CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 28, 2015	Jun. 29, 2014	Jun. 28, 2015	Jun. 29, 2014
Income Statement [Abstract]
Net sales	$ 317,066	$ 292,301	$ 916,828	$ 834,948
Cost of sales	144,976	138,711	407,398	394,411
Gross profit	172,090	153,590	509,430	440,537
Operating expenses:
Selling, general and administrative	66,671	61,141	187,764	181,513
Research and development costs	52,340	48,044	146,298	141,452
Amortization of intangible assets	24,811	23,422	71,084	69,694
Restructuring and severance charges	3,098	14,653	14,011	27,073
Total operating expenses	146,920	147,260	419,157	419,732
Operating income	25,170	6,330	90,273	20,805
Other expenses
Interest expense, net	(7,408)	(6,459)	(19,489)	(21,656)
Other expense, net	(566)	(627)	(1,409)	(2,132)
Total other expense	(7,974)	(7,086)	(20,898)	(23,788)
Income (loss) before income taxes	17,196	(756)	69,375	(2,983)
Provision for income taxes	2,533	3,537	10,138	6,690
Net income (loss)	$ 14,663	$ (4,293)	$ 59,237	$ (9,673)
Earnings (loss) per share:
Basic (USD per share)	$ 0.16	$ (0.05)	$ 0.63	$ (0.10)
Diluted (USD per share)	$ 0.15	$ (0.05)	$ 0.62	$ (0.10)
Weighted-average common shares outstanding:
Basic	94,462	93,095	94,122	92,664
Diluted	96,371	93,095	95,614	92,664
Net income (loss)	$ 14,663	$ (4,293)	$ 59,237	$ (9,673)
Other comprehensive income (loss), net of tax:
Translation adjustment	(3,576)	(346)	(1,433)	100
Unrealized actuarial loss on pension benefits	(69)	(44)	(213)	(132)
Other comprehensive loss, net of tax	(3,645)	(390)	(1,646)	(32)
Total comprehensive income (loss)	$ 11,018	$ (4,683)	$ 57,591	$ (9,705)