Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenues	$ 189,485	$ 225,399	$ 243,190	$ 243,164	$ 223,602	$ 225,010	$ 233,391	$ 215,734	$ 486,354	$ 449,125	$ 711,753	$ 674,135	$ 901,238	$ 897,737	$ 755,231
Cost of revenues	179,317	195,955	210,754	210,075	194,354	194,532	198,487	185,444	420,829	383,931	616,784	578,463	796,101	772,817	664,360
Gross Profit	10,168	29,444	32,436	33,089	29,248	30,478	34,904	30,290	65,525	65,194	94,969	95,672	105,137	124,920	90,871
Selling, general and administrative expenses	13,571	17,531	16,248	15,199	15,503	15,613	14,349	15,214	31,447	29,563	48,978	45,176	62,549	60,679	59,547
Amortization expense	872	437	322	321	320	321	327	332	643	659	1,080	980	1,952	1,300	1,320
Operating Income	(4,275)	11,476	15,866	17,569	13,425	14,544	20,228	14,744	33,435	34,972	44,911	49,516	40,636	62,941	30,004
Other (expense) income													(2,225)	1,311	1,943
Interest expense	3,394	3,800	7,490	4,396	4,960	3,442	3,213	1,750	11,886	4,963	15,686	8,405	16,855	14,676	19,149
Income before provision for income taxes	(7,669)	7,676	8,376	13,173	8,465	11,102	17,015	12,994	21,549	30,009	29,225	41,111	21,556	49,576	12,798
Provision for income taxes	(135)	496	2,230	3,187	368	(175)	4,344	3,550	5,417	7,894	5,913	7,719	5,778	8,087	15,067
Net income (loss)	$ (7,534)	$ 7,180	$ 6,146	$ 9,986	$ 8,097	$ 11,277	$ 12,671	$ 9,444	$ 16,132	$ 22,115	$ 23,312	$ 33,392	$ 15,778	$ 41,489	$ (2,269)
Earnings (loss) per common share
Basic (in dollars per share)	$ (0.24)	$ 0.23	$ 0.20	$ 0.33	$ 0.27	$ 0.37	$ 0.42	$ 0.31	$ 0.53	$ 0.73	$ 0.76	$ 1.11	$ 0.52	$ 1.37	$ (0.08)
Diluted (in dollars per share)	$ (0.24)	$ 0.23	$ 0.20	$ 0.33	$ 0.26	$ 0.37	$ 0.42	$ 0.31	$ 0.52	$ 0.72	$ 0.76	$ 1.09	$ 0.51	$ 1.36	$ (0.08)
Weighted average shares outstanding
Basic (in shares)	30,758	30,581	30,547	30,513	30,447	30,219	30,219	30,219	30,530	30,219	30,547	30,219	30,602	30,277	29,942
Diluted (in shares)	30,758	30,852	30,824	30,694	30,543	30,638	30,513	30,574	30,731	30,543	30,829	30,575	30,823	30,587	29,942