Business Segments - EBITDA and Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting [Abstract]
Adjusted EBITDA													$ 49,045	$ 27,315	$ 57,494
Depreciation and amortization													(12,328)	(12,988)	(13,390)
Stock-based compensation - equity classified awards													(5,533)	(5,302)	(6,820)
Stock-based compensation - SARs market-to-market													(748)	0	0
Restructuring charges		$ (2,892)									$ (10,524)		(15,918)	(6,031)	0
Executive search fees													(80)	(235)	(454)
Professional fees related to control remediation													(1,130)	(2,430)	0
Sales and use tax audit													(25)	(113)	(203)
Other professional fees													(2,241)	(507)	0
Goodwill impairment					$ (18,400)	$ (27,900)							0	(46,319)	0
Intangible and long-lived asset impairment						(13,800)							0	(18,121)	0
Senior leadership transition and other employee-related costs													0	(1,410)	0
Obsolete retail inventory													0	(950)	0
Professional fees related to ASC 606 implementation													0	(1,092)	(829)
Business development realignment													0	0	(715)
Change in fair value of contingent consideration													0	0	(677)
Czech currency impact on procurement margin													0	0	(860)
Income (loss) from operations	$ 3,588	3,762	$ 4,063	$ (371)	(28,232)	(43,312)	$ 2,377	$ 984	$ 3,692	$ 3,361	7,454	$ (39,951)	11,042	(68,183)	33,546
Interest income													366	218	97
Interest expense													(14,097)	(7,749)	(4,729)
Other, net		(1,735)	279	(440)					(161)		(1,896)		(3,686)	(1,616)	(1,788)
(Loss) income before income taxes		(2,312)	1,960	(3,458)	(30,926)	(45,363)	326	(1,368)	(1,499)	(1,042)	(3,811)	(46,404)	(6,375)	(77,330)	27,126
(Benefit) provision for income tax		1,250	(2,468)	1,414	1,536	243	(625)	(506)	(1,053)	(1,131)	197	(889)	(3,700)	647	(11,257)
Net (loss) income	$ (6,461)	$ (1,062)	$ (508)	$ (2,044)	$ (29,390)	$ (45,120)	$ (299)	$ (1,874)	$ (2,552)	$ (2,173)	$ (3,614)	$ (47,293)	$ (10,075)	$ (76,683)	$ 15,869