Segment Reporting - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	Feb. 28, 2018	Feb. 28, 2017	Aug. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 6,851,093	$ 7,320,406	$ 14,899,982	$ 15,368,656
Operating earnings (loss)	(32,884)	10,507	143,997	196,998
(Gain) loss on investments	(4,100)	(2,782)	(6,919)	4,619
Interest Expense	40,176	39,945	80,878	78,210
Other (income) loss	(14,969)	(14,453)	(37,164)	(58,854)
Equity (income) loss from investments	(39,441)	(35,800)	(77,803)	(76,128)
Income (loss) before income taxes	(14,550)	23,597	185,005	249,151
Total assets	17,084,862		17,084,862		$ 15,973,756
Energy [Member]
Segment Reporting Information [Line Items]
Revenues	1,781,047	1,529,034	3,868,750	3,229,214
Operating earnings (loss)	10,372	19,506	127,545	92,286
(Gain) loss on investments	0	0	0	0
Interest Expense	2,629	3,565	8,264	7,833
Other (income) loss	(627)	(187)	(1,020)	(496)
Equity (income) loss from investments	(660)	(486)	(1,812)	(1,648)
Income (loss) before income taxes	9,030	16,614	122,113	86,597
Total assets	4,236,271		4,236,271
Ag [Member]
Segment Reporting Information [Line Items]
Revenues	5,163,803	5,855,331	11,250,483	12,291,325
Operating earnings (loss)	(29,967)	(14,291)	30,855	95,306
(Gain) loss on investments	(1,992)	(690)	(4,811)	6,695
Interest Expense	22,784	16,850	40,388	33,189
Other (income) loss	(14,286)	(17,686)	(34,514)	(35,609)
Equity (income) loss from investments	(5,567)	(3,455)	(13,821)	(8,872)
Income (loss) before income taxes	(30,906)	(9,310)	43,613	99,903
Total assets	7,852,648		7,852,648
Nitrogen Production [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating earnings (loss)	(7,239)	(4,385)	(10,374)	(8,414)
(Gain) loss on investments	0	0	0	0
Interest Expense	12,676	12,182	25,948	24,918
Other (income) loss	(433)	(464)	(2,171)	(29,570)
Equity (income) loss from investments	(24,012)	(21,557)	(44,347)	(36,253)
Income (loss) before income taxes	4,530	5,454	10,196	32,491
Total assets	2,773,870		2,773,870
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	13,168	31,430	31,943	58,871
Operating earnings (loss)	(6,050)	9,677	(4,029)	17,820
(Gain) loss on investments	(2,108)	(2,092)	(2,108)	(2,076)
Interest Expense	2,665	11,411	7,245	19,385
Other (income) loss	(201)	(179)	(426)	(294)
Equity (income) loss from investments	(9,202)	(10,302)	(17,823)	(29,355)
Income (loss) before income taxes	2,796	10,839	9,083	30,160
Total assets	2,222,073		2,222,073
Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	(106,925)	(95,389)	(251,194)	(210,754)
Operating earnings (loss)	0	0	0	0
(Gain) loss on investments	0	0	0	0
Interest Expense	(578)	(4,063)	(967)	(7,115)
Other (income) loss	578	4,063	967	7,115
Equity (income) loss from investments	0	0	0	0
Income (loss) before income taxes	0	0	0	0
Total assets	0		0
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Intersegment Eliminations [Member] | Energy [Member]
Segment Reporting Information [Line Items]
Revenues	(101,609)	(89,094)	(238,813)	(199,181)
Intersegment Eliminations [Member] | Ag [Member]
Segment Reporting Information [Line Items]
Revenues	(3,574)	(4,758)	(7,607)	(8,523)
Intersegment Eliminations [Member] | Nitrogen Production [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Intersegment Eliminations [Member] | Corporate and Other
Segment Reporting Information [Line Items]
Revenues	(1,742)	(1,537)	(4,774)	(3,050)
Intersegment Eliminations [Member] | Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	$ 106,925	$ 95,389	$ 251,194	$ 210,754