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Debt and Credit Facilities - Additional Information (Detail) - USD ($)				3 Months Ended
	Feb. 26, 2021	Aug. 10, 2020	Aug. 07, 2019	Mar. 28, 2021	Mar. 29, 2020
CARES Act Of 2020 [Member] | Fifth Credit Agreement Amendment [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, maturity date	Mar. 31, 2022
CARES Act Of 2020 [Member] | Fifth Credit Agreement Amendment [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, maturity date	Jan. 31, 2023
JPMorgan Chase Bank, N.A. [Member]
Debt Instrument [Line Items]
Commitment fee, percentage			0.20%
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] | Maximum [Member]
Debt Instrument [Line Items]
Credit facility agreement, future increases			$ 20,000,000
Paycheck Protection Program Loan [Member] | CARES Act Of 2020 [Member] | Potbelly Sandwich Works, LLC [Member]
Debt Instrument [Line Items]
Loan maturity period		5 years
Credit facility agreement, interest rate		1.00%
Paycheck Protection Program Loan [Member] | Harvest Small Business Finance L L C | Commercial Loan [Member] | Potbelly Sandwich Works, LLC [Member]
Debt Instrument [Line Items]
Loan amount		$ 10,000,000.0
Paycheck Protection Program Loan [Member] | Harvest Small Business Finance L L C | CARES Act Of 2020 [Member] | Fifth Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Credit facility agreement, amount outstanding				$ 2,800,000	$ 39,800,000
Revolving Credit Commitment [Member] | CARES Act Of 2020 [Member] | Fifth Credit Agreement Amendment [Member] | Minimum [Member]
Debt Instrument [Line Items]
Credit facility agreement, future increases	$ 40,000,000
Revolving Credit Commitment [Member] | CARES Act Of 2020 [Member] | Fifth Credit Agreement Amendment [Member] | Maximum [Member]
Debt Instrument [Line Items]
Credit facility agreement, future increases	$ 25,000,000
Eurodollar Loan [Member] | CARES Act Of 2020 [Member] | Fifth Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Debt instrument, increase in interest rate	5.00%
CBFR Loan [Member] | CARES Act Of 2020 [Member] | Fifth Credit Agreement Amendment [Member]
Debt Instrument [Line Items]
Debt instrument, increase in interest rate	2.75%

X

- 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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X

- Definition

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

+ References

No definition available.

+ Details

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X

- 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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X

- 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

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X

- Definition

Average amount borrowed under the credit facility during the period.

+ References

No definition available.

+ Details

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Period Type:	duration

X

- 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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X

- Definition

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

+ 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

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X

- 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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X

- 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

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X

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

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

+ Details

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