Quarterly Financial Data (Unaudited) - Additional Informations (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
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)
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
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
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
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)
Depreciation and amortization				3,681				3,776	6,984	7,674	10,865	11,676	15,514	15,270	15,196
Deferred income taxes				2,298				2,181	2,263	6,396	1,840	8,369	1,562	5,031	7,709
Prepaid expenses				(2,272)				(1,496)	(2,501)	(2,507)	(2,607)	(2,126)	(1,793)	(2,292)	179
Purchases of property, plant and equipment				(5,580)				(1,716)	(12,800)	(5,158)	(18,743)	(9,823)	(24,002)	(14,150)	(13,458)
Depreciation expense													13,562	13,971	13,875
Accounts receivable				(26,356)				(34,884)	(26,552)	(47,306)	(25,454)	(50,389)	$ 11,954	(34,987)	(13,792)
Restatement Adjustments
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)
Property, plant and equipment, net		(1,414)	(826)	(961)	(998)	(1,035)	(1,072)	(1,109)	(826)	(1,072)	(1,414)	(1,035)		(998)
Provision for income taxes		(420)	(316)	(327)	(236)	(393)	(157)	(123)	(643)	(280)	(1,063)	(673)		(909)	(283)
Cost of revenues		1,760	1,347	1,471	1,020	1,699	681	532	2,818	1,213	4,578	2,912		3,932	847
Net (loss) income		(1,340)	(1,031)	(1,144)	(784)	(1,306)	(524)	(409)	(2,175)	(933)	(3,515)	(2,239)		(3,023)	(564)
Depreciation and amortization				(37)				(37)	(74)	(74)	(111)	(111)		(148)	(148)
Deferred income taxes				(327)				(123)	(643)	(280)	(1,063)	(673)		(909)	(283)
Prepaid expenses				1,508				569	2,990	1,259	4,851	2,336		3,393	993
Purchases of property, plant and equipment				0				0	(98)	0	527	0		0	0
Accounts receivable				0				0	0	28	(689)	687		687	2
Understatement of cost of revenues and impacted balance sheet accounts
Net (loss) income								(400)		(1,000)		(2,300)
Deferred income taxes								(100)		(300)		(700)
Prepaid expenses								(500)		(1,300)		(2,300)
Accounts receivable												(700)
Understatement of cost of revenues and impacted balance sheet accounts | Restatement Adjustments
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)
Property, plant and equipment, net		(500)	100						100		(500)
Provision for income taxes		(400)	(300)		(200)	(400)	(200)	(100)		(300)		(700)		(1,000)	(200)
Cost of revenues		1,800	1,400	1,500	1,000	1,700	700	500	2,900	1,300	4,700	3,000		4,100	1,000
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)
Prepaid expenses				1,500					(3,000)		4,900			3,400	1,000
Purchases of property, plant and equipment									(100)		500
Accounts receivable											(700)			700
Property, plant and equipment, net error correction
Net (loss) income										100		100
Depreciation expense										(100)		(100)
Property, plant and equipment, net error correction | Restatement Adjustments
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)
Property, plant and equipment, net		$ (900)	$ (900)	$ (1,000)		$ (1,000)	$ (1,100)	$ (1,100)	(900)	(1,100)	(900)	(1,000)
Provision for income taxes															(100)
Cost of revenues										(100)		(100)		(100)	(100)
Net (loss) income									100	$ 100	100	$ 100		100	200
Depreciation and amortization											$ (100)
Deferred income taxes															(100)
Depreciation expense									$ (100)					$ (100)	$ (100)