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Organization and Other Matters - Additional Information (Detail)
6 Months Ended
Jun. 30, 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] | Minimum [Member]  
Nature Of Business And Basis Of Presentation [Line Items]  
Number of shops franchisees operate 40