Operating Segments - Segment Reporting Information (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenue		$ 553,334,000	$ 546,526,000
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
Operating income		8,067,000	1,070,000
Impairment of goodwill		(4,359,000)	0
Interest expense		(6,285,000)	(3,305,000)
Loss on debt modification		0	(335,000)
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 unallocated amounts		(5,765,000)	(3,550,000)
Loss before income taxes		(2,057,000)	(2,480,000)
Depreciation and amortization		6,286,000	5,683,000
Construction
Segment Reporting Information [Line Items]
Revenue		438,196,000
Impairment of goodwill		(4,359,000)
Service
Segment Reporting Information [Line Items]
Revenue		115,138,000
Impairment of goodwill	$ 0	0
Operating Segments | Construction
Segment Reporting Information [Line Items]
Revenue		438,196,000	438,229,000
Gross profit		43,493,000	36,721,000
Selling, general and administrative		28,356,000	27,307,000
Depreciation and amortization		3,738,000	2,812,000
Operating Segments | Service
Segment Reporting Information [Line Items]
Revenue		115,138,000	108,297,000
Gross profit		28,384,000	22,710,000
Selling, general and administrative		17,367,000	15,003,000
Depreciation and amortization		997,000	749,000
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Selling, general and administrative		17,445,000	14,779,000
Depreciation and amortization		$ 1,551,000	$ 2,122,000