Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Statement of Cash Flows [Abstract]
Cash and cash equivalents at beginning of period	$ 465,232	$ 616,686
Cash flows from operating activities:
Net income	68,259	50,562
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	28,894	31,231
Amortization of debt discount and fees	350	255
Stock-based compensation	27,436	24,632
Gain on investments, net	(1,228)	(2,617)
Deferred income taxes	1,990	1,623
Other non-cash items	1,359	209
Changes in operating assets and liabilities, net of effect of acquired businesses:
Receivables	(22,475)	11,618
Inventories	6,000	(3,714)
Prepaid expenses and other	(3,777)	(10,132)
Other assets	(3,657)	(3,595)
Accounts payable and accrued liabilities	(46,159)	(42,557)
Deferred revenue	34,325	30,710
Other long-term liabilities	1,113	(5,034)
Net cash provided by operating activities	92,430	83,191
Cash flows from investing activities:
Purchases of available-for-sale securities	0	(20,525)
Proceeds from the sale of available-for-sale securities	107	1,000
Proceeds from the maturity of available-for-sale securities	0	19,000
Proceeds from the sale of long-term investments	0	2,583
Purchases of property, plant and equipment	(14,843)	(12,116)
Cash paid in business combinations and asset acquisitions, net of cash acquired	0	(3,853)
Net cash used for investing activities	(14,736)	(13,911)
Cash flows from financing activities:
Proceeds from term loan	0	300,000
Proceeds from revolving credit facility	50,000	50,000
Payment on revolving credit facility	(50,000)	0
Payment of debt issuance costs	(793)	(542)
Proceeds from issuance of common stock	22,715	24,200
Stock received for payment of employee taxes on vesting of restricted stock	(22,470)	(15,225)
Payments for repurchases of common stock	0	(240,000)
Net cash provided by (used for) financing activities	(548)	118,433
Effect of exchange rate changes on cash and cash equivalents	1,750	6,001
Increase in cash and cash equivalents	78,896	193,714
Cash and cash equivalents at end of period	544,128	810,400
Supplemental cash flow information:
Cash paid for interest	2,219	109
Cash paid for taxes, net	$ 9,767	$ 4,799