Segment Reporting - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2018	May 31, 2017	Aug. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 9,027,525	$ 8,614,090	$ 23,927,508	$ 23,982,746
Operating earnings (loss)	140,844	(230,297)	284,842	(33,299)
(Gain) loss on disposal of business	(124,050)	0	(131,755)	0
Interest Expense	49,340	39,201	130,218	117,411
Other (income) loss	(14,622)	(11,947)	(51,000)	(66,183)
Equity (income) loss from investments	(59,308)	(48,393)	(137,111)	(124,521)
Income (loss) before income taxes	289,484	(209,158)	474,490	39,994
Total assets	16,935,779		16,935,779		$ 15,973,756
Energy [Member]
Segment Reporting Information [Line Items]
Revenues	2,009,907	1,638,107	5,878,657	4,867,321
Operating earnings (loss)	31,525	(5,723)	159,070	86,563
(Gain) loss on disposal of business	(65,903)		(65,903)
Interest Expense	3,496	4,343	11,760	12,176
Other (income) loss	(472)	(332)	(1,492)	(828)
Equity (income) loss from investments	(967)	(391)	(2,779)	(2,039)
Income (loss) before income taxes	95,371	(9,343)	217,484	77,254
Total assets	4,208,214		4,208,214
Ag [Member]
Segment Reporting Information [Line Items]
Revenues	7,125,024	7,053,991	18,375,507	19,345,316
Operating earnings (loss)	115,052	(226,668)	145,907	(131,363)
(Gain) loss on disposal of business	5		(7,700)
Interest Expense	28,854	16,609	69,242	49,798
Other (income) loss	(13,891)	(12,886)	(45,511)	(41,801)
Equity (income) loss from investments	(11,359)	(9,199)	(25,180)	(18,071)
Income (loss) before income taxes	111,443	(221,192)	155,056	(121,289)
Total assets	7,510,962		7,510,962
Nitrogen Production [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating earnings (loss)	(4,153)	(5,619)	(14,527)	(14,033)
(Gain) loss on disposal of business	0		0
Interest Expense	13,119	10,708	39,067	35,626
Other (income) loss	(441)	(477)	(2,612)	(30,047)
Equity (income) loss from investments	(35,639)	(24,534)	(79,986)	(60,787)
Income (loss) before income taxes	18,808	8,684	29,004	41,175
Total assets	2,810,256		2,810,256
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	14,074	26,820	46,018	85,691
Operating earnings (loss)	(1,580)	7,713	(5,608)	25,534
(Gain) loss on disposal of business	(58,152)		(58,152)
Interest Expense	4,324	8,127	11,569	27,512
Other (income) loss	(271)	1,162	(2,805)	(1,208)
Equity (income) loss from investments	(11,343)	(14,269)	(29,166)	(43,624)
Income (loss) before income taxes	63,862	12,693	72,946	42,854
Total assets	2,406,347		2,406,347
Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	(121,480)	(104,828)	(372,674)	(315,582)
Operating earnings (loss)	0	0	0	0
(Gain) loss on disposal of business	0		0
Interest Expense	(453)	(586)	(1,420)	(7,701)
Other (income) loss	453	586	1,420	7,701
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	(116,286)	(97,876)	(355,099)	(297,057)
Intersegment Eliminations [Member] | Ag [Member]
Segment Reporting Information [Line Items]
Revenues	(3,784)	(7,545)	(11,391)	(16,068)
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	(1,410)	593	(6,184)	(2,457)
Intersegment Eliminations [Member] | Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	$ 121,480	$ 104,828	$ 372,674	$ 315,582