Marketable Securities Contractual Maturity (Details)	6 Months Ended
Mar. 29, 2019
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Securities, Debt Maturities, Date	2 years

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

No definition available.

Name:	swks_DebtSecuritiesAvailableforsaleNoncurrentMaximumContractualMaturity
Namespace Prefix:	swks_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration