Debt instrument elimination expansion.

No definition available.

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Period Type:	duration

- Definition

Debt instrumnet estimated periodic minimum liquidity

+ References

No definition available.

+ Details

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- Definition

Line of credit facility amount borrowed.

+ References

No definition available.

+ Details

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

- Definition

Line of credit facility maturity date

+ References

No definition available.

+ Details

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- Definition

Line of credit facility upfront fee payable.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Minimum building adjusted EBITDA.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Minimum liquidity level.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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

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

- Definition

Incremental percentage increase (decrease) in the stated rate on a debt instrument.

+ References

No definition available.

+ Details

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- 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
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- 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=120391452&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

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

- Definition

Average amount borrowed under the credit facility during the period.

+ References

No definition available.

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

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

- 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=120391452&loc=d3e13212-122682

+ Details

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

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

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

- Definition

Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase (decrease) of the credit facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

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

- 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

+ Details

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

- Definition

Amount of cash outflow for payment of an obligation from a lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Carrying value as of the balance sheet date of uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

+ 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)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Details

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Period Type:

- Details

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Debt and Credit Facilities - Additional Information (Detail) - USD ($)					1 Months Ended		12 Months Ended
	Feb. 26, 2021	Nov. 04, 2020	Aug. 10, 2020	Aug. 07, 2019	Jul. 17, 2020	May 15, 2020	Dec. 27, 2020	Dec. 29, 2019	Mar. 17, 2020
Debt Instrument [Line Items]
Line of credit facility amount borrowed							$ 55,000,000
Line of credit facility amount borrowed					$ 10,000,000.0
February 28, 2022 [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Minimum Liquidity Level							15,000,000.0
Minimum Building Adjusted EBITDA							(18,000,000.0)
February 28, 2022 [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Minimum Liquidity Level							30,000,000.0
Minimum Building Adjusted EBITDA							8,300,000
Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Upfront fee payable						1.00%
CARES Act Of 2020 [Member]
Debt Instrument [Line Items]
Line of credit facility amount borrowed							33,500,000
CARES Act Of 2020 [Member] \| Minimum [Member] \| Fourth Credit Agreement Amendment
Debt Instrument [Line Items]
Debt instrumnet estimated periodic Minimum Liquidity		$ 23,000.0						$ 25,000.0
CARES Act Of 2020 [Member] \| Minimum [Member] \| Fifth Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Debt Instrument, maturity date	Mar. 31, 2022
CARES Act Of 2020 [Member] \| Maximum [Member] \| Fourth Credit Agreement Amendment
Debt Instrument [Line Items]
Debt instrumnet estimated periodic Minimum Liquidity		$ 37,500						37,500
CARES Act Of 2020 [Member] \| Maximum [Member] \| Fifth Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Debt Instrument, maturity date	Jan. 31, 2023
London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Credit facility agreement, interest rate				1.75%	4.75%
London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member] \| Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Credit facility agreement, interest rate						5.00%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Credit facility agreement, interest rate				1.25%	1.00%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member] \| Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Credit facility agreement, interest rate						1.00%
Prime Rate [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Credit facility agreement, interest rate					2.25%
JPMorgan Chase Bank, N.A. [Member]
Debt Instrument [Line Items]
Commitment fee, percentage				0.20%
JPMorgan Chase Bank, N.A. [Member] \| Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Commitment fee, percentage						1.00%
Debt instrument, elimination expansion						$ 20,000,000.0
Credit facility agreement, amount outstanding						15,000,000.0
Line of credit facility amount borrowed						$ 28,000,000.0
JPMorgan Chase Bank, N.A. [Member] \| Maximum [Member] \| Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Credit facility agreement, Maturity date						Mar. 31, 2022
JPMorgan Chase Bank, N.A. [Member] \| Minimum [Member] \| Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Credit facility agreement, Maturity date						Jul. 31, 2022
JPMorgan Chase Bank, N.A. [Member] \| Prime Rate [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Credit facility agreement, interest rate				0.50%
JPMorgan Chase Bank, N.A. [Member] \| Prime Rate [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Credit facility agreement, interest rate				0.00%
JPMorgan Chase Bank, N.A. [Member] \| Prime Rate [Member] \| Minimum [Member] \| Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Credit facility agreement, interest rate						4.00%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility agreement, maximum principal amount					$ 40,000,000.0
Credit facility agreement, future increases					30,000,000.0
Line of credit facility amount borrowed					$ 14,500,000
Revolving Credit Facility [Member] \| CARES Act Of 2020 [Member]
Debt Instrument [Line Items]
Line of credit facility amount borrowed									$ 39,800,000
Revolving Credit Facility [Member] \| JPMorgan Chase Bank, N.A. [Member]
Debt Instrument [Line Items]
Credit facility agreement, expiration date				Jul. 31, 2022
Credit facility agreement, maximum principal amount				$ 40,000,000
Revolving Credit Facility [Member] \| JPMorgan Chase Bank, N.A. [Member] \| Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Line of credit facility amount borrowed						$ 15,000,000.0
Revolving Credit Facility [Member] \| JPMorgan Chase Bank, N.A. [Member] \| COVID 19 [Member]
Debt Instrument [Line Items]
Line of credit facility amount borrowed									$ 39,800,000
Revolving Credit Facility [Member] \| JPMorgan Chase Bank, N.A. [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Credit facility agreement, future increases				$ 20,000,000
Paycheck Protection Program Loan [Member] \| Harvest Small Business Finance [Member] \| Commercial Loan [Member] \| Potbelly Sandwich Works, LLC [Member]
Debt Instrument [Line Items]
Loan amount			$ 10,000,000.0
Paycheck Protection Program Loan [Member] \| CARES Act Of 2020 [Member] \| Potbelly Sandwich Works, LLC [Member]
Debt Instrument [Line Items]
Credit facility agreement, interest rate			1.00%
Loan maturity period			5 years
Paycheck Protection Program Loan [Member] \| CARES Act Of 2020 [Member] \| Harvest Small Business Finance [Member] \| Third Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Line of credit facility amount borrowed							10,000,000.0
Credit facility agreement, amount outstanding							$ 6,300,000	$ 0
Revolving Credit Commitment [Member] \| CARES Act Of 2020 [Member] \| Minimum [Member] \| Fifth Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Credit facility agreement, future increases	$ 40,000,000
Revolving Credit Commitment [Member] \| CARES Act Of 2020 [Member] \| Maximum [Member] \| Fifth Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Credit facility agreement, future increases	$ 25,000,000
CBFR Loan [Member] \| CARES Act Of 2020 [Member] \| Fifth Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Debt instrument, increase in interest rate	50.00%
Eurodollar Loan [Member] \| CARES Act Of 2020 [Member] \| Fifth Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Debt instrument, increase in interest rate	25.00%