Restatement of Previously Issued Financial Information - Summary of Impacts of the Restatement Adjustments on Previously Reported Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	May 31, 2019	Feb. 28, 2019	Nov. 30, 2018	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	May 31, 2019	May 31, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	$ 54,713	$ 248,304	$ 347,115	$ 181,620	$ 165,959	$ 187,182	$ 650,132	$ 534,761
Other comprehensive income (loss), net of tax:
Postretirement benefit plan activity	1,496			3,417			5,599	8,153
Unrealized net gain (loss) on available for sale investments	0			6,286			0	13,480
Cash flow hedges	(15,817)			413			(7,155)	1,472
Foreign currency translation adjustment				(10,188)				(10,047)
Other comprehensive income (loss), net of tax	(22,313)	$ 14,884	$ 389	(72)	$ 10,111	$ 3,019	(7,040)	13,058
Comprehensive income	32,400			181,548			643,092	547,819
Less comprehensive income attributable to noncontrolling interests	93			(187)			(758)	(699)
Comprehensive income attributable to CHS Inc.	$ 32,307			181,735			$ 643,850	548,518
As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)				229,146				575,391
Other comprehensive income (loss), net of tax:
Postretirement benefit plan activity				3,417				10,755
Unrealized net gain (loss) on available for sale investments				6,286				13,480
Cash flow hedges				413				1,472
Foreign currency translation adjustment				(11,617)				(11,763)
Other comprehensive income (loss), net of tax				(1,501)				13,944
Comprehensive income				227,645				589,335
Less comprehensive income attributable to noncontrolling interests				(187)				(699)
Comprehensive income attributable to CHS Inc.				227,832				590,034
Restatement Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)				(47,526)				(40,630)
Other comprehensive income (loss), net of tax:
Postretirement benefit plan activity				0				(2,602)
Unrealized net gain (loss) on available for sale investments				0				0
Cash flow hedges				0				0
Foreign currency translation adjustment				1,429				1,716
Other comprehensive income (loss), net of tax				1,429				(886)
Comprehensive income				(46,097)				(41,516)
Less comprehensive income attributable to noncontrolling interests				0				0
Comprehensive income attributable to CHS Inc.				$ (46,097)				$ (41,516)