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BUSINESS SEGMENTS (External Net Sales from Continuing Operations by Major Product) (Details) - USD ($) $ in Thousands	3 Months Ended															12 Months Ended
	Aug. 31, 2018	[1]	May 31, 2018	[1]	Feb. 28, 2018	[1]	Nov. 30, 2017	[1]	Aug. 31, 2017	May 31, 2017	[1]	Feb. 28, 2017	[1]	Nov. 30, 2016	[1]	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales	$ 1,308,438		$ 1,204,484		$ 1,054,268		$ 1,076,533		$ 1,084,130	$ 1,044,713		$ 862,298		$ 852,928		$ 4,643,723	$ 3,844,069	$ 3,596,068
Steel products
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																3,114,227	2,584,359	2,620,452
Nonferrous scrap
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																630,609	506,220	364,690
Ferrous scrap
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																550,602	413,441	266,326
Construction materials
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																249,538	228,910	234,513
Other
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																$ 98,747	$ 111,139	$ 110,087
[1] Excludes discontinued operations. See Note 3, Changes in Business

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
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-Name Accounting Standards Codification
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