Defined benefit plan, expected assets distribution period.

No definition available.

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Balance Type:	na
Period Type:	duration

- Definition

Defined benefit plan pre-tax settlement charge.

+ References

No definition available.

+ Details

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

- Definition

Defined benefit plan, termination date.

+ References

No definition available.

+ Details

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Namespace Prefix:	sptn_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of contribution received by defined benefit plan from employer which increases plan assets.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of contributions expected to be received by defined benefit plan from employer in fiscal year. Excludes contributions paid by employer in current fiscal year.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 6
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-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2709-114920

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of net periodic benefit cost (credit) for defined benefit plan.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of contributions made to multiemployer plan by all employers who participate in plan.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
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-Paragraph 7
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Balance Type:	credit
Period Type:	duration

- Details

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- Details

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- Details

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Balance Type:
Period Type:

- Details

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Balance Type:
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- Details

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Associate Retirement Plans - Additional Information (Detail) - USD ($)		3 Months Ended		6 Months Ended
	Feb. 28, 2018	Jul. 14, 2018	Jul. 15, 2017	Jul. 14, 2018	Jul. 15, 2017
Defined Benefit Plan Disclosure [Line Items]
Pension contributions during last plan year		$ 3,400,000	$ 3,400,000	$ 7,900,000	$ 7,800,000
Pension Plan or Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
One-time, pre-tax settlement charge	$ 22,000,000
Frozen pension plan, termination date				Jul. 31, 2018
Pension Plan or Plan [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Distribution of assets to plan participants, expected period				9 months
Pension Plan or Plan [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Distribution of assets to plan participants, expected period				21 months
Retiree Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected Company contribution for remainder of fiscal year		400,000		$ 400,000
SpartanNash Company Pension Plan [Member] \| Pension Plan or Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income) expense		(100,000)	(200,000)	(200,000)	(300,000)
Standard pension funding carryover				0
SpartanNash Company Pension Plan [Member] \| Pension Plan or Plan [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected Company contribution for remainder of fiscal year		2,000,000		2,000,000
SpartanNash Company Pension Plan [Member] \| Pension Plan or Plan [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected Company contribution for remainder of fiscal year		3,000,000		3,000,000
SpartanNash Retiree Medical Plan [Member] \| Retiree Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income) expense		$ 100,000	$ 100,000	$ 200,000	$ 200,000