Accounting Standards - Effects of Adoption of ASC 606 and ASC 842 on Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	$ 135,185		$ 132,603		$ 273,957	$ 266,350
Cost of revenue	114,850		114,908		235,398	229,031
Gross profit	20,335		17,695		38,559	37,319
Selling, general and administrative expenses	13,752		17,079		30,552	33,124
Amortization of intangibles	274		175		417	350
Total operating expenses	14,026		17,254		30,969	33,474
Operating income	6,309		441		7,590	3,845
Interest expense, net	(2,137)		(1,597)		(4,295)	(2,430)
Gain (loss) on disposition of property and equipment	(13)		9		17	21
Loss on debt extinguishment	0		(513)		0	(513)
Loss on change in fair value of warrant liability	(102)		(103)		59	(103)
Total unallocated amounts	(2,252)		(2,204)		(4,219)	(3,025)
Income (loss) before income taxes	4,057		(1,763)		3,371	820
Income tax provision (benefit)	1,110		(474)		476	261
Net income (loss)	$ 2,947	$ (52)	(1,289)	$ 1,847	$ 2,895	559
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue			0			0
Cost of revenue			0			0
Gross profit			0			0
Selling, general and administrative expenses			0			0
Amortization of intangibles			0			0
Total operating expenses			0			0
Operating income			0			0
Interest expense, net			0			0
Gain (loss) on disposition of property and equipment			0			0
Loss on debt extinguishment			0			0
Loss on change in fair value of warrant liability			0			0
Total unallocated amounts			0			0
Income (loss) before income taxes			0			0
Income tax provision (benefit)			0			0
Net income (loss)			0			0
Construction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue			104,759			209,219
Cost of revenue			94,076			185,620
Construction | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue			0			0
Cost of revenue			0			0
Service
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue			27,844			57,131
Cost of revenue			20,832			43,411
Service | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue			0			0
Cost of revenue			0			0
Calculated under Revenue Guidance in Effect before Topic 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue			132,753			266,704
Cost of revenue			115,352			229,270
Gross profit			17,401			37,434
Selling, general and administrative expenses			17,079			33,124
Amortization of intangibles			175			350
Total operating expenses			17,254			33,474
Operating income			147			3,960
Interest expense, net			(1,597)			(2,430)
Gain (loss) on disposition of property and equipment			9			21
Loss on debt extinguishment			(513)			(513)
Loss on change in fair value of warrant liability			(103)			(103)
Total unallocated amounts			(2,204)			(3,025)
Income (loss) before income taxes			(2,057)			935
Income tax provision (benefit)			(553)			293
Net income (loss)			(1,504)			642
Calculated under Revenue Guidance in Effect before Topic 606 | Construction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue			104,925			209,599
Cost of revenue			94,503			185,864
Calculated under Revenue Guidance in Effect before Topic 606 | Service
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue			27,828			57,105
Cost of revenue			20,849			43,406
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue			(150)			(354)
Cost of revenue			(444)			(239)
Gross profit			294			(115)
Selling, general and administrative expenses			0			0
Amortization of intangibles			0			0
Total operating expenses			0			0
Operating income			294			(115)
Interest expense, net			0			0
Gain (loss) on disposition of property and equipment			0			0
Loss on debt extinguishment			0			0
Loss on change in fair value of warrant liability			0			0
Total unallocated amounts			0			0
Income (loss) before income taxes			294			(115)
Income tax provision (benefit)			79			(32)
Net income (loss)			215			(83)
Difference between Revenue Guidance in Effect before and after Topic 606 | Construction | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue			(166)			(380)
Cost of revenue			(427)			(244)
Difference between Revenue Guidance in Effect before and after Topic 606 | Service | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue			16			26
Cost of revenue			$ (17)			$ 5