CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net revenues:
Products	$ 209,461	$ 283,110	$ 336,371
Services	209,542	228,820	169,224
Total net revenues	419,003	511,930	505,595
Cost of revenues:
Products	112,606	111,579	131,881
Services	56,481	59,828	61,501
Amortization of intangible assets	7,800	7,800	4,063
Total cost of revenues	176,887	179,207	197,445
Gross profit	242,116	332,723	308,150
Operating expenses:
Research and development	68,212	81,564	95,898
Marketing and selling	106,257	110,338	122,511
General and administrative	53,892	61,471	74,109
Amortization of intangible assets	1,450	2,498	2,354
Restructuring costs, net	7,059	12,837	6,305
Total operating expenses	236,870	268,708	301,177
Operating income	5,246	64,015	6,973
Interest income	535	0	113
Interest expense	(19,964)	(18,903)	(6,346)
Other income (expense), net	761	232	(175)
(Loss) income before income taxes	(13,422)	45,344	565
Provision for (benefit from) income taxes	133	(2,875)	(1,915)
Net (loss) income	$ (13,555)	$ 48,219	$ 2,480
Net (loss) income per common share - basic	$ (0.33)	$ 1.20	$ 0.06
Weighted-average common shares outstanding - basic	41,020	40,021	39,423
Weighted-average common shares outstanding - diluted	41,020	40,176	40,380