Segment Information - Segment Revenue Reconciliation to Consolidated (Details) - USD ($) $ in Thousands	3 Months Ended
	Nov. 30, 2018	Nov. 30, 2017
Segment Reporting Information [Line Items]
Revenues	$ 564,020	$ 483,279
Auto and Metals Recycling
Segment Reporting Information [Line Items]
Revenues	433,634	393,295
Operating Segments | Auto and Metals Recycling
Segment Reporting Information [Line Items]
Revenues	436,412	398,054
Operating Segments | Cascade Steel and Scrap
Segment Reporting Information [Line Items]
Revenues	130,386	89,984
Less: Intersegment revenues | Auto and Metals Recycling
Segment Reporting Information [Line Items]
Revenues	$ (2,778)	$ (4,759)