| Document and Entity Information - USD ($) $ in Millions | 12 Months Ended | ||
| Dec. 29, 2019 | Jan. 26, 2020 | Jun. 30, 2019 | |
| Cover [Abstract] | |||
| Document Type | 10-K/A | ||
| Amendment Flag | true | ||
| Amendment Description | Potbelly Corporation (the “Company”, “Potbelly,” “we” and “our”) is filing this Amendment No. 1 on Form 10-K/A (this “Amendment”) to its Form 10-K for the fiscal year ended December 29, 2019, which was filed with the SEC on February 27, 2020 (the “Original Filing”).This Amendment is being filed for the purpose of providing the information required by Items 10 through 14 of Part III of Form 10-K. This information was previously omitted from the Original Filing in reliance on General Instruction G(3) to Form 10-K, which permits the above-referenced Items to be incorporated in the Annual Report on Form 10-K by reference from a definitive proxy statement, if such definitive proxy statement is filed no later than 120 days after the last day of the Company’s fiscal year on December 29, 2019, or April 27, 2020. A definitive proxy statement was not filed on or before April 27, 2020. Unless otherwise specifically noted to the contrary, the information provided in this Amendment is as of the date of the Original Filing.In accordance with Rule 12b-15 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), the cover page to the Original Filing and Items 10 through 14 of Part III of the Original Filing are hereby amended and restated in their entirety. In addition, pursuant to Rule 12b-15 under the Exchange Act, the Company is including Item 15 of Part IV, solely to file the certifications required under Section 302 of the Sarbanes-Oxley Act of 2002 with this Amendment.Except as described above, no other changes have been made to the Original Filing. This Amendment No. 1 does not affect any other section of the Original Filing not otherwise discussed herein and continues to speak as of the date of the Original Filing. The Company has not updated the disclosures contained in the Original Filing to reflect any events that occurred subsequent to the date of the Original Filing. Accordingly, this Amendment No. 1 should be read in conjunction with the Company’s other filings made with the SEC subsequent to the filing of the Original Filing. | ||
| Document Period End Date | Dec. 29, 2019 | ||
| Document Fiscal Year Focus | 2019 | ||
| Document Fiscal Period Focus | FY | ||
| Trading Symbol | PBPB | ||
| Entity Registrant Name | POTBELLY CORP | ||
| Entity Central Index Key | 0001195734 | ||
| Current Fiscal Year End Date | --12-29 | ||
| Entity Well-known Seasoned Issuer | No | ||
| Entity Current Reporting Status | Yes | ||
| Entity Voluntary Filers | No | ||
| Entity Filer Category | Accelerated Filer | ||
| Entity Small Business | false | ||
| Entity Emerging Growth Company | false | ||
| Entity Shell Company | false | ||
| Entity Common Stock, Shares Outstanding | 23,638,157 | ||
| Entity Public Float | $ 116.7 | ||
| Title of 12(b) Security | Common Stock, $0.01 par value | ||
| Entity File Number | 001-36104 | ||
| Entity Tax Identification Number | 36-4466837 | ||
| Entity Address, Address Line One | 111 N. Canal Street | ||
| Entity Address, Address Line Two | Suite 850 | ||
| Entity Address, City or Town | Chicago | ||
| Entity Address, State or Province | IL | ||
| Entity Incorporation, State or Country Code | DE | ||
| Entity Address, Postal Zip Code | 60606 | ||
| City Area Code | 312 | ||
| Local Phone Number | 951-0600 | ||
| Document Annual Report | true | ||
| Document Transition Report | false | ||
| Entity Interactive Data Current | Yes | ||
| Security Exchange Name | NASDAQ |
