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Equity Method Investments (Narrative) (Details) - USD ($) $ in Thousands |  | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Nov. 03, 2016 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Nov. 02, 2016 | Oct. 01, 2014 | Sep. 30, 2014
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Cash distributions | $ 1,800 | $ 3,977 |  | $ 8,109 |  |  |
Asset impairment charge |  | $ 16,560 |  |  |  |  |
Savoy [Member] |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Equity method investment ownership percentage | 30.60% | 30.60% |  |  | 40.80% | 40.80% | 45.00%
Cash distributions paid |  |  |  | 3,200 |  |  |
Cash distributions |  | $ 3,600 |  | $ 8,100 |  |  |
Sunrise Energy [Member] |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Equity method investment ownership percentage |  | 50.00% |  |  |  |  |
Savoy [Member] |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Cash recieved by equity investment for sale of equity | $ 9,500 |  |  |  |  |  |
Cash distributions | $ 4,400 |  |  |  |  |  |
Asset impairment charge |  | $ 2,000 | $ 2,600 |  |  |  |
Lubar Equity Fund, LLC [Member] | Savoy [Member] |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Equity method investment ownership percentage | 25.00% |  |  |  |  |  |

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