STOCKHOLDERS’ EQUITY AND EARNINGS PER SHARE ATTRIBUTABLE TO CMC (Narrative) (Details) - USD ($)	3 Months Ended	9 Months Ended
	May. 31, 2015	May. 31, 2015	Oct. 27, 2014
Earnings Per Share [Abstract]
Stock repurchase program, authorized amount			$ 100,000,000.0
Stock repurchase program, shares purchased (shares)	139,383	2,902,218
Stock repurchase program, average purchase price per share (in USD per share)	$ 15.97	$ 14.40
Stock repurchase program, remaining authorized repurchase amount	$ 58,200,000	$ 58,200,000