Balance sheet components - Narrative (Details) $ in Millions	Jun. 30, 2018 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Deferred revenue expected to be recognized, remainder of fiscal 2018	$ 8.9
Deferred revenue expected to be recognized, fiscal 2019	11.0
Deferred revenue expected to be recognized, fiscal 2020	10.3
Deferred revenue expected to be recognized, fiscal 2021	9.0
Deferred revenue expected to be recognized, fiscal 2022	7.2
Deferred revenue expected to be recognized, thereafter	$ 9.4

Contract with Customer, Liability, Deferred Revenue Expected to be Recognized, After Year Five

No definition available.

Name:	sono_ContractwithCustomerLiabilityDeferredRevenueExpectedtobeRecognizedAfterYearFive
Namespace Prefix:	sono_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Contract with Customer, Liability, Deferred Revenue Expected to be Recognized, Remainder of Fiscal Year

No definition available.

Name:	sono_ContractwithCustomerLiabilityDeferredRevenueExpectedtobeRecognizedRemainderofFiscalYear
Namespace Prefix:	sono_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Contract with Customer, Liability, Deferred Revenue Expected to be Recognized, Year Five

No definition available.

Name:	sono_ContractwithCustomerLiabilityDeferredRevenueExpectedtobeRecognizedYearFive
Namespace Prefix:	sono_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Contract with Customer, Liability, Deferred Revenue Expected to be Recognized, Year Four

No definition available.

Name:	sono_ContractwithCustomerLiabilityDeferredRevenueExpectedtobeRecognizedYearFour
Namespace Prefix:	sono_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Contract with Customer, Liability, Deferred Revenue Expected to be Recognized, Year Three

No definition available.

Name:	sono_ContractwithCustomerLiabilityDeferredRevenueExpectedtobeRecognizedYearThree
Namespace Prefix:	sono_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Contract with Customer, Liability, Deferred Revenue Expected to be Recognized, Year Two

No definition available.

Name:	sono_ContractwithCustomerLiabilityDeferredRevenueExpectedtobeRecognizedYearTwo
Namespace Prefix:	sono_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

No definition available.

Name:	us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration