CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net revenues:
Products	$ 205,107	$ 209,461	$ 283,110
Services	208,175	209,542	228,820
Total net revenues	413,282	419,003	511,930
Cost of revenues:
Products	110,758	112,606	111,579
Services	55,560	56,481	59,828
Amortization of intangible assets	7,800	7,800	7,800
Total cost of revenues	174,118	176,887	179,207
Gross profit	239,164	242,116	332,723
Operating expenses:
Research and development	62,379	68,212	81,564
Marketing and selling	101,273	106,257	110,338
General and administrative	55,230	53,892	61,471
Amortization of intangible assets	1,450	1,450	2,498
Restructuring costs, net	5,148	7,059	12,837
Total operating expenses	225,480	236,870	268,708
Operating income	13,684	5,246	64,015
Interest income	195	535	0
Interest expense	(23,474)	(19,964)	(18,903)
Other income (expense), net	192	761	232
(Loss) income before income taxes	(9,403)	(13,422)	45,344
Provision for (benefit from) income taxes	1,271	133	(2,875)
Net (loss) income	$ (10,674)	$ (13,555)	$ 48,219
Net (loss) income per common share - basic	$ (0.26)	$ (0.33)	$ 1.20
Weighted-average common shares outstanding - basic	41,662	41,020	40,021
Weighted-average common shares outstanding - diluted	41,662	41,020	40,176