Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Income Statement [Abstract]
Revenues	$ 1,163,314	$ 1,246,929		$ 1,200,211
Operating expenses	835,570	918,673		890,212
Gross margin	327,744	328,256		309,999
Selling, general and administrative expenses	328,214	360,692		348,391
Restructuring and other related charges, net (see Note 16)	1,676	6,727		2,651
Gain on revaluation of contingent consideration	0	(202)		(1,174)
Goodwill impairment loss (see Note 1)	0	0		75,241
Operating loss	(2,146)	(38,961)		(115,110)
Interest expense, net	29,713	30,875		21,487
Write-off of deferred loan costs	279	0		1,244
Loss (gain) on convertible debt embedded derivative (see Note 9)	0	24,783		(818)
Other (income) expense, net	715	(410)		510
Loss before income taxes	(32,853)	(94,209)		(137,533)
Less: Benefit for income taxes (see Note 8)	(436)	(31,063)		(53,078)
Net loss	$ (32,417)	$ (63,146)	[1]	$ (84,455)
Earnings (Loss) per common share:
Net income (loss) per share: Basic (in USD per share)	$ (1.07)	$ (2.10)	[1]	$ (2.83)
Net income (loss) per share: Diluted (in USD per share)	$ (1.07)	$ (2.10)	[1]	$ (2.83)

[1] Income (loss) from continuing operations, net income (loss) and the related earnings (loss) per share amounts for each of the quarters in 2018 are revised from those originally reported to correct errors in income tax expense (benefit) associated with the measurement of valuation allowances on deferred tax assets. Based on an analysis of quantitative and qualitative factors, the Company determined the related impacts were not material to its previously filed interim consolidated financial statements, and therefore, amendments of previously filed reports are not required.