Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Revenues	[1]	$ 217,410	$ 219,093	$ 650,901	$ 645,236
Operating expenses		164,089	155,388	491,115	466,669
Gross margin		53,321	63,705	159,786	178,567
Selling, general and administrative expenses		67,553	61,089	202,155	198,415
Restructuring and other related charges, net		457	319	2,614	3,365
Goodwill impairment charges		55,837	0	55,837	191,788
Operating income (loss)		(70,526)	2,297	(100,820)	(215,001)
Interest expense, net		(9,974)	(7,757)	(28,968)	(21,847)
Other expense, net		(1,760)	(655)	(3,754)	(1,292)
Loss before income taxes		(82,260)	(6,115)	(133,542)	(238,140)
(Provision) benefit for income taxes		(8,922)	(2,958)	(9,424)	15,812
Net loss		$ (91,182)	$ (9,073)	$ (142,966)	$ (222,328)
Loss per common share:
Basic (in dollars per share)		$ (2.94)	$ (0.30)	$ (4.62)	$ (7.27)
Diluted (in dollars per share)		$ (2.94)	$ (0.30)	$ (4.62)	$ (7.27)
Weighted-average number of shares outstanding:
Weighted-average number of basic shares outstanding (in shares)		30,980	30,628	30,933	30,599
Weighted-average number of diluted shares outstanding (in shares)		30,980	30,628	30,933	30,599

[1] Revenues attributable to individual countries/geographic areas are based on the country of domicile of the legal entity that performs the work.