Revenue - Summary of Revenues Disaggregated by Major Product and Sales Destination (Details) - USD ($) $ in Thousands	3 Months Ended
	Nov. 30, 2020	Nov. 30, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 492,107	$ 405,584
Ferrous Revenues
Disaggregation of Revenue [Line Items]
Revenues	252,206	199,898
Nonferrous Revenues
Disaggregation of Revenue [Line Items]
Revenues	119,709	97,841
Steel Revenues
Disaggregation of Revenue [Line Items]
Revenues	88,414	77,325
Retail and Other Revenues
Disaggregation of Revenue [Line Items]
Revenues	31,778	30,520
Foreign
Disaggregation of Revenue [Line Items]
Revenues	268,399	218,482
Domestic
Disaggregation of Revenue [Line Items]
Revenues	$ 223,708	$ 187,102