Accounting Standards Effects of Adoption of ASC 606 and ASC 842 on Statement of Operations (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		$ 553,334,000	$ 546,526,000
Cost of revenue		481,457,000	487,095,000
Gross profit		71,877,000	59,431,000
Selling, general and administrative		63,168,000	57,089,000
Amortization of intangibles		642,000	1,272,000
Total operating expenses		63,810,000	58,361,000
Operating income		8,067,000	1,070,000
Impairment of goodwill		(4,359,000)	0
Interest income (expense), net		(6,285,000)	(3,305,000)
Loss on debt extinguishment		(513,000)	0
Gain on change in fair value of warrant liability		588,000	0
Gain on embedded derivative		388,000	0
Gain (loss) on sale of property and equipment		57,000	90,000
Total other expenses		(10,124,000)
Loss before income taxes		(2,057,000)	(2,480,000)
Income tax benefit		(282,000)	(635,000)
Net loss		(1,775,000)	$ (1,845,000)
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		0
Cost of revenue		0
Gross profit		0
Selling, general and administrative		0
Amortization of intangibles		0
Total operating expenses		0
Operating income		0
Impairment of goodwill		0
Interest income (expense), net		0
Loss on debt extinguishment		0
Gain on change in fair value of warrant liability		0
Gain on embedded derivative		0
Gain (loss) on sale of property and equipment		0
Total other expenses		0
Loss before income taxes		0
Income tax benefit		0
Net loss		0
Construction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		438,196,000
Cost of revenue		394,703,000
Impairment of goodwill		(4,359,000)
Construction | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		0
Cost of revenue		0
Service
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		115,138,000
Cost of revenue		86,754,000
Impairment of goodwill	$ 0	0
Service | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		0
Cost of revenue		0
Calculated under Revenue Guidance in Effect before Topic 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		553,401,000
Cost of revenue		482,143,000
Gross profit		71,258,000
Selling, general and administrative		63,168,000
Amortization of intangibles		642,000
Total operating expenses		63,810,000
Operating income		7,448,000
Impairment of goodwill		(4,359,000)
Interest income (expense), net		(6,285,000)
Loss on debt extinguishment		(513,000)
Gain on change in fair value of warrant liability		588,000
Gain on embedded derivative		388,000
Gain (loss) on sale of property and equipment		57,000
Total other expenses		(10,124,000)
Loss before income taxes		(2,676,000)
Income tax benefit		(449,000)
Net loss		(2,227,000)
Calculated under Revenue Guidance in Effect before Topic 606 | Construction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		438,179,000
Cost of revenue		395,272,000
Calculated under Revenue Guidance in Effect before Topic 606 | Service
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		115,222,000
Cost of revenue		86,871,000
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		(67,000)
Cost of revenue		(686,000)
Gross profit		619,000
Selling, general and administrative		0
Amortization of intangibles		0
Total operating expenses		0
Operating income		619,000
Impairment of goodwill		0
Interest income (expense), net		0
Loss on debt extinguishment		0
Gain on change in fair value of warrant liability		0
Gain on embedded derivative		0
Gain (loss) on sale of property and equipment		0
Total other expenses		0
Loss before income taxes		619,000
Income tax benefit		167,000
Net loss		452,000
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		17,000
Cost of revenue		(569,000)
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		(84,000)
Cost of revenue		$ (117,000)