CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)		3 Months Ended
		Mar. 28, 2020	Mar. 30, 2019
Cash Flows from Operating Activities:
Net loss		$ (99,268,000)	$ (121,601,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization		25,445,000	30,939,000
Non-cash restructuring charges and related costs		1,760,000	16,851,000
Amortization of debt discount and issuance costs		5,731,000	4,614,000
Operating lease expense		5,204,000	14,966,000
Stock-based compensation expense		11,703,000	8,713,000
Other, net		1,153,000	1,775,000
Changes in assets and liabilities:
Accounts receivable		70,238,000	49,754,000
Inventory		17,737,000	(24,937,000)
Prepaid expenses and other assets		(18,744,000)	(5,236,000)
Accounts payable		(72,355,000)	(23,439,000)
Accrued liabilities and other expenses		(32,083,000)	(15,486,000)
Deferred revenue		(8,038,000)	6,933,000
Net cash used in operating activities		(91,517,000)	(56,154,000)
Cash Flows from Investing Activities:
Proceeds from maturities of investments		0	10,542,000
Acquisition of business, net of cash acquired		0	(10,000,000)
Purchase of property and equipment, net		(8,464,000)	(6,590,000)
Net cash used in investing activities		(8,464,000)	(6,048,000)
Cash Flows from Financing Activities:
Proceeds from issuance of 2027 Notes		194,500,000	0
Proceeds from mortgage payable		0	8,584,000
Proceeds from revolving line of credit		55,000,000	0
Repayment of revolving line of credit		0	0
Payment of debt issuance cost		(1,775,000)
Repayment of mortgage payable		(99,000)	0
Proceeds from issuance of common stock		7,395,000	7,740,000
Net cash provided by financing activities		255,021,000	16,324,000
Effect of exchange rate changes on cash and restricted cash		(4,369,000)	(1,213,000)
Net change in cash, cash equivalents and restricted cash		150,671,000	(47,091,000)
Cash, cash equivalents and restricted cash at beginning of period		132,797,000	242,337,000
Cash, cash equivalents and restricted cash at end of period	[1]	283,468,000	195,246,000
Supplemental disclosures of cash flow information:
Cash paid for income taxes, net of refunds		1,072,000	1,353,000
Cash paid for interest		5,131,000	4,315,000
Supplemental schedule of non-cash investing and financing activities:
Unpaid debt issuance cost		1,793,000	0
Transfer of inventory to fixed assets		118,000	1,805,000
Restricted Cash and Cash Equivalents [Abstract]
Total cash, cash equivalents and restricted cash	[1]	$ 283,468,000	$ 195,246,000

[1] Reconciliation of cash, cash equivalents and restricted cash to the condensed consolidated balance sheets:   March 28,
2020   March 30,
2019           (In thousands) Cash and cash equivalents $ 261,534
  $ 167,259
Short-term restricted cash 4,126
  4,671
Long-term restricted cash 17,808
  23,316
Total cash, cash equivalents and restricted cash $ 283,468
  $ 195,246