Commitments and Contingencies - Recycling Operations and Other Legacy (Details)	1 Months Ended		12 Months Ended
	Dec. 31, 2017 potentially_responsible_party	Jan. 31, 2017 USD ($)	Aug. 31, 2019 USD ($) Subarea	Aug. 31, 2018 USD ($)	Aug. 31, 2007 USD ($)	Aug. 31, 2017 USD ($)	Jan. 30, 2017 potentially_responsible_party party	Aug. 31, 2016 USD ($)
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies			$ 51,799,000	$ 53,832,000		$ 48,398,000
Parties named in Litigation | party							30
Liabilities Established			1,302,000	9,172,000
Insurance Receivable			89,000,000	36,000,000
Other Auto and Metals Recycling Business Sites
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies			52,000,000	54,000,000
Portland Harbor Superfund Site
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies			$ 1,000,000	2,000,000
Number Of Potentially Responsible Parties Joining Allocation Process | potentially_responsible_party							100
Number Of Other Potentially Responsible Parties Signing Settlement Agreement and Order on Consent | potentially_responsible_party	3
Number of Years for Pre-Remedial Design	2 years
Liabilities Established				2,000,000
Insurance Receivable				2,000,000
Portland Harbor Superfund Site | Minimum
Loss Contingencies [Line Items]
Site contingency proposed subareas for remedial design | Subarea			8
Site contingency expected completion term for remedial design			3 years
Portland Harbor Superfund Site | Maximum
Loss Contingencies [Line Items]
Site contingency proposed subareas for remedial design | Subarea			10
Site contingency expected completion term for remedial design			4 years
Portland Harbor Superfund Site | Lower Willamette Group
Loss Contingencies [Line Items]
Remedial Investigation and Feasibility Study Costs					$ 155,000,000
Number of Years for Remedial Investigation and Feasibility Study					18 years
Portland Harbor Superfund Site | Potential Responsible Parties
Loss Contingencies [Line Items]
Estimated Cost of Selected Remedy Undiscounted		$ 1,700,000,000
Estimated Cost of Selected Remedy Discounted		$ 1,050,000,000.00
Estimated Cost of Selected Remedy, Discount Rate		7.00%
Site Contingency, Estimated Construction Time Frame		13 years
Portland Harbor Superfund Site | Potential Responsible Parties | Minimum
Loss Contingencies [Line Items]
Site Contingency, Least Costly Remediation Plan Discounted								$ 170,000,000
Estimated Cost of Selected Remedy, Range		(30.00%)
Portland Harbor Superfund Site | Potential Responsible Parties | Maximum
Loss Contingencies [Line Items]
Site Contingency, Most Costly Remediation Plan Discounted								$ 2,500,000,000
Estimated Cost of Selected Remedy, Range		50.00%
Legacy Environmental Site 1 - Remediation of Shredder Residue
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies			$ 4,000,000	4,000,000
Environmental remediation expense accrued in the period				4,000,000
Legacy Environmental Site 1 - Remediation of Shredder Residue | Minimum
Loss Contingencies [Line Items]
Loss contingency, range of possible loss			0
Legacy Environmental Site 1 - Remediation of Shredder Residue | Maximum
Loss Contingencies [Line Items]
Loss contingency, range of possible loss			28,000,000
Legacy Environmental Site 2 - Remediation of Soil and Groundwater Conditions
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies			$ 6,000,000	$ 6,000,000