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Energy and Related Sales, Net - Summary of Energy and Related Sales Net (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Energy And Related Sales Net [Abstract] |  |  |
Energy sales | $ 3,258 | $ 3,613 | $ 5,315
Costs to produce | (3,986) | (3,972) | (4,428)
Net | (728) | (359) | 887
Renewable energy credits | 5,854 | 6,500 | 4,777
Total | $ 5,126 | $ 6,141 | $ 5,664

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- Definition Revenue from sales of excess internally generated power, net of costs to produce, and revenue from sales of renewable energy credits. + References No definition available. + Details
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- Definition Energy and Related Sales, Net [Abstract] + References No definition available. + Details
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- Definition Renewable energy credits sales revenue. + References No definition available. + Details
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- Definition Cost incurred in providing energy services during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(d)) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
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- Definition Revenue derived from energy-related services such as supplying various forms of energy from the operation of on-site facilities or cogeneration plants and procurement services provided to energy purchasers. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
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