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Related Party Transactions (Narrative) (Details) - USD ($) |  | 12 Months Ended | 48 Months Ended | 105 Months Ended
--- | --- | --- | --- | ---
Dec. 18, 2007 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2017 | Dec. 31, 2017
Related Party Transaction [Line Items] |  |  |  |  |  |
Cost incurred, development costs |  |  |  | $ 252,000 |  |
Working interest percent | 15.00% |  |  |  |  |
Related party allowance for doubtful accounts receivable |  | $ 14,000 | $ 14,000 |  | $ 14,000 | $ 14,000
Accounts receivable-related party, allowance for doubtful accounts |  | 159,000 | 159,000 |  | 159,000 | 159,000
Accounts receivable - related parties balance |  |  |  |  |  |
Methane gas sales |  | $ 4,683,000 | 4,113,000 | $ 5,631,000 |  |
Methane Project [Member] |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Percent of net profits, interest |  | 7.50% |  |  |  |
Hoactzin Partners, L.P. [Member] |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Related parties accounts payable |  | $ 159,000 | 159,000 |  | 159,000 | 159,000
Past due related parties accounts payable |  | 159,000 |  |  | 159,000 | 159,000
Hoactzin Partners, L.P. [Member] | Methane Project [Member] |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Net profits |  |  |  |  |  | 0
Methane gas sales |  |  |  |  | 0 |
Related Party [Member] | Hoactzin Partners, L.P. [Member] |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Accounts receivable-related party, allowance for doubtful accounts |  | 159,000 | 159,000 |  | 159,000 | 159,000
Accounts receivable - related parties balance |  | $ 159,000 | $ 0 |  | $ 159,000 | $ 159,000

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