Segment Information Segment Operating Income Reconciliation to Consolidated (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2017	May 31, 2016	May 31, 2017	May 31, 2016
Segment Reporting Information [Line Items]
Operating income (loss)	$ 19,147	$ 14,886	$ 33,905	$ (26,217)
Restructuring charges and other exit-related activities	(93)	(542)	200	(7,758)
Interest expense	(2,131)	(2,905)	(5,969)	(6,779)
Other income (expense), net	524	(81)	1,318	763
Income (loss) from continuing operations before income taxes	17,540	11,900	29,254	(32,233)
Operating Segments
Segment Reporting Information [Line Items]
Operating income (loss)	30,212	28,116	64,163	5,354
Operating Segments | Auto and Metals Recycling
Segment Reporting Information [Line Items]
Operating income (loss)	29,801	26,870	68,579	2,555
Operating Segments | Steel Manufacturing Business
Segment Reporting Information [Line Items]
Operating income (loss)	411	1,246	(4,416)	2,799
Segment Reconciling Items
Segment Reporting Information [Line Items]
Restructuring charges and other exit-related activities	(93)	(542)	200	(7,758)
Corporate and eliminations
Segment Reporting Information [Line Items]
Operating income (loss)	$ (10,972)	$ (12,688)	$ (30,458)	$ (23,813)