Consolidated 50% Owned Subsidiaries, including Variable Interest Entities ("VIE") Consolidated 50% Owned Subsidiaries, including Variable Interest Entities - Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Schedule of Equity Method Investments [Line Items]
Revenues	$ 222,492	$ 153,416
Operating income	6,679	(1,788)
Net income (loss) attributable to Sterling common stockholders	2,489	(2,257)
Variable Interest Entity, Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Revenues	40,175	23,285
Operating income	1,107	394
Net income (loss) attributable to Sterling common stockholders	$ 554	$ 195

Consolidated 50% Owned Subsidiaries, including Variable Interest Entities ("VIE") Consolidated 50% Owned Subsidiaries, including Variable Interest Entities - Statement of Operations (Details) - USD ($)
$ in Thousands

3 Months Ended

Mar. 31, 2018

Mar. 31, 2017

Schedule of Equity Method Investments [Line Items]

Revenues

$ 222,492

$ 153,416

Operating income

6,679

(1,788)

Net income (loss) attributable to Sterling common stockholders

2,489