$ 3,033,591
Earnings (loss) from operations	40,970	168,429	184,116
Assets	3,390,668	3,173,834	2,990,637
Depreciation and amortization	100,717	109,850	83,731
Capital expenditures	139,011	66,879	198,233
Manufacturing
Segment Reporting Information [Line Items]
Revenue	1,329,987	2,349,971	2,431,499
Earnings (loss) from operations	67,124	197,388	217,583
Wheels, Repair & Parts
Segment Reporting Information [Line Items]
Revenue	298,330	324,670	444,502
Earnings (loss) from operations	6,452	9,032	(2,941)
Leasing & Services
Segment Reporting Information [Line Items]
Revenue	119,664	117,548	157,590
Earnings (loss) from operations	50,021	40,927	64,763
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Earnings (loss) from operations	(82,627)	(78,918)	(95,289)
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue	(121,489)	(58,286)	(173,592)
Earnings (loss) from operations	(26,010)	(39,809)	(32,799)
Intersegment Eliminations | Manufacturing
Segment Reporting Information [Line Items]
Revenue	92,424	2,952	97,086
Earnings (loss) from operations	6,899	54	6,370
Intersegment Eliminations | Wheels, Repair & Parts
Segment Reporting Information [Line Items]
Revenue	9,118	12,606	48,266
Earnings (loss) from operations	103	(900)	902
Intersegment Eliminations | Leasing & Services
Segment Reporting Information [Line Items]
Revenue	19,947	42,728	28,240
Earnings (loss) from operations	19,008	40,655	25,527
Operating Segments
Segment Reporting Information [Line Items]
Earnings (loss) from operations	(82,627)	(78,918)	(95,289)
Operating Segments | Manufacturing
Segment Reporting Information [Line Items]
Revenue	1,422,411	2,352,923	2,528,585
Earnings (loss) from operations	74,023	197,442	223,953
Assets	1,493,467	1,301,715	1,606,571
Depreciation and amortization	67,845	78,010	49,240
Capital expenditures	26,627	48,201	85,155
Operating Segments | Wheels, Repair & Parts
Segment Reporting Information [Line Items]
Revenue	307,448	337,276	492,768
Earnings (loss) from operations	6,555	8,132	(2,039)
Assets	260,904	271,862	306,725
Depreciation and amortization	11,961	12,567	13,024
Capital expenditures	8,636	11,662	13,291
Operating Segments | Leasing & Services
Segment Reporting Information [Line Items]
Revenue	139,611	160,276	185,830
Earnings (loss) from operations	69,029	81,582	90,290
Assets	949,380	739,025	708,799
Depreciation and amortization	20,911	19,273	21,467
Capital expenditures	103,748	7,016	99,787
Operating Segments | Unallocated, including cash
Segment Reporting Information [Line Items]
Assets	$ 686,917	$ 861,232	$ 368,542