Equities Changes in Equity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2017	May 31, 2016	May 31, 2017	May 31, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			$ 7,866,250
Reversal of prior year patronage and redemption estimates			157,076
Patronage Refunds			(103,879)
Redemptions of equities			(45,489)
Equity Issued During Period, Value, New Issues			23,162
Preferred stock dividends			(139,760)
Other, net			1,274
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ (46,140)	$ 189,683	177,775	$ 425,675
Net income (loss) attributable to CHS Inc.	(45,185)	190,275	178,532	425,767
Net income (loss) attributable to noncontrolling interests	(955)	(592)	(757)	(92)
Other comprehensive income (loss), net of tax	1,742	$ 14,914	2,026	$ 413
Estimated 2017 cash patronage refunds			(68,229)
Estimated 2017 equity redemptions			(11,250)
Ending Balance	7,858,956		7,858,956
Capital equity certificates [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			3,932,513
Reversal of prior year patronage and redemption estimates			(121,892)
Patronage Refunds			153,589
Redemptions of equities			(43,949)
Equity Issued During Period, Value, New Issues			3,176
Other, net			(7,560)
Estimated 2017 equity redemptions			(11,250)
Ending Balance	3,904,627		3,904,627
Nonpatronage Equity Certificates [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			22,894
Reversal of prior year patronage and redemption estimates			0
Patronage Refunds			0
Redemptions of equities			(154)
Other, net			7,300
Ending Balance	30,040		30,040
Non-qualified Equity Certificates [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			281,767
Reversal of prior year patronage and redemption estimates			0
Patronage Refunds			0
Redemptions of equities			(1,386)
Other, net			(391)
Ending Balance	279,990		279,990
Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			2,244,132
Redemptions of equities			0
Equity Issued During Period, Value, New Issues			19,986
Other, net			(55)
Ending Balance	2,264,063		2,264,063
Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			(211,726)
Other comprehensive income (loss), net of tax			2,026
Ending Balance	(209,700)		(209,700)
Capital Reserves [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			1,582,380
Reversal of prior year patronage and redemption estimates			278,968
Patronage Refunds			(257,468)
Preferred stock dividends			(139,760)
Other, net			3,046
Net income (loss) attributable to CHS Inc.			178,532
Estimated 2017 cash patronage refunds			(68,229)
Ending Balance	1,577,469		1,577,469
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			14,290
Other, net			(1,066)
Net income (loss) attributable to noncontrolling interests			(757)
Ending Balance	$ 12,467		$ 12,467