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
	Nov. 30, 2018	Nov. 30, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	$ 347,115	$ 187,182
Other comprehensive income (loss), net of tax:
Postretirement benefit plan activity	2,101	1,594
Unrealized net gain (loss) on available for sale investments	0	3,640
Cash flow hedges	(1,307)	(4)
Foreign currency translation adjustment		(2,211)
Other comprehensive income (loss), net of tax	389	3,019
Comprehensive income	347,504	190,201
Less comprehensive income attributable to noncontrolling interests	(389)	(464)
Comprehensive income attributable to CHS Inc.	$ 347,893	190,665
As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)		179,619
Other comprehensive income (loss), net of tax:
Postretirement benefit plan activity		4,196
Unrealized net gain (loss) on available for sale investments		3,640
Cash flow hedges		(4)
Foreign currency translation adjustment		(2,607)
Other comprehensive income (loss), net of tax		5,225
Comprehensive income		184,844
Less comprehensive income attributable to noncontrolling interests		(464)
Comprehensive income attributable to CHS Inc.		185,308
Restatement Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)		7,563
Other comprehensive income (loss), net of tax:
Postretirement benefit plan activity		(2,602)
Unrealized net gain (loss) on available for sale investments		0
Cash flow hedges		0
Foreign currency translation adjustment		396
Other comprehensive income (loss), net of tax		(2,206)
Comprehensive income		5,357
Less comprehensive income attributable to noncontrolling interests		0
Comprehensive income attributable to CHS Inc.		$ 5,357