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Associate Retirement Plans - Assumed Current Healthcare Cost Trend Rates Used to Determine Net Periodic Benefit Cost (Income) (Detail)	12 Months Ended
	Jan. 02, 2021	Dec. 28, 2019	Dec. 29, 2018
Defined Benefit Plan Assumed Health Care Cost Trend Rates [Abstract]
Post-65	7.50%	7.50%	8.00%

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- Definition

Defined benefit plan health care cost trend rate assumed for post sixty five year age.

+ References

No definition available.

+ Details

Name:	sptn_DefinedBenefitPlanHealthCareCostTrendRateAssumedForPostSixtyFiveYearAge
Namespace Prefix:	sptn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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- References

No definition available.

+ Details

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