Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2015	Jun. 27, 2014	Jun. 26, 2015	Jun. 27, 2014
Income Statement [Abstract]
Net sales	$ 414,162	$ 491,517	$ 849,647	$ 952,609
Cost of sales	126,590	162,391	282,853	314,259
Gross margin	287,572	329,126	566,794	638,350
Research and development expense	105,345	101,121	208,576	198,778
Selling, general, and administrative expense	75,011	78,974	145,517	153,481
Amortization of acquisition-related intangible assets	2,427	2,464	4,891	4,929
Merger expenses	18,458	0	18,458	0
Compensation expense — deferred compensation plan	2,732	3,126	2,759	4,580
Gain on deferred compensation plan securities	(2,732)	(3,126)	(2,759)	(4,580)
Interest income and other	(8,495)	(7,819)	(15,091)	(13,804)
Gain reclassified from other comprehensive income	(1,463)	(43)	(3,969)	(91)
Interest expense	10,859	10,877	21,267	21,365
Income before income taxes	85,430	143,552	187,145	273,692
Income tax expense	15,091	16,548	21,954	30,174
Net income	70,339	127,004	165,191	243,518
Unrealized holding gain on investments:
Unrealized holding (loss)/gain on investments arising during period, net of tax of ($460), $23, ($419) and $46	(24,805)	14,471	(8,020)	27,031
Less: Reclassification adjustments for gain on investments included in net income, net of tax of $9, $6, $15 and $10	(1,454)	(37)	(3,954)	(81)
Other comprehensive (loss)/income	(26,259)	14,434	(11,974)	26,950
Comprehensive income	$ 44,080	$ 141,438	$ 153,217	$ 270,468
Net income per share (in dollars per share):
Basic (in dollars per share)	$ 0.23	$ 0.41	$ 0.55	$ 0.78
Diluted (in dollars per share)	$ 0.23	$ 0.41	$ 0.54	$ 0.77
Shares used in computing per share amounts (in shares):
Basic (in shares)	301,799	311,000	301,561	313,713
Diluted (in shares)	304,604	313,513	303,951	316,145
Dividends per common share	$ 0.18	$ 0.15	$ 0.36	$ 0.30