Intangible Assets (Details) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Apr. 01, 2017	Jul. 01, 2017	Dec. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Impairment of intangible assets	$ 0	$ 0
Accumulated amortization, intangible assets	106,100,000			$ 100,300,000
Amortization of acquired intangible assets	5,763,000	8,687,000
Research and development
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangible assets	127,000	173,000
Amortization of acquired intangible assets
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangible assets	$ 5,636,000	8,514,000
Patents
Finite-Lived Intangible Assets [Line Items]
Proceeds from sale of intangible assets		$ 18,000,000
Decrease of intangible assets, net of amortization			$ 3,500,000