Investments - Schedule of Equity Method Investment Balance Sheet and Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Aug. 31, 2018	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Feb. 28, 2018	Feb. 28, 2017	May 31, 2018	May 31, 2017	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
Schedule of Equity Method Investments [Line Items]
Earnings attributable to CHS Inc.	$ 240,447	$ 181,807	$ 166,007	$ 187,646	$ (74,450)	$ (71,533)	$ 14,211	$ 203,364	$ 353,653	$ 217,575	$ 535,460	$ 146,042	$ 775,907	$ 71,592	$ 383,249
CF Industries Nitrogen
Schedule of Equity Method Investments [Line Items]
Current assets	576,076				394,089								576,076	394,089
Non-current assets	7,447,594				7,314,629								7,447,594	7,314,629
Current liabilities	215,104				390,206								215,104	390,206
Non-current liabilities	71				6								71	6
Net sales													2,449,695	2,051,159	1,027,142
Gross profit													423,612	195,142	243,911
Net earnings													401,295	123,965	186,665
Earnings attributable to CHS Inc.													106,895	66,530	74,700
Ventura Foods and Ardent Mills
Schedule of Equity Method Investments [Line Items]
Current assets	1,462,590				1,483,384								1,462,590	1,483,384
Non-current assets	2,331,295				2,358,434								2,331,295	2,358,434
Current liabilities	671,928				685,462								671,928	685,462
Non-current liabilities	$ 693,360				$ 765,078								693,360	765,078
Net sales													5,882,035	5,762,849	5,694,622
Gross profit													601,927	673,329	677,920
Net earnings													226,776	265,126	265,025
Earnings attributable to CHS Inc.													$ 46,069	$ 60,716	$ 88,936