Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Apr. 01, 2017	Mar. 31, 2018	Apr. 01, 2017
Income Statement [Abstract]
Net sales	$ 481,118	$ 422,833	$ 958,683	$ 768,906
Cost of sales	265,688	243,318	526,230	447,877
Gross profit	215,430	179,515	432,453	321,029
Operating expenses:
Research and development	34,783	30,536	66,175	57,620
Selling, general and administrative	77,146	72,451	150,583	146,219
Gain from business combination	0	0	0	(5,416)
Other impairment charges (recoveries)	(110)	0	155	0
Amortization of intangible assets	2,950	5,439	5,556	9,317
Total operating expenses	114,769	108,426	222,469	207,740
Income from operations	100,661	71,089	209,984	113,289
Other income (expense):
Interest income	440	135	911	278
Interest expense	(7,725)	(8,998)	(16,472)	(16,962)
Other—net	(2,225)	(1,392)	(2,449)	11,601
Total other income (expense), net	(9,510)	(10,255)	(18,010)	(5,083)
Income from continuing operations before income taxes	91,151	60,834	191,974	108,206
Provision for income taxes	25,849	18,646	84,769	35,320
Net income from continuing operations	65,302	42,188	107,205	72,886
Loss from discontinued operations, net of income taxes	0	(343)	(2)	(633)
Net income	$ 65,302	$ 41,845	$ 107,203	$ 72,253
Basic net income per share:
Income per share from continuing operations (in USD per share)	$ 2.64	$ 1.72	$ 4.34	$ 2.98
Loss per share from discontinued operations, net of income taxes (in USD per share)	0.00	(0.01)	0.00	(0.03)
Net income per share (in USD per share)	2.64	1.71	4.34	2.96
Diluted net income per share:
Income per share from continuing operations (in USD per share)	2.61	1.70	4.29	2.95
Loss per share from discontinued operations, net of income taxes (in USD per share)	0.00	(0.01)	0.00	(0.03)
Net income per share (in USD per share)	$ 2.61	$ 1.69	$ 4.29	$ 2.93
Shares used in computation:
Basic (shares)	24,761	24,496	24,698	24,422
Diluted (shares)	25,010	24,757	25,018	24,700