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Construction Joint Ventures - Narrative (Details) - USD ($) $ in Thousands | Sep. 30, 2017 | Dec. 31, 2016
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Joint Ventures |  |
Schedule of Equity Method Investments [Line Items] |  |
Sterling’s noncontrolling interest in backlog | $ 26,659 | $ 52,992
Granite Construction Corporation |  |
Schedule of Equity Method Investments [Line Items] |  |
Equity method investment, ownership percentage | 50.00% |

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