Restatement of Previously Issued Consolidated Financial Statements - Additional Information (Details) - USD ($) $ 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	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Accounts receivable, net of allowances	$ 115,099	$ 153,190	$ 157,193	$ 158,327	$ 133,935	$ 150,507	$ 150,576	$ 141,821	$ 157,193	$ 150,576	$ 153,190	$ 150,507	$ 115,099	$ 133,935
Other current assets	18,490	14,897	14,632	15,001	12,080	10,446	11,367	16,461	14,632	11,367	14,897	10,446	18,490	12,080
Deferred income taxes, net	14,654	14,117	13,387	14,243	16,341	12,499	14,303	18,447	13,387	14,303	14,117	12,499	14,654	16,341
Retained deficit	60,307	52,773	59,953	66,099	76,013	84,110	95,387	108,058	59,953	95,387	52,773	84,110	60,307	76,013		$ 115,233
Machinery and equipment, gross	186,511				173,771								186,511	173,771
Accumulated depreciation	(154,939)				(142,560)								(154,939)	(142,560)
Cost of revenue	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
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 (loss) income	(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)
Deferred income taxes				2,298				2,181	2,263	6,396	1,840	8,369	1,562	5,031	7,709
Increase (decrease) in accounts receivable				(26,356)				(34,884)	(26,552)	(47,306)	(25,454)	(50,389)	11,954	(34,987)	(13,792)
Prepaid expenses				(2,272)				(1,496)	(2,501)	(2,507)	(2,607)	(2,126)	(1,793)	(2,292)	179
Depreciation expense													13,562	13,971	13,875
Property, plant and equipment, net	73,686	71,645	69,832	65,167	64,101	61,965	61,145	62,291	69,832	61,145	71,645	61,965	73,686	64,101
Stockholders' equity	(128,688)	(130,788)	(128,885)	(120,065)	(109,596)	(100,657)	(91,189)	(83,572)	(128,885)	(91,189)	(130,788)	(100,657)	(128,688)	(109,596)	(72,323)	(65,835)
Assets, current	$ 255,972	296,976	325,259	324,956	309,287	311,673	297,726	290,827	325,259	297,726	296,976	311,673	255,972	309,287
Payments to Acquire Property, Plant, and Equipment				(5,580)				(1,716)	(12,800)	(5,158)	(18,743)	(9,823)	$ (24,002)	(14,150)	(13,458)
Understatement of cost of revenues and impacted balance sheet accounts
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net (loss) income								(400)		(1,000)		(2,300)
Deferred income taxes								(100)		(300)		(700)
Increase (decrease) in accounts receivable												(700)
Prepaid expenses								(500)		(1,300)		(2,300)
Property, plant and equipment, net error correction
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net (loss) income										100		100
Depreciation expense										(100)		(100)
Restatement Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Accounts receivable, net of allowances		0	(689)	(689)	(689)	(689)	(30)	(2)	(689)	(30)	0	(689)		(689)
Other current assets		(9,599)	(7,738)	(6,256)	(4,748)	(3,691)	(2,614)	(1,924)	(7,738)	(2,614)	(9,599)	(3,691)		(4,748)
Deferred income taxes, net		2,056	1,636	1,320	993	757	364	207	1,636	364	2,056	757		993
Retained deficit		8,957	7,617	6,586	5,442	4,658	3,352	2,828	7,617	3,352	8,957	4,658		5,442	2,400	1,855
Machinery and equipment, gross					(2,219)									(2,219)
Accumulated depreciation					1,221									1,221
Cost of revenue		1,760	1,347	1,471	1,020	1,699	681	532	2,818	1,213	4,578	2,912		3,932	847
Provision for income taxes		(420)	(316)	(327)	(236)	(393)	(157)	(123)	(643)	(280)	(1,063)	(673)		(909)	(283)
Net (loss) income		(1,340)	(1,031)	(1,144)	(784)	(1,306)	(524)	(409)	(2,175)	(933)	(3,515)	(2,239)		(3,023)	(564)
Deferred income taxes				(327)				(123)	(643)	(280)	(1,063)	(673)		(909)	(283)
Increase (decrease) in accounts receivable				0				0	0	28	(689)	687		687	2
Prepaid expenses				1,508				569	2,990	1,259	4,851	2,336		3,393	993
Property, plant and equipment, net		(1,414)	(826)	(961)	(998)	(1,035)	(1,072)	(1,109)	(826)	(1,072)	(1,414)	(1,035)		(998)
Stockholders' equity		8,957	7,617	6,586	5,442	4,658	3,352	2,828	7,617	3,352	8,957	4,658		5,442	2,419	$ 1,855
Assets, current		(9,599)	(8,427)	(6,945)	(5,437)	(4,380)	(2,644)	(1,926)	(8,427)	(2,644)	(9,599)	(4,380)		(5,437)
Payments to Acquire Property, Plant, and Equipment				0				0	(98)	0	527	0		0	0
Restatement Adjustments | Understatement of cost of revenues and impacted balance sheet accounts
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Accounts receivable, net of allowances			(700)	(700)	(700)	(700)			(700)			(700)		(700)
Other current assets		(9,600)	(7,700)	(6,300)	(4,700)	(3,700)	(2,600)	(1,900)	(7,700)	(2,600)	(9,600)	(3,700)		(4,700)
Deferred income taxes, net		2,300	1,900	1,600	1,300	1,000	600	400	1,900	600	2,300	1,000		1,300
Retained deficit		7,800	6,400	5,300	4,100	3,400	2,000	1,500	6,400	2,000	7,800	3,400		4,100
Cost of revenue		1,800	1,400	1,500	1,000	1,700	700	500	2,900	1,300	4,700	3,000		4,100	1,000
Provision for income taxes		(400)	(300)		(200)	(400)	(200)	(100)		(300)		(700)		(1,000)	(200)
Net (loss) income		(1,300)	(1,000)	(1,100)	(800)	(1,300)	(500)	(400)	(2,200)	(1,000)	(3,600)	(2,300)		(3,100)	(800)
Deferred income taxes				(300)					(700)		(1,100)			(900)	(200)
Increase (decrease) in accounts receivable											(700)			700
Prepaid expenses				1,500					(3,000)		4,900			3,400	1,000
Property, plant and equipment, net		(500)	100						100		(500)
Payments to Acquire Property, Plant, and Equipment									(100)		500
Restatement Adjustments | Property, plant and equipment, net error correction
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Deferred income taxes, net		(300)	(300)	(300)	(300)	(300)	(200)	(200)	(300)	(200)	(300)	(300)		(300)
Retained deficit		1,200	1,200	1,200	1,300	1,300	1,300	1,300	1,200	1,300	1,200	1,300		1,300
Machinery and equipment, gross					(2,200)									(2,200)
Accumulated depreciation					$ 1,200									1,200
Cost of revenue										(100)		(100)		(100)	(100)
Provision for income taxes															(100)
Net (loss) income									100	100	100	100		100	200
Deferred income taxes															(100)
Depreciation expense									(100)					$ (100)	$ (100)
Property, plant and equipment, net		$ (900)	$ (900)	$ (1,000)		$ (1,000)	$ (1,100)	$ (1,100)	$ (900)	$ (1,100)	$ (900)	$ (1,000)