Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net loss	$ (63,146)	$ (84,455)	$ (12,676)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	64,862	52,143	48,673
Write-off of deferred loan costs	0	1,244	0
Amortization of deferred loan costs and debt discount	7,022	3,085	541
Provision for doubtful accounts	11,662	7,097	6,336
Foreign currency loss (gain)	1,712	499	(93)
Deferred income taxes	(31,734)	(66,246)	(4,236)
(Gain) loss on revaluation of contingent consideration	(202)	(1,174)	2,184
Gain (loss) on asset disposal	(552)	553	1,540
Loss (gain) on convertible debt embedded derivative (see Note 10)	24,783	(818)	0
Goodwill impairment loss	0	75,241	0
Non-cash compensation cost	12,256	7,876	7,313
Other, net	(3,762)	(3,789)	(1,182)
(Increase) decrease (net of the effects of acquisitions):
Receivables	15,386	(39,820)	16,518
Inventory	(21)	614	2,119
Prepaid expenses and other current assets	6,933	6,642	(163)
Increase (decrease) (net of the effects of acquisitions):
Accounts payable	(8,994)	6,424	8,361
Other accrued liabilities	9,168	14,896	(2,346)
Income taxes	(3,514)	6,260	6,675
Net cash provided by (used) in operating activities	41,859	(13,728)	79,564
Cash flows from investing activities:
Capital expenditures	(27,164)	(36,798)	(45,812)
Net proceeds from sale of discontinued operations	0	0	13,295
Business acquisitions, net of cash acquired	0	0	(48,382)
Proceeds from disposal of assets	2,580	3,259	4,232
Other	(443)	(457)	827
Net cash used in investing activities	(25,027)	(33,996)	(75,840)
Cash flows from financing activities:
Net (payments) borrowings under revolving credit agreement	(19,690)	(23,006)	15,996
Payments under term loan	0	(170,000)	(20,000)
Issuance of convertible debt, net of issuance costs	0	222,311	0
Deferred consideration payments	0	0	(694)
Contingent consideration payments	(1,106)	(1,278)	(1,816)
Purchase of treasury stock	0	0	(7,593)
Debt issuance costs on Credit Facility	(855)	(1,938)	(801)
Corporate tax effect from share-based payment arrangements	0	0	(535)
Exercise of stock options	0	450	5,903
Issuance of common stock, net of issuance costs	0	0	5,243
Payments related to withholding tax for share-based payment arrangements	(1,390)	(947)	(1,709)
Net cash (used in) provided by financing activities	(23,041)	25,592	(6,006)
Effect of exchange rate changes on cash	(2,055)	2,468	(1,327)
Net decrease in cash and cash equivalents	(8,264)	(19,664)	(3,609)
Cash and cash equivalents at beginning of period	26,552	46,216	49,825
Cash and cash equivalents at end of period	18,288	26,552	46,216
Cash paid (refunded) during the year for:
Interest	24,924	13,176	12,207
Income taxes	$ 2,720	$ 5,719	$ (2,741)