Construction Joint Ventures - Income Statement Information (Details) - Joint Ventures - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Schedule of Equity Method Investments [Line Items]
Revenues	$ 26,846	$ 31,384
Income before tax	2,157	1,969
Sterling’s noncontrolling interest:
Revenues	13,082	15,684
Income before tax	$ 1,049	$ 984

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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