EARNINGS PER SHARE (Calculations of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Aug. 31, 2023	Aug. 31, 2022	Aug. 31, 2021
Earnings Per Share [Abstract]
Net earnings	$ 859,760	$ 1,217,262	$ 412,865
Earnings Per Share, Basic [Abstract]
Average basic shares outstanding (in shares)	117,077,703	120,648,090	120,338,357
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Effect of dilutive securities (in shares)	1,528,568	1,724,296	1,645,140
Diluted earnings per share from continuing operations attributable to CMC (USD per share)	$ 7.25	$ 9.95	$ 3.38
Weighted Average Number of Shares Outstanding, Diluted, Total	118,606,271	122,372,386	121,983,497