Construction Joint Ventures - Income Statement Information (Details) - Joint Ventures - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Schedule of Equity Method Investments [Line Items]
Revenues	$ 40,875	$ 32,190	$ 127,565	$ 89,010
Operating income	3,588	1,728	14,401	7,324
Sterling’s noncontrolling interest:
Revenues	20,119	12,820	61,774	41,739
Operating income	$ 1,769	$ 858	$ 5,869	$ 3,716

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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