Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Revenues	[1]	$ 238,873	$ 189,304	$ 433,491	$ 426,143
Operating expenses		176,109	131,928	327,026	311,281
Gross margin		62,764	57,376	106,465	114,862
Selling, general and administrative expenses		68,478	58,882	134,602	137,326
Restructuring and other related charges, net		280	2,860	2,157	3,046
Goodwill impairment charge		0	0	0	191,788
Operating loss		(5,994)	(4,366)	(30,294)	(217,298)
Interest expense, net		(9,598)	(7,314)	(18,994)	(14,090)
Other expense, net		(1,044)	(165)	(1,994)	(637)
Loss before income taxes		(16,636)	(11,845)	(51,282)	(232,025)
(Provision) benefit for income taxes		(857)	(1,683)	(502)	18,770
Net loss		$ (17,493)	$ (13,528)	$ (51,784)	$ (213,255)
Loss per common share:
Basic (in dollars per share)		$ (0.57)	$ (0.44)	$ (1.68)	$ (6.97)
Diluted (in dollars per share)		$ (0.57)	$ (0.44)	$ (1.68)	$ (6.97)
Weighted-average number of shares outstanding:
Weighted-average number of basic shares outstanding (in shares)		30,940	30,628	30,909	30,584
Weighted-average number of diluted shares outstanding (in shares)		30,940	30,628	30,909	30,584

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