Consolidated Condensed Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 05, 2015	Mar. 30, 2014
Cash flows from operating activities:
Net income	$ 20,502	$ 18,506
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Stock-based compensation expense	6,946	4,004
Depreciation of property, plant, and equipment	2,346	1,990
Amortization of intangible assets	1,093	916
Amortization of discounts or premiums on investments	203	896
Realized gain on sale of investments	(29)	(501)
Tax effect of stock option exercises	(3,694)	(2,165)
Change in deferred income taxes	(1,251)	127
Increase (Decrease) in Other Operating Assets and Liabilities, Net	(26,380)	(6,312)
Net cash provided by (used in) operating activities	(264)	17,461
Cash flows from investing activities:
Purchases of investments	(157,083)	(124,734)
Maturities and sales of investments	130,476	117,753
Purchases of property, plant, and equipment	(4,264)	(2,685)
Net cash used in investing activities	(30,871)	(9,666)
Cash flows from financing activities:
Issuance of common stock under stock option plans	9,666	5,951
Repurchase of common stock	0	(14,287)
Tax effect of stock option exercises	3,694	2,165
Net cash provided by (used in) financing activities	13,360	(6,171)
Effect of foreign exchange rate changes on cash and cash equivalents	(1,872)	195
Net change in cash and cash equivalents	(19,647)	1,819
Cash and cash equivalents at beginning of period	55,694	40,644
Cash and cash equivalents at end of period	$ 36,047	$ 42,463