CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Statement [Abstract]
Net revenues	$ 261,287	$ 237,470
Material costs	85,592	75,170
Personnel costs	101,675	89,880
Other operating costs	36,168	31,498
General and administrative expenses	32,442	30,903
Depreciation and amortization	7,955	7,998
(Loss) income from operations	(2,545)	2,021
Interest expense, net	7,385	7,340
Non-service defined benefit plan expense	160	167
Loss before income taxes	(10,090)	(5,486)
Benefit for income taxes	(2,113)	(2,156)
Net loss	$ (7,977)	$ (3,330)
Basic and diluted per common share data:
Basic loss per share (in dollars per share)	$ (0.21)	$ (0.09)
Diluted loss per share (in dollars per share)	$ (0.21)	$ (0.09)
Weighted average shares used to compute basic loss per share (in shares)	38,802,420	38,268,332
Weighted average shares used to compute diluted loss per share (in shares)	38,802,420	38,268,332