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Concentration of Credit Risk - Additional Information (Detail) $ in Millions | 12 Months Ended
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Dec. 29, 2018 USD ($) Retailer
Concentration Of Credit Risk [Line Items] |
Number of independent retailer for unearned advanced amount | Retailer | 1
Percent of unearned advanced amount to total assets | 2.00%
Amount of charge resulted in analysis of net realizability of the underlying collateral | $ 32.0
Present value of potential obligation for sub-lease | 5.9
Assigned sublease obligation | $ 14.1
Minimum [Member] |
Concentration Of Credit Risk [Line Items] |
Loan repayable period | 5 years
Maximum [Member] |
Concentration Of Credit Risk [Line Items] |
Loan repayable period | 10 years

X
- Definition Assigned sublease obligation. + References No definition available. + Details
Name: | sptn_AssignedSubleaseObligation
Namespace Prefix: | sptn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Collateral related charges. + References No definition available. + Details
Name: | sptn_CollateralRelatedCharges
Namespace Prefix: | sptn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Concentration of credit risk. + References No definition available. + Details
Name: | sptn_ConcentrationOfCreditRiskLineItems
Namespace Prefix: | sptn_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Loan repayable period. + References No definition available. + Details
Name: | sptn_LoanRepayablePeriod
Namespace Prefix: | sptn_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of independent retailer unearned advanced amount. + References No definition available. + Details
Name: | sptn_NumberOfIndependentRetailerUnearnedAdvancedAmount
Namespace Prefix: | sptn_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percent of unearned advanced amount to net assets. + References No definition available. + Details
Name: | sptn_PercentOfUnearnedAdvancedAmountToNetAssets
Namespace Prefix: | sptn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Present value of maximum potential sublease obligation. + References No definition available. + Details
Name: | sptn_PresentValueOfMaximumPotentialSubleaseObligation
Namespace Prefix: | sptn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |