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Litigation (Details) - USD ($) | Mar. 31, 2016 | Dec. 31, 2015 | Mar. 31, 2015 | Mar. 12, 2015 | Aug. 31, 2011
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Loss Contingencies [Line Items] |  |  |  |  |
Potential liabilities related to litigation and environmental matters | $ 19,000,000 | $ 19,500,000 | $ 25,800,000 |  |
Litigation related to construction materials [Member] |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |
Loss contingency, estimate of possible loss |  |  |  |  | $ 3,700,000
Additional amount per day of potential penalties |  |  |  |  | $ 5,000
Litigation related to construction services [Member] |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |
Damage repair estimate |  |  |  | $ 21,000,000 |

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