Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017
Statement of Cash Flows [Abstract]
Cash and cash equivalents at beginning of period	$ 688,087	$ 465,232
Cash flows from operating activities:
Net income	247,352	218,543
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	89,003	86,605
Amortization of debt discount and fees	950	920
Stock-based compensation	125,121	94,008
Gain on investments, net	(2,617)	(12,502)
Deferred income taxes	(3,221)	212
Provisions for losses on receivables	4,790	1,499
Other non-cash items	1,589	3,763
Changes in operating assets and liabilities, net of effect of acquired businesses:
Receivables	(28,471)	(9,539)
Inventories	(1,455)	2,282
Prepaid expenses and other	2,018	(4,627)
Other assets	3,571	(14,469)
Accounts payable and accrued liabilities	(41,718)	(41,127)
Deferred revenue	77,370	14,245
Other long-term liabilities	(1,415)	4,071
Net cash provided by operating activities	472,867	343,884
Cash flows from investing activities:
Proceeds from the sale of available-for-sale securities	0	421
Proceeds from the sale of long-term investments	0	9,108
Purchases of property, plant and equipment	(41,761)	(39,676)
Cash paid in business combinations and asset acquisitions, net of cash acquired	0	(550)
Net cash used for investing activities	(41,761)	(30,697)
Cash flows from financing activities:
Proceeds from revolving credit facility	0	50,000
Payment on revolving credit facility	(85,000)	(100,000)
Principal payments on term loan	(300,000)	0
Payment of debt issuance costs	0	(793)
Proceeds from issuance of common stock	38,190	45,419
Stock received for payment of employee taxes on vesting of restricted stock	(59,619)	(54,130)
Payments for repurchases of common stock	(150,036)	(50,013)
Change in book overdraft	(3,867)	0
Net cash used for financing activities	(560,332)	(109,517)
Effect of exchange rate changes on cash and cash equivalents	(14,276)	9,382
Increase (decrease) in cash and cash equivalents	(143,502)	213,052
Cash and cash equivalents at end of period	544,585	678,284
Supplemental cash flow information:
Cash paid for interest	15,360	14,188
Cash paid for taxes, net	$ 29,858	$ 40,021