Accounting Standards - Effects of Adoption of ASC 606 and ASC 842 on Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	$ 138,772	$ 133,746
Cost of revenue	120,548	114,123
Gross profit	18,224	19,623
Selling, general and administrative expenses	16,799	16,045
Amortization of intangibles	143	175
Total operating expenses	16,942	16,220
Operating income	1,282	3,403
Interest expense, net	(2,158)	(833)
Gain on disposition of property and equipment	29	12
Total unallocated amounts	(1,968)	(821)
Income (loss) before income taxes	(686)	2,582
Income tax provision (benefit)	(634)	735
Net income (loss)	$ (52)	1,847
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 expenses		0
Amortization of intangibles		0
Total operating expenses		0
Operating income		0
Interest expense, net		0
Gain on disposition of property and equipment		0
Total unallocated amounts		0
Income (loss) before income taxes		0
Income tax provision (benefit)		0
Net income (loss)		0
Construction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		104,459
Cost of revenue		91,544
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		29,287
Cost of revenue		22,579
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		133,951
Cost of revenue		113,918
Gross profit		20,033
Selling, general and administrative expenses		16,045
Amortization of intangibles		175
Total operating expenses		16,220
Operating income		3,813
Interest expense, net		(833)
Gain on disposition of property and equipment		12
Total unallocated amounts		(821)
Income (loss) before income taxes		2,992
Income tax provision (benefit)		846
Net income (loss)		2,146
Calculated under Revenue Guidance in Effect before Topic 606 | Construction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		104,674
Cost of revenue		91,361
Calculated under Revenue Guidance in Effect before Topic 606 | Service
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		29,277
Cost of revenue		22,557
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		(205)
Cost of revenue		205
Gross profit		(410)
Selling, general and administrative expenses		0
Amortization of intangibles		0
Total operating expenses		0
Operating income		(410)
Interest expense, net		0
Gain on disposition of property and equipment		0
Total unallocated amounts		0
Income (loss) before income taxes		(410)
Income tax provision (benefit)		(111)
Net income (loss)		(299)
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		(215)
Cost of revenue		183
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		10
Cost of revenue		$ 22