BUSINESS SEGMENTS (Summary of Certain Financial Information from Continuing Operations by Reportable Segment and Major Product) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		9 Months Ended
	Feb. 28, 2023	Feb. 28, 2022	Feb. 28, 2023	Feb. 28, 2022	May 31, 2022	Aug. 31, 2022
Segment Reporting Information [Line Items]
Net sales	$ 2,018,003	$ 2,008,888	$ 4,245,316	$ 3,990,689
Adjusted EBITDA	296,687	564,119	699,423	878,141
Total assets	6,484,851		6,484,851			$ 6,237,027
Segments | Continuing Operations
Segment Reporting Information [Line Items]
Net sales	2,018,003	2,008,888	4,245,316	3,990,689
Adjusted EBITDA	296,687	564,119	699,423		$ 878,141
Total assets	6,484,851		6,484,851			6,237,027
Segments | North America
Segment Reporting Information [Line Items]
Net sales	1,640,933	1,614,224	3,457,832	3,267,846
Adjusted EBITDA	299,311	535,463	677,267		803,987
Total assets	4,660,107		4,660,107			4,467,314
Segments | Europe
Segment Reporting Information [Line Items]
Net sales	355,633	395,758	762,146	724,814
Adjusted EBITDA	12,949	81,149	77,454		160,981
Total assets	1,253,468		1,253,468			1,056,101
Segments | Unaffiliated Customers
Segment Reporting Information [Line Items]
Net sales	2,018,003	2,008,888	4,245,316	3,990,689
Segments | Unaffiliated Customers | North America
Segment Reporting Information [Line Items]
Net sales	1,639,993	1,614,224	3,455,241	3,267,846
Segments | Unaffiliated Customers | Europe
Segment Reporting Information [Line Items]
Net sales	354,939	395,349	760,888	723,911
Segments | Raw materials
Segment Reporting Information [Line Items]
Net sales	320,605	372,805	617,792	732,857
Segments | Raw materials | North America
Segment Reporting Information [Line Items]
Net sales	315,711	366,941	608,031	720,033
Segments | Raw materials | Europe
Segment Reporting Information [Line Items]
Net sales	4,894	5,864	9,761	12,824
Segments | Steel Products
Segment Reporting Information [Line Items]
Net sales	903,331	986,461	1,920,729	1,904,648
Segments | Steel Products | North America
Segment Reporting Information [Line Items]
Net sales	630,724	666,047	1,336,186	1,341,089
Segments | Steel Products | Europe
Segment Reporting Information [Line Items]
Net sales	272,607	320,414	584,543	563,559
Segments | Downstream products
Segment Reporting Information [Line Items]
Net sales	589,301	519,294	1,290,817	1,103,762
Segments | Downstream products | North America
Segment Reporting Information [Line Items]
Net sales	539,173	459,753	1,181,107	974,149
Segments | Downstream products | Europe
Segment Reporting Information [Line Items]
Net sales	50,128	59,541	109,710	129,613
Segments | Construction-related solutions
Segment Reporting Information [Line Items]
Net sales	139,844	83,638	301,662	166,137
Segments | Construction-related solutions | North America
Segment Reporting Information [Line Items]
Net sales	122,464	83,638	264,836	166,137
Segments | Construction-related solutions | Europe
Segment Reporting Information [Line Items]
Net sales	17,380	0	36,826	0
Segments | Other
Segment Reporting Information [Line Items]
Net sales	64,922	46,690	114,316	83,285
Segments | Other | North America
Segment Reporting Information [Line Items]
Net sales	31,921	37,845	65,081	66,438
Segments | Other | Europe
Segment Reporting Information [Line Items]
Net sales	9,930	9,530	20,048	17,915
Segments | New Markets Tax Credit Transactions | North America
Segment Reporting Information [Line Items]
Net sales			17,700
Segments | Corporate
Segment Reporting Information [Line Items]
Net sales	21,437	(1,094)	25,338
Adjusted EBITDA	(15,573)	(52,493)
Segments | Corporate | Unaffiliated Customers
Segment Reporting Information [Line Items]
Net sales	23,071	(685)	29,187	(1,068)
Segments | Corporate | Raw materials
Segment Reporting Information [Line Items]
Net sales	0	0	0	0
Segments | Corporate | Steel Products
Segment Reporting Information [Line Items]
Net sales	0	0	0	0
Segments | Corporate | Downstream products
Segment Reporting Information [Line Items]
Net sales	0	0	0	0
Segments | Corporate | Construction-related solutions
Segment Reporting Information [Line Items]
Net sales	0	0	0	0
Segments | Corporate | Other
Segment Reporting Information [Line Items]
Net sales	23,071	(685)	29,187	(1,068)
Segments | Corporate and Other
Segment Reporting Information [Line Items]
Net sales				(1,971)
Adjusted EBITDA			(55,298)		$ (86,827)
Total assets	571,276		571,276			$ 713,612
Intersegment
Segment Reporting Information [Line Items]
Net sales	0	0	0	0
Intersegment | North America
Segment Reporting Information [Line Items]
Net sales	940	0	2,591	0
Intersegment | Europe
Segment Reporting Information [Line Items]
Net sales	694	409	1,258	903
Intersegment | Corporate
Segment Reporting Information [Line Items]
Net sales	$ (1,634)	$ (409)	$ (3,849)	$ (903)