Investment in Quest Resource Management Group, LLC - Net Assets and Liabilities Acquired (Detail) (USD $)	Dec. 31, 2013	Jul. 16, 2013
Business Acquisition [Line Items]
Goodwill	$ 58,337,290
Assets and liabilities acquired including goodwill net	104,050,000
Quest Resource Management Group, LLC [Member]
Business Acquisition [Line Items]
Net assets and liabilities	1,214,804
Goodwill	83,885,196
Assets and liabilities acquired including goodwill net		104,050,000
Quest Resource Management Group, LLC [Member] \| Customer relationships [Member]
Business Acquisition [Line Items]
Intangible assets other than goodwill	12,720,000
Quest Resource Management Group, LLC [Member] \| Trademarks [Member]
Business Acquisition [Line Items]
Intangible assets other than goodwill	$ 6,230,000

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Amount of intangible assets, excluding goodwill, acquired at the acquisition date.

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Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Amount recognized for assets, including goodwill, in excess of (less than) the aggregate liabilities assumed.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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