Concentration of Risk and Enterprise-Wide Disclosures (Tables)

9 Months Ended

Sep. 30, 2021

Trade and contract retainage receivables

Concentration Risk [Line Items]

Schedules of concentration of risk, by risk factor

	September 30, 2021				December 31, 2020
Federal Government	$	3,028	2	%	$	4,826	4	%
State Governments		418	1	%		—	-	%
Local Governments		13,927	11	%		17,823	13	%
Private Companies		106,110	86	%		110,616	83	%
Gross receivables		123,483	100	%		133,265	100	%
Allowance for credit losses		(323)				(411)
Net receivables	$	123,160			$	132,854

Contract revenues

Concentration Risk [Line Items]

Schedules of concentration of risk, by risk factor

	Three months ended September 30,								Nine months ended September 30,
	2021		%		2020		%		2021		%		2020		%
Federal Government	$	14,716	11	%	$	16,499	9	%	$	39,825	9	%	$	32,720	6	%
State Governments		400	-	%		6,322	3	%		814	-	%		27,646	5	%
Local Government		22,765	16	%		54,316	29	%		94,857	22	%		158,176	29	%
Private Companies		102,026	73	%		112,296	59	%		303,595	69	%		321,224	60	%
Total contract revenues	$	139,907	100	%	$	189,433	100	%	$	439,091	100	%	$	539,766	100	%