Investments - Narrative (Details) T in Millions		3 Months Ended				9 Months Ended
	Feb. 01, 2016 USD ($)	May 31, 2016 USD ($) T Tons	Nov. 30, 2015 USD ($)	May 31, 2015 USD ($)	Nov. 30, 2014 USD ($)	May 31, 2016 USD ($) T Tons	May 31, 2015 USD ($)	Feb. 01, 2096 USD ($)	Sep. 30, 2015	Aug. 31, 2015
Schedule of Equity Method Investments [Line Items]
Payments for Repurchase of Redeemable Noncontrolling Interest						$ (153,022,000)	$ (65,981,000)
Equity (income) loss from investments		$ (72,453,000)		$ (34,750,000)		(131,819,000)	(83,548,000)
Short-term investments, net					$ 315,000,000	300,000	170,000,000
Short-term Investments		$ 0				$ 0
CF Nitrogen LLC [Member]
Schedule of Equity Method Investments [Line Items]
Payments to Acquire Equity Method Investments	$ 2,800,000,000
Ownership percentage	11.40%
Supply agreement, term	80 years
Maximum annual granular urea eligible for purchase | T		1.1				1.1
Maximum annual UAN eligible for purchase | Tons		580,000				580,000
Cargill, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership of joint venture partner		50.00%				50.00%
Crack Spread Contingent Payment [Member]
Schedule of Equity Method Investments [Line Items]
Payments to Acquire Business, Contingent Consideration Paid			$ 2,600,000
Energy [Member]
Schedule of Equity Method Investments [Line Items]
Equity (income) loss from investments		$ (1,300,000)		(364,000)		$ (3,487,000)	(1,440,000)
Energy [Member] | National Cooperative Refinery Association [Member]
Schedule of Equity Method Investments [Line Items]
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage									100.00%	88.90%
Payments for Repurchase of Redeemable Noncontrolling Interest						(153,000,000)	(66,000,000)
Accrued liability for contingent crack spread payments related to purchase of noncontrolling interest		24,661,000				24,661,000
Nitrogen Production [Member]
Schedule of Equity Method Investments [Line Items]
Equity (income) loss from investments		(41,257,000)		0		(53,112,000)	0
Nitrogen Production [Member] | CF Nitrogen LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments		2,900,000,000				2,900,000,000
Corporate and Other
Schedule of Equity Method Investments [Line Items]
Equity (income) loss from investments		$ (23,965,000)		(26,422,000)		$ (67,068,000)	(69,681,000)
Corporate and Other | Ardent Mills [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage		12.00%				12.00%
Board seats held by CHS		1				1
Board seats of equity method investment		5				5
Equity Method Investments		$ 196,000,000				$ 196,000,000
Number of parent companies		3				3
Corporate and Other | Ventura Foods, LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage		50.00%				50.00%
Equity Method Investments		$ 363,000,000				$ 363,000,000
Equity value exceeding carrying value		12,900,000				12,900,000
Ag [Member]
Schedule of Equity Method Investments [Line Items]
Equity (income) loss from investments		$ (5,931,000)		$ (7,964,000)		$ (8,152,000)	$ (12,427,000)
Ag [Member] | TEMCO, LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage		50.00%				50.00%
Equity Method Investments		$ 47,500,000				$ 47,500,000
Scenario, Forecast [Member] | Nitrogen Production [Member] | CF Nitrogen LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments								$ 0