BUSINESS SEGMENTS (Summary of Certain Financial Information from Continuing Operations by Reportable Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Nov. 30, 2019	Nov. 30, 2018	Aug. 31, 2019
Segment Reporting Information [Line Items]
Net sales	$ 1,384,708	$ 1,277,342
Adjusted EBITDA from continuing operations	159,805	65,536
Total assets	3,808,351		$ 3,758,771
Continuing Operations
Segment Reporting Information [Line Items]
Net sales	1,384,708	1,277,342
Americas Recycling
Segment Reporting Information [Line Items]
Net sales	172,151	240,181
Americas Mills
Segment Reporting Information [Line Items]
Net sales	474,192	373,671
Americas Fabrication
Segment Reporting Information [Line Items]
Net sales	570,377	434,558
International Mill
Segment Reporting Information [Line Items]
Net sales	165,040	226,673
Corporate
Segment Reporting Information [Line Items]
Net sales	2,948	2,259
Intersegment | Continuing Operations
Segment Reporting Information [Line Items]
Net sales	0	0
Intersegment | Americas Recycling
Segment Reporting Information [Line Items]
Net sales	50,110	61,828
Intersegment | Americas Mills
Segment Reporting Information [Line Items]
Net sales	294,701	228,182
Intersegment | Americas Fabrication
Segment Reporting Information [Line Items]
Net sales	1,470	2,553
Intersegment | International Mill
Segment Reporting Information [Line Items]
Net sales	349	351
Intersegment | Corporate
Segment Reporting Information [Line Items]
Net sales	(346,630)	(292,914)
Segments | Continuing Operations
Segment Reporting Information [Line Items]
Net sales	1,384,708	1,277,342
Adjusted EBITDA from continuing operations	159,805	65,536
Total assets	3,808,351		3,758,771
Segments | Americas Recycling
Segment Reporting Information [Line Items]
Net sales	222,261	302,009
Adjusted EBITDA from continuing operations	3,417	15,434
Total assets	251,115		257,517
Segments | Americas Mills
Segment Reporting Information [Line Items]
Net sales	768,893	601,853
Adjusted EBITDA from continuing operations	155,025	113,873
Total assets	1,632,290		1,667,366
Segments | Americas Fabrication
Segment Reporting Information [Line Items]
Net sales	571,847	437,111
Adjusted EBITDA from continuing operations	17,481	(36,996)
Total assets	1,123,785		1,106,420
Segments | International Mill
Segment Reporting Information [Line Items]
Net sales	165,389	227,024
Adjusted EBITDA from continuing operations	11,359	32,779
Total assets	483,718		464,177
Segments | Corporate
Segment Reporting Information [Line Items]
Net sales	(343,682)	(290,655)
Adjusted EBITDA from continuing operations	(27,477)	$ (59,554)
Total assets	$ 317,443		$ 263,291