BUSINESS SEGMENTS (External Net Sales from Continuing Operations by Major Product) (Details) - USD ($) $ in Thousands	3 Months Ended															12 Months Ended
	Aug. 31, 2020	[1]	May 31, 2020	[1]	Feb. 29, 2020	[1]	Nov. 30, 2019	[1]	Aug. 31, 2019	May 31, 2019	[1]	Feb. 28, 2019	[1]	Nov. 30, 2018	[1]	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2018
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales	$ 1,409,132		$ 1,341,683		$ 1,340,963		$ 1,384,708		$ 1,543,005	$ 1,605,872		$ 1,402,783		$ 1,277,342		$ 5,476,486	$ 5,829,002	$ 4,643,723
Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																5,476,486	5,829,002	4,643,723
Intersegment
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																0	0	0
North America | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																4,769,933	5,001,116	3,738,493
Europe | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																699,140	817,048	887,038
Europe | Intersegment
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																1,509	1,325	1,119
Corporate | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																7,413	10,838	18,192
Corporate | Intersegment
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																(1,509)	(1,325)	(1,145)
Americas Recycling | Intersegment
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																0	0	26
Unaffiliated Customers | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																5,476,486	5,829,002	4,643,723
Unaffiliated Customers | North America | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																4,769,933	5,001,116	3,738,467
Unaffiliated Customers | Europe | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																697,631	815,723	885,919
Unaffiliated Customers | Corporate | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																8,922	12,163	19,337
Raw material products | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																728,205	966,217	1,181,211
Raw material products | North America | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																718,513	953,858	1,165,998
Raw material products | Europe | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																9,692	12,359	15,213
Raw material products | Corporate | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																0	0	0
Steel products | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																2,285,603	2,409,991	1,809,943
Steel products | North America | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																1,738,556	1,763,017	1,099,286
Steel products | Europe | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																547,047	646,974	710,657
Steel products | Corporate | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																0	0	0
Downstream products | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																2,062,358	2,070,817	1,303,118
Downstream products | North America | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																1,943,126	1,936,994	1,160,373
Downstream products | Europe | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																119,232	133,823	142,745
Downstream products | Corporate | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																0	0	0
Other | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																400,320	381,977	349,451
Other | North America | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																369,738	347,247	312,810
Other | Europe | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																21,660	22,567	17,304
Other | Corporate | Segments
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																$ 8,922	$ 12,163	$ 19,337

[1] Excludes discontinued operations. (2) Fourth quarter results include a $32.1 million charge for a working capital adjustment related to the Acquisition, which was recorded subsequent to the end of the allowable one-year measurement period.