Recent Accounting Pronouncements - Revenue From Contracts With Customers, Financial Statement Impact (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 29, 2018	Jun. 30, 2017	Jun. 29, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenue	$ 99,160	$ 82,315	$ 189,287	$ 165,258
Total cost of revenue	47,557	48,500	90,501	91,035
Gross Profit	51,603	33,815	98,786	74,223
Selling, general and administrative	27,988	32,625	59,151	67,256
Loss from operations	642	(27,422)	(8,685)	(48,580)
Loss before income taxes	(2,022)	(30,921)	(14,638)	(55,180)
Net loss	(2,913)	$ (31,500)	(16,607)	$ (55,527)
Accounts receivable, net	82,635		82,635			$ 69,844
Prepaid expenses and other current assets	19,377		19,377			18,931
Other long-term assets	42,863		42,863			42,913
Deferred revenue	56,278		56,278			52,429
Other non-current liabilities	19,169		19,169			22,626
Accumulated deficit	(2,062,988)		(2,062,988)			$ (2,057,812)
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable, net					$ 71,625
Prepaid expenses and other current assets					22,509
Other long-term assets					43,686
Deferred revenue					47,603
Other non-current liabilities					22,153
Accumulated deficit					(2,046,381)
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenue	98,714		188,037
Total cost of revenue	47,316		90,141
Gross Profit	51,398		97,896
Selling, general and administrative	28,570		59,541
Loss from operations	(145)		(9,965)
Loss before income taxes	(2,809)		(15,918)
Net loss	(3,700)		(17,887)
Accounts receivable, net	78,065		78,065
Prepaid expenses and other current assets	15,918		15,918
Other long-term assets	42,360		42,360
Deferred revenue	60,032		60,032
Other non-current liabilities	19,594		19,594
Accumulated deficit	(2,075,699)		(2,075,699)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenue	446		1,250
Total cost of revenue	241		360
Gross Profit	205		890
Selling, general and administrative	(582)		(390)
Loss from operations	787		1,280
Loss before income taxes	787		1,280
Net loss	787		1,280
Accounts receivable, net	4,570		4,570		1,781
Prepaid expenses and other current assets	3,459		3,459		3,578
Other long-term assets	503		503		773
Deferred revenue	(3,754)		(3,754)		(4,826)
Other non-current liabilities	(425)		(425)		(473)
Accumulated deficit	$ 12,711		$ 12,711		$ 11,431