Segment Reporting - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2017	May 31, 2016	May 31, 2017	May 31, 2016	Aug. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 8,614,090	$ 7,796,588	$ 23,982,746	$ 22,164,710
Operating earnings (loss)	(230,297)	148,060	(33,299)	316,071
(Gain) loss on investments	(393)	(700)	4,226	(9,422)
Interest expense	39,201	37,466	117,411	71,553
Other income	(11,554)	(10,774)	(70,409)	(22,155)
Equity (income) loss from investments	(48,393)	(72,453)	(124,521)	(131,819)
Income (loss) before income taxes	(209,158)	194,521	39,994	407,914
Total assets	17,221,797		17,221,797		$ 17,312,135
Energy [Member]
Segment Reporting Information [Line Items]
Revenues	1,638,107	1,322,624	4,867,321	4,162,685
Operating earnings (loss)	(5,723)	103,614	86,563	214,827
(Gain) loss on investments	0	0	0	0
Interest expense	4,343	(4,270)	12,176	(20,723)
Other income	(332)	(217)	(828)	(174)
Equity (income) loss from investments	(391)	(1,300)	(2,039)	(3,487)
Income (loss) before income taxes	(9,343)	109,401	77,254	239,211
Total assets	4,292,789		4,292,789
Ag [Member]
Segment Reporting Information [Line Items]
Revenues	7,053,991	6,526,714	19,345,316	18,221,420
Operating earnings (loss)	(226,668)	24,432	(131,363)	77,605
(Gain) loss on investments	(393)	(881)	6,302	(6,595)
Interest expense	16,609	24,518	49,798	57,785
Other income	(12,493)	(17,473)	(48,103)	(27,778)
Equity (income) loss from investments	(9,199)	(5,931)	(18,071)	(8,152)
Income (loss) before income taxes	(221,192)	24,199	(121,289)	62,345
Total assets	7,028,635		7,028,635
Nitrogen Production [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating earnings (loss)	(5,619)	253	(14,033)	(5,506)
(Gain) loss on investments	0	0	0	0
Interest expense	10,708	16,549	35,626	21,286
Other income	(477)	0	(30,047)	0
Equity (income) loss from investments	(24,534)	(41,257)	(60,787)	(53,112)
Income (loss) before income taxes	8,684	24,961	41,175	26,320
Total assets	2,834,040		2,834,040
Foods [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating earnings (loss)	(3,101)	(2,243)	(8,370)	(6,319)
(Gain) loss on investments	0	0	0	0
Interest expense	(231)	645	(231)	2,246
Other income	0	0	0	0
Equity (income) loss from investments	(9,920)	(19,922)	(28,850)	(55,449)
Income (loss) before income taxes	7,050	17,034	20,711	46,884
Total assets	374,007		374,007
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	26,820	25,114	85,691	68,210
Operating earnings (loss)	10,814	22,004	33,904	35,464
(Gain) loss on investments	0	181	(2,076)	(2,827)
Interest expense	8,358	7,951	27,743	18,886
Other income	1,162	(1,011)	868	(2,130)
Equity (income) loss from investments	(4,349)	(4,043)	(14,774)	(11,619)
Income (loss) before income taxes	5,643	18,926	22,143	33,154
Total assets	2,692,326		2,692,326
Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	(104,828)	(77,864)	(315,582)	(287,605)
Operating earnings (loss)	0	0	0	0
(Gain) loss on investments	0	0	0	0
Interest expense	(586)	(7,927)	(7,701)	(7,927)
Other income	586	7,927	7,701	7,927
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	(97,876)	(76,114)	(297,057)	(250,425)
Intersegment Eliminations [Member] | Ag [Member]
Segment Reporting Information [Line Items]
Revenues	(7,545)	(3,016)	(16,068)	(36,032)
Intersegment Eliminations [Member] | Nitrogen Production [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Intersegment Eliminations [Member] | Foods [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Intersegment Eliminations [Member] | Corporate and Other
Segment Reporting Information [Line Items]
Revenues	593	1,266	(2,457)	(1,148)
Intersegment Eliminations [Member] | Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	$ 104,828	$ 77,864	$ 315,582	$ 287,605