Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Statement of Cash Flows [Abstract]
Cash and cash equivalents at beginning of period	$ 533,298	$ 688,087
Cash flows from operating activities:
Net income	120,555	72,885
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	29,740	29,389
Amortization of debt discount and fees	247	292
Stock-based compensation	42,253	37,901
Gain on investments, net	(2,646)	(996)
Deferred income taxes	(4,966)	1,363
Provisions for losses (recoveries) on receivables	(183)	666
Other non-cash items	122	(170)
Changes in operating assets and liabilities:
Receivables	35,681	(10,988)
Inventories	(10,618)	2,105
Prepaid expenses and other	15,618	8,392
Other assets	10,729	8,025
Accounts payable and accrued liabilities	(43,954)	(46,956)
Deferred revenue	(4,451)	59,854
Other long-term liabilities	(2,713)	(4,115)
Net cash provided by operating activities	185,414	157,647
Cash flows from investing activities:
Purchases of non-marketable investments	(33,664)	0
Proceeds from the sale of non-marketable investments	2,952	0
Purchases of property, plant and equipment	(15,275)	(13,128)
Net cash used for investing activities	(45,987)	(13,128)
Cash flows from financing activities:
Proceeds from revolving credit facility	50,000	0
Payment on revolving credit facility	(100,000)	(40,000)
Proceeds from issuance of common stock	29,858	23,339
Stock received for payment of employee taxes on vesting of restricted stock	(32,822)	(26,515)
Payments for repurchases of common stock	(81,114)	(50,013)
Change in book overdraft	0	(3,867)
Net cash used for financing activities	(134,078)	(97,056)
Effect of exchange rate changes on cash and cash equivalents	251	11,418
Increase in cash and cash equivalents	5,600	58,881
Cash and cash equivalents at end of period	538,898	746,968
Supplemental cash flow information:
Cash paid for interest	1,324	2,716
Cash paid for taxes, net	$ 6,892	$ 6,025