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Litigation (Details) (USD $) |  |  |  |  | 0 Months Ended |
--- | --- | --- | --- | --- | --- | ---
Sep. 30, 2014 | Dec. 31, 2013 | Sep. 30, 2013 | Aug. 31, 2011 Litigation related to construction materials [Member] | Aug. 06, 2012 Former employee litigation [Member] | Oct. 31, 2010 Natural gas gathering operations [Member]
Loss Contingencies [Line Items] |  |  |  |  |  |
Potential liabilities related to litigation and environmental matters | $ 31,900,000 | $ 29,500,000 | $ 30,800,000 |  |  |
Loss contingency, estimate of possible loss |  |  |  | 3,700,000 |  |
Additional amount per day of potential penalties |  |  |  | 5,000 |  |
Plaintiffs request compensatory damages |  |  |  |  | 23,800,000 |
Arbitration award |  |  |  |  |  | $ 26,600,000

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