CONDENSED CONSOLIDATED STATEMENTS OF EARNINGS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015
Income Statement [Abstract]
Net sales	$ 1,019,697	$ 1,391,117	$ 2,174,556	$ 3,071,107
Costs and expenses:
Cost of goods sold	884,876	1,244,042	1,882,118	2,744,109
Selling, general and administrative expenses	93,918	109,602	195,826	222,985
Loss on debt extinguishment	11,365	0	11,365	0
Interest expense	16,625	19,252	34,929	38,309
Total costs and expenses	1,006,784	1,372,896	2,124,238	3,005,403
Earnings from continuing operations before income taxes	12,913	18,221	50,318	65,704
Income taxes	2,064	4,756	13,836	17,974
Earnings from continuing operations	10,849	13,465	36,482	47,730
Loss from discontinued operations before income taxes (benefit)	(446)	(7,268)	(1,018)	(9,370)
Income taxes (benefit)	(99)	0	(101)	(21)
Loss from discontinued operations	(347)	(7,268)	(917)	(9,349)
Net earnings	10,502	6,197	35,565	38,381
Less net earnings attributable to noncontrolling interests	$ 0	0	0	0
Net earnings attributable to CMC		$ 6,197	$ 35,565	$ 38,381
Basic earnings (loss) per share attributable to CMC:
Earnings from continuing operations (in USD per share)	$ 0.09	$ 0.12	$ 0.32	$ 0.41
Loss from discontinued operations (in USD per share)	0.00	(0.06)	(0.01)	(0.08)
Net earnings (in USD per share)	0.09	0.06	0.31	0.33
Diluted earnings (loss) per share attributable to CMC:
Earnings from continuing operations (in USD per share)	0.09	0.11	0.31	0.40
Loss from discontinued operations (in USD per share)	0.00	(0.06)	(0.01)	(0.08)
Net earnings (in USD per share)	0.09	0.05	0.30	0.32
Cash dividends per share (in USD per share)	$ 0.12	$ 0.12	$ 0.24	$ 0.24
Average basic shares outstanding	115,429,550	116,688,162	115,725,896	117,244,406
Average diluted shares outstanding	116,507,591	117,683,476	117,002,822	118,395,844