EARNINGS PER SHARE (Calculations of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Aug. 31, 2022	Aug. 31, 2021	Aug. 31, 2020
Earnings Per Share [Abstract]
Net earnings from continuing operations	$ 1,217,262	$ 412,865	$ 278,302
Earnings Per Share, Basic [Abstract]
Average basic shares outstanding (in shares)	120,648,090	120,338,357	118,921,854
Basic earnings per share from continuing operations attributable to CMC (USD per share)	$ 10.09	$ 3.43	$ 2.34
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Effect of dilutive securities (in shares)	1,724,296	1,645,140	1,387,767
Diluted earnings per share from continuing operations attributable to CMC (USD per share)	$ 9.95	$ 3.38	$ 2.31
Weighted Average Number of Shares Outstanding, Diluted, Total	122,372,386	121,983,497	120,309,621