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Commitments and Contingencies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified | 3 Months Ended | 6 Months Ended |  | 3 Months Ended | 6 Months Ended |  |  |  |  |  | 3 Months Ended | 6 Months Ended | 12 Months Ended
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Oct. 31, 2014 | Oct. 31, 2013 | Oct. 31, 2014 | Oct. 31, 2013 | Oct. 31, 2014 New York Attorney General Matter [Member] | Oct. 31, 2014 Greenwood Street Landfill [Member] | Oct. 31, 2014 Greenwood Street Landfill [Member] Administrative Penalty [Member] | Oct. 31, 2014 Minimum [Member] New York Attorney General Matter [Member] | Jul. 31, 2014 General and Administration Costs [Member] New York Attorney General Matter [Member] | Oct. 31, 2014 General and Administration Costs [Member] Greenwood Street Landfill [Member] | Oct. 31, 2014 Potsdam Environmental Remediation Liability [Member] acre | Apr. 30, 2011 Potsdam Environmental Remediation Liability [Member] | May 31, 2009 Potsdam Environmental Remediation Liability [Member] | Sep. 30, 2011 Potsdam Environmental Remediation Liability [Member] Waste-Stream Inc. [Member] | Nov. 30, 2011 Potsdam Environmental Remediation Liability [Member] Motors Liquidation Trust [Member] | Oct. 31, 2014 Southbridge Landfill [Member] Condition One [Member] | Jul. 31, 2014 Southbridge Landfill [Member] Condition One [Member] | Oct. 31, 2014 Southbridge Landfill [Member] Condition One [Member] | Apr. 30, 2014 Southbridge Landfill [Member] Condition One [Member]
Contingencies And Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum acquisition value for post acquisition notice |  |  |  |  |  |  |  | $ 350 |  |  |  |  |  |  |  |  |  |  |
Litigation settlement |  |  |  |  | 100 | 67 | 201 |  |  |  |  |  |  |  |  |  |  |  |
Litigation settlement charge |  |  |  |  |  |  |  |  | 100 | 172 |  |  |  |  |  |  |  |  |
Scrap yard and solid waste transfer station |  |  |  |  |  |  |  |  |  |  | 25 |  |  |  |  |  |  |  |
Estimate of total undiscounted costs associated with implementing the preferred remedies |  |  |  |  |  |  |  |  |  |  |  | 12,130 | 10,219 |  |  |  |  |  |
Future remediation costs |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,000 | 100 |  |  |  |
Risk free interest rate |  |  |  |  |  |  |  |  |  |  | 2.00% |  |  |  |  |  |  |  |
Anticipated remediation costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,997 |
Loss contingency range of possible loss minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 850 |  | 850 |
Loss contingency range of possible loss maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,997 |  | 2,997 |
Environmental remediation charge | $ 375 | $ 150 | $ 450 | $ 150 |  |  |  |  |  |  |  |  |  |  |  | $ 375 | $ 75 |  | $ 400

X
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- Definition The face value of future remediation costs to be paid by GM. + References No definition available. + Details
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- Definition The acquisition notification limit agreed to with the New York Attorney General as a part of our settlement. + References No definition available. + Details
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- Definition Rate applied to the undiscounted amount of environmental loss contingencies to arrive at the present value recorded as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 5.Y.Q1) -URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 5 -Section Y -Paragraph Question 1 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859 + Details
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