CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue	[1]	$ 378,831	$ 402,874	$ 403,558
Total cost of revenue		183,834	179,862	194,349
Total gross profit		194,997	223,012	209,209
Operating expenses:
Research and development		82,494	84,614	89,163
Selling, general and administrative		119,611	119,035	118,952
Amortization of intangibles		3,019	3,139	3,187
Restructuring and related charges		2,322	3,141	2,918
Total operating expenses		207,446	209,929	214,220
Income (loss) from operations		(12,449)	13,083	(5,011)
Interest expense, net		(11,509)	(11,651)	(11,401)
Loss on convertible debt extinguishment		(1,362)	(5,695)	0
Other expense, net		(897)	(2,333)	(536)
Loss before income taxes		(26,217)	(6,596)	(16,948)
Provision for (benefit from) income taxes		3,054	(672)	4,087
Net loss		$ (29,271)	$ (5,924)	$ (21,035)
Net loss per share:
Basic and diluted		$ (0.30)	$ (0.07)	$ (0.25)
Shares used in per share calculations:
Basic and diluted		96,971	89,575	85,615
Appliance & Integration [Member]
Revenue		$ 252,014	$ 275,797	$ 287,564
Total cost of revenue		126,948	130,284	148,472
SaaS and service
Revenue		126,817	127,077	115,994
Total cost of revenue		$ 56,886	$ 49,578	$ 45,877

[1] Revenue is attributed to countries based on the location of the customer.