Revenues - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2020	May 31, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 7,241,031	$ 8,497,941	$ 21,460,742	$ 23,465,769
Energy
Disaggregation of Revenue [Line Items]
Revenues	890,919	1,738,045	4,247,392	5,374,110
Ag
Disaggregation of Revenue [Line Items]
Revenues	6,337,901	6,745,115	17,173,958	18,045,057
Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	12,211	14,781	39,392	46,602
ASC 606
Disaggregation of Revenue [Line Items]
Revenues	2,794,668	3,783,752	8,294,813	9,415,783
ASC 606 | Energy
Disaggregation of Revenue [Line Items]
Revenues	762,053	1,544,533	3,831,806	4,826,762
ASC 606 | Ag
Disaggregation of Revenue [Line Items]
Revenues	2,026,588	2,234,378	4,446,097	4,574,203
ASC 606 | Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	6,027	4,841	16,910	14,818
ASC 815
Disaggregation of Revenue [Line Items]
Revenues	4,419,493	4,678,601	13,096,694	13,922,624
ASC 815 | Energy
Disaggregation of Revenue [Line Items]
Revenues	128,866	193,512	415,586	547,348
ASC 815 | Ag
Disaggregation of Revenue [Line Items]
Revenues	4,290,627	4,485,089	12,681,108	13,375,276
ASC 815 | Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Other Guidance
Disaggregation of Revenue [Line Items]
Revenues	26,870	35,588	69,235	127,362
Other Guidance | Energy
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Other Guidance | Ag
Disaggregation of Revenue [Line Items]
Revenues	20,686	25,648	46,753	95,578
Other Guidance | Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	$ 6,184	$ 9,940	$ 22,482	$ 31,784