Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Jun. 30, 2018	Dec. 30, 2017
Income Taxes [Abstract]
2017 TCJA Provisional Tax Benefit		$ 1.7
Tax Cuts And Jobs Act Of 2017 Measurement Period Adjustment Income Tax Expense Benefit	$ 2.9

Amount of income tax expense (benefit) for measurement period adjustment from accounting for tax effect pursuant to Tax Cuts and Jobs Act.

No definition available.

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Namespace Prefix:	snbr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration