Revenues - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 6,598,226	$ 6,483,539	$ 14,219,711	$ 14,967,828
Energy
Disaggregation of Revenue [Line Items]
Revenues	1,461,050	1,474,777	3,356,473	3,636,065
Ag
Disaggregation of Revenue [Line Items]
Revenues	5,124,202	4,994,545	10,836,057	11,299,942
Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	12,974	14,217	27,181	31,821
ASC 606
Disaggregation of Revenue [Line Items]
Revenues	2,448,031	2,299,273	5,506,045	5,522,859
ASC 606 | Energy
Disaggregation of Revenue [Line Items]
Revenues	1,375,905	1,310,529	3,069,753	3,173,056
ASC 606 | Ag
Disaggregation of Revenue [Line Items]
Revenues	1,066,783	984,000	2,425,409	2,339,825
ASC 606 | Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	5,343	4,744	10,883	9,978
ASC 815
Disaggregation of Revenue [Line Items]
Revenues	4,120,592	4,141,013	8,638,254	9,353,202
ASC 815 | Energy
Disaggregation of Revenue [Line Items]
Revenues	85,145	164,248	286,720	463,009
ASC 815 | Ag
Disaggregation of Revenue [Line Items]
Revenues	4,035,447	3,976,765	8,351,534	8,890,193
ASC 815 | Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Other Guidance
Disaggregation of Revenue [Line Items]
Revenues	29,603	43,253	75,412	91,767
Other Guidance | Energy
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Other Guidance | Ag
Disaggregation of Revenue [Line Items]
Revenues	21,972	33,780	59,114	69,924
Other Guidance | Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	$ 7,631	$ 9,473	$ 16,298	$ 21,843