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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
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Defined Benefit Plan Assumed Health Care Cost Trend Rates [Abstract]
Pre-65			7.50%
Post-65	8.00%	8.40%	8.40%

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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

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- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	sptn_
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- References

No definition available.

+ Details

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