Marketable Securities (Details)	12 Months Ended
Sep. 28, 2018
Investments, Debt and Equity Securities [Abstract]
available for sale securities, debt maturities	two years or less

Date of maturity of a debt security categorized as neither trading nor held to maturity, string text

No definition available.

Name:	swks_Availableforsalesecuritiesdebtmaturities
Namespace Prefix:	swks_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration