Segment Reporting - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Nov. 30, 2017	Nov. 30, 2016	Aug. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 8,048,889	$ 8,048,250
Operating earnings (loss)	176,881	186,491
(Gain) loss on investments	(2,819)	7,401
Interest Expense	40,702	38,265
Other (income) loss	(22,195)	(44,401)
Equity (income) loss from investments	(38,362)	(40,328)
Income (loss) before income taxes	199,555	225,554
Total assets	16,784,423		$ 15,973,756
Energy [Member]
Segment Reporting Information [Line Items]
Revenues	2,087,703	1,700,180
Operating earnings (loss)	117,173	72,780
(Gain) loss on investments	0	0
Interest Expense	5,635	4,268
Other (income) loss	(393)	(309)
Equity (income) loss from investments	(1,152)	(1,162)
Income (loss) before income taxes	113,083	69,983
Ag [Member]
Segment Reporting Information [Line Items]
Revenues	6,086,680	6,435,994
Operating earnings (loss)	60,822	109,597
(Gain) loss on investments	(2,819)	7,385
Interest Expense	17,604	16,339
Other (income) loss	(20,228)	(17,923)
Equity (income) loss from investments	(8,254)	(5,417)
Income (loss) before income taxes	74,519	109,213
Nitrogen Production [Member]
Segment Reporting Information [Line Items]
Revenues	0	0
Operating earnings (loss)	(3,135)	(4,029)
(Gain) loss on investments	0	0
Interest Expense	13,272	12,736
Other (income) loss	(1,738)	(29,106)
Equity (income) loss from investments	(20,335)	(14,696)
Income (loss) before income taxes	5,666	27,037
Foods [Member]
Segment Reporting Information [Line Items]
Revenues	0	0
Operating earnings (loss)	(2,467)	(2,797)
(Gain) loss on investments	0	0
Interest Expense	0	0
Other (income) loss	0	0
Equity (income) loss from investments	(3,440)	(13,369)
Income (loss) before income taxes	973	10,572
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	18,775	27,441
Operating earnings (loss)	4,488	10,940
(Gain) loss on investments	0	16
Interest Expense	4,581	7,974
Other (income) loss	(226)	(115)
Equity (income) loss from investments	(5,181)	(5,684)
Income (loss) before income taxes	5,314	8,749
Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	(144,269)	(115,365)
Operating earnings (loss)	0	0
(Gain) loss on investments	0	0
Interest Expense	(390)	(3,052)
Other (income) loss	390	3,052
Equity (income) loss from investments	0	0
Income (loss) before income taxes	0	0
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	0	0
Intersegment Eliminations [Member] | Energy [Member]
Segment Reporting Information [Line Items]
Revenues	(137,204)	(110,087)
Intersegment Eliminations [Member] | Ag [Member]
Segment Reporting Information [Line Items]
Revenues	(4,033)	(3,765)
Intersegment Eliminations [Member] | Nitrogen Production [Member]
Segment Reporting Information [Line Items]
Revenues	0	0
Intersegment Eliminations [Member] | Foods [Member]
Segment Reporting Information [Line Items]
Revenues	0	0
Intersegment Eliminations [Member] | Corporate and Other
Segment Reporting Information [Line Items]
Revenues	(3,032)	(1,513)
Intersegment Eliminations [Member] | Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	$ 144,269	$ 115,365