Line of credit facility additional borrowing capacity.

No definition available.

Name:	sptn_LineOfCreditFacilityAdditionalBorrowingCapacity
Namespace Prefix:	sptn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of credit facility percentage of maintenance of excess borrowing base.

+ References

No definition available.

+ Details

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

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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

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

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of long-term debt outstanding calculated at point in time.

+ References

No definition available.

+ Details

Name:	us-gaap_LongtermDebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentAxis=sptn_CreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=sptn_TrancheAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=sptn_TrancheAOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=sptn_TrancheATwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Long-Term Debt - Additional Information (Detail) - USD ($)		12 Months Ended
	Dec. 18, 2018	Dec. 28, 2019	Dec. 29, 2018	Dec. 31, 2016
Debt Instrument [Line Items]
Unused portion of loan commitments rate		0.25%
Maintenance of excess borrowing base		10.00%
Current borrowing available under credit facility		$ 236,800,000	$ 262,000,000.0
Weighted average interest rate of convertible senior notes		4.56%
Credit Agreement [Member]
Debt Instrument [Line Items]
Additional borrowings available under credit facility	$ 325,000,000
Tranche A [Member] \| Minimum [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
LIBOR plus interest rate		1.25%
Tranche A [Member] \| Maximum [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
LIBOR plus interest rate		1.50%
Tranche A-1 [Member] \| Minimum [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
LIBOR plus interest rate		2.25%
Tranche A-1 [Member] \| Maximum [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
LIBOR plus interest rate		2.50%
Revolving credit agreement [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Notes maturity date	Dec. 20, 2021
Revolving credit agreement [Member] \| Credit Agreement [Member] \| Extended Maturity [Member]
Debt Instrument [Line Items]
Notes maturity date	Dec. 18, 2023
Revolving credit agreement [Member] \| Tranche A [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Available borrowings under credit facility	$ 975,000,000			$ 900,000,000
Revolving credit agreement [Member] \| Tranche A-1 [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Available borrowings under credit facility				$ 40,000,000
Revolving credit agreement [Member] \| Tranche A-1 [Member] \| Credit Agreement [Member] \| Minimum [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
LIBOR plus interest rate	2.25%
Revolving credit agreement [Member] \| Tranche A-1 [Member] \| Credit Agreement [Member] \| Maximum [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
LIBOR plus interest rate	2.50%
Revolving credit agreement [Member] \| Tranche A-2 [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Available borrowings under credit facility	$ 60,000,000
Letter of credit [Member]
Debt Instrument [Line Items]
Unused borrowing capacity		$ 11,700,000	$ 11,700,000