Equities Changes in Equity (Details) - USD ($) $ in Thousands		3 Months Ended						9 Months Ended
	Sep. 01, 2018	May 31, 2019	Feb. 28, 2019	Nov. 30, 2018	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	May 31, 2019	May 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 8,165,028	$ 8,402,229	$ 8,292,092	$ 8,165,028	$ 7,866,357	$ 7,742,948	$ 7,705,640	$ 8,165,028	$ 7,705,640
Reversal of prior year patronage and redemption estimates		45,815	81,681	24,072	1,649	1,060	1,561
Patronage Refunds		(689)	(74,980)		0	0
Redemptions of equities		(45,644)	(6,681)	(24,072)	(1,649)	(1,060)	(1,561)
Preferred stock dividends			(42,167)	(84,334)		(42,167)	(84,334)
Other, net		(470)	(1,654)	3,319	(2,236)	(1,942)	2,044
Net income (loss)		54,713	248,304	347,115	181,620	165,959	187,182	650,132	534,761
Net income (loss) attributable to CHS Inc.		54,620			181,807			650,890	535,460
Net income (loss) attributable to noncontrolling interests		93			(187)			(758)	(699)
Other comprehensive income (loss), net of tax		(22,313)	14,884	389	(72)	10,111	3,019	(7,040)	13,058
Estimated 2019 cash patronage refunds		(15,494)	(69,400)	(89,344)	(72,868)	3,823	(50,702)
Estimated 2019 equity redemptions		(6,438)	(39,850)	(50,081)	(51,965)	(12,375)	(19,901)
Ending Balance		8,411,709	8,402,229	8,292,092	7,920,836	7,866,357	7,742,948	8,411,709	7,920,836
Capital equity certificates [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	3,837,580	3,749,227	3,789,158	3,837,580	3,870,219	3,885,139	3,906,426	3,837,580	3,906,426
Reversal of prior year patronage and redemption estimates		45,815	6,681	24,072	1,649	1,060	1,561
Patronage Refunds		0	0		0	0
Redemptions of equities		(34,798)	(5,988)	(22,004)	(1,412)	(953)	(1,449)
Other, net		(1,285)	(774)	(409)	(1,849)	(2,652)	(1,498)
Estimated 2019 equity redemptions		(6,438)	(39,850)	(50,081)	(51,965)	(12,375)	(19,901)
Ending Balance		3,752,521	3,749,227	3,789,158	3,816,642	3,870,219	3,885,139	3,752,521	3,816,642
Nonpatronage Equity Certificates [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	29,498	29,241	29,315	29,498	29,656	29,717	29,836	29,498	29,836
Reversal of prior year patronage and redemption estimates		0	0	0	0	0	0
Patronage Refunds		0	0		0	0
Redemptions of equities		(34)	(74)	(183)	(18)	(16)	(53)
Other, net					(1)	(45)	(66)
Ending Balance		29,207	29,241	29,315	29,637	29,656	29,717	29,207	29,637
Non-qualified Equity Certificates [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	742,378	746,460	740,467	742,378	407,417	404,984	405,387	742,378	405,387
Reversal of prior year patronage and redemption estimates		0	(345,330)	0	0	(126,333)	0
Patronage Refunds		3,212	349,353		(27)	128,858
Redemptions of equities		(10,812)	(619)	(1,885)	(219)	(91)	(59)
Other, net		(3,722)	2,589	(26)	(36)	(1)	(344)
Ending Balance		735,138	746,460	740,467	407,135	407,417	404,984	735,138	407,135
Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	2,264,038	2,264,038	2,264,038	2,264,038	2,264,038	2,264,038	2,264,038	2,264,038	2,264,038
Patronage Refunds		0	0		0	0
Redemptions of equities		0	0	0	0	0	0
Ending Balance		2,264,038	2,264,038	2,264,038	2,264,038	2,264,038	2,264,038	2,264,038	2,264,038
Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(199,915)	(189,348)	(204,232)	(199,915)	(167,230)	(177,341)	(180,360)	(199,915)	(180,360)
Patronage Refunds		0	0		0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				(4,706)
Other comprehensive income (loss), net of tax		(22,313)	14,884	389	(72)	10,111	3,019
Ending Balance		(211,661)	(189,348)	(204,232)	(167,302)	(167,230)	(177,341)	(211,661)	(167,302)
Capital Reserves [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	1,482,003	1,794,279	1,663,971	1,482,003	1,450,326	1,324,372	1,267,808	1,482,003	1,267,808
Reversal of prior year patronage and redemption estimates		0	420,330	0	0	126,333	0
Patronage Refunds		(3,901)	(424,333)		27	(128,858)
Preferred stock dividends			(42,167)	(84,334)		(42,167)	(84,334)
Other, net		4,526	(2,888)	3,436	(252)	816	3,954
Net income (loss) attributable to CHS Inc.		54,620	248,766	347,504	181,807	166,007	187,646
Estimated 2019 cash patronage refunds		(15,494)	(69,400)	(89,344)	(72,868)	3,823	(50,702)
Ending Balance		1,834,030	1,794,279	1,663,971	1,559,040	1,450,326	1,324,372	1,834,030	1,559,040
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	9,446	8,332	9,375	9,446	11,931	12,039	12,505	9,446	12,505
Patronage Refunds		0	0		0	0
Other, net		11	(581)	318	(98)	(60)	(2)
Net income (loss) attributable to noncontrolling interests		93	(462)	(389)	(187)	(48)	(464)
Ending Balance		$ 8,436	$ 8,332	9,375	$ 11,646	$ 11,931	$ 12,039	$ 8,436	$ 11,646
Accounting Standards Update 2016-01
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ (4,700)			0
Accounting Standards Update 2016-01 | Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				4,706
Accounting Standards Update 2016-01 | Capital Reserves [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				(4,706)
Accounting Standards Update 2016-01 | Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				$ 0