Goodwill - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Feb. 28, 2019	Feb. 28, 2019	Aug. 31, 2018
Goodwill [Line Items]
Goodwill	$ 169,439	$ 169,439	$ 168,065
Goodwill, Impaired, Accumulated Impairment Loss	471,000	471,000	471,000
Auto and Metals Recycling
Goodwill [Line Items]
Goodwill	169,439	169,439	168,065
Business Combination, Consideration Transferred	2,000
Goodwill, Acquired During Period	2,000	1,575
Reporting Unit \| Auto and Metals Recycling
Goodwill [Line Items]
Goodwill	$ 1,000	$ 1,000	$ 1,000

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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