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Organization and Other Matters - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2019 Shop Subsidiary JointVenture
Nature Of Business And Basis Of Presentation [Line Items]
Number of wholly owned subsidiaries | Subsidiary	7
Number of joint ventures | JointVenture	7
Lease, practical expedients, package	false
Lease, practical expedient, use of hindsight	false
Minimum [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Number of shops Potbelly Corporation owns or operates	400
Ownership interest rate	51.00%
Maximum [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Ownership interest rate	80.00%
Middle East [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Number of shops franchisees operate	50

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Indicates (true false) whether practical expedient is elected to use hindsight in determining lease term and in assessing impairment of right-of-use asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 10
-Section 65
-Paragraph 1
-Subparagraph (j)
-URI http://asc.fasb.org/extlink&oid=113997351&loc=SL77916155-209984

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-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (j)
-URI http://asc.fasb.org/extlink&oid=113997351&loc=SL77916155-209984

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