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Commitments and Contingencies (Narrative) (Details) $ in Thousands |  |  |  | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | ---
Jul. 29, 2016 defendant | Feb. 09, 2016 defendant | Mar. 11, 1997 | Jun. 30, 2016 USD ($) | Jun. 30, 2017 USD ($) well | Jul. 29, 2016 claim | Jun. 30, 2016 USD ($) | Dec. 31, 1997 USD ($) well
Commitments [Line Items] |  |  |  |  |  |  |  |
Plugging and abandonment escrow account on the WCBB properties (Note 10) |  |  |  |  | $ 3,100 |  |  |
Number of claims filed | claim |  |  |  |  |  | 2 |  |
Judicial District Court for the Parish of Cameron |  |  |  |  |  |  |  |
Commitments [Line Items] |  |  |  |  |  |  |  |
Number of defendants | defendant |  | 26 |  |  |  |  |  |
Judicial District Court for the Parish of Vermillion |  |  |  |  |  |  |  |
Commitments [Line Items] |  |  |  |  |  |  |  |
Number of defendants | defendant | 40 |  |  |  |  |  |  |
WCBB |  |  |  |  |  |  |  |
Commitments [Line Items] |  |  |  |  |  |  |  |
Purchasing remaining percent interest In oil and gas property, percent |  |  |  |  |  |  |  | 50.00%
Payments held for restricted cash |  |  |  |  |  |  |  | $ 18
Significant plugging commitment minimum number of wells to be plugged | well |  |  |  |  |  |  |  | 20
Tenure of minimum wells to be plugged |  |  | 20 years |  |  |  |  |
Number of wells plugged | well |  |  |  |  | 513 |  |  |
Loss on long-term purchase commitment | Muskie Proppant LLC |  |  |  |  |  |  |  |
Commitments [Line Items] |  |  |  |  |  |  |  |
Long-term purchase commitment, accrued damages year to date |  |  |  | $ 700 | $ 0 |  | $ 2,000 |
Minimum |  |  |  |  |  |  |  |
Commitments [Line Items] |  |  |  |  |  |  |  |
Operating lease, term |  |  |  |  | 1 year |  |  |

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