CONDENSED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenue	$ 19,944,558	$ 20,706,460	$ 58,397,420	$ 57,471,112
Cost of revenue	15,146,080	15,794,024	44,964,256	44,337,414
Gross profit	4,798,478	4,912,436	13,433,164	13,133,698
Selling, general and administrative expenses	2,584,560	2,044,304	7,192,159	6,210,380
Income from operations	2,213,918	2,868,132	6,241,005	6,923,318
Interest expense	574,765	402,619	1,438,862	1,258,857
Income before provision for income taxes	1,639,153	2,465,513	4,802,143	5,664,461
Provision for income taxes	311,000	770,000	960,000	1,954,000
Net income	1,328,153	1,695,513	3,842,143	3,710,461
Other comprehensive income (loss), net of tax - Change in unrealized (gain) loss on interest rate swap	20,600	(2,300)	14,800	1,900
Comprehensive income	$ 1,348,753	$ 1,693,213	$ 3,856,943	$ 3,712,361
Income per common share - basic (in dollars per share)	$ 0.15	$ 0.19	$ 0.43	$ 0.42
Income per common share - diluted (in dollars per share)	$ 0.15	$ 0.19	$ 0.43	$ 0.42
Shares used in computing income per common share:
Basic (in shares)	8,952,979	8,846,507	8,926,734	8,820,379
Diluted (in shares)	8,977,075	8,872,810	8,951,640	8,841,397