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Business and Summary of Significant Accounting Policies - New Accounting Pronouncements - Additional Information (Details) $ in Millions | 12 Months Ended
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Jan. 02, 2021 USD ($)
Accounting Policies [Abstract] |
Amount of lease payments deferred due to COVID-19 | $ 3.1

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- Definition Lease Payment Deferral, COVID-19 + References No definition available. + Details
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Namespace Prefix: | snbr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_AccountingPoliciesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration