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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 29, 2020	Apr. 26, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 29, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	PBPB
Security Exchange Name	NASDAQ
Entity Registrant Name	Potbelly Corporation
Entity Central Index Key	0001195734
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-27
Entity Filer Category	Accelerated Filer
Entity Shell Company	false
Entity Bankruptcy Proceedings, Reporting Current	true
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		23,684,000
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 Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 29, 2020	Dec. 29, 2019
Current assets
Cash and cash equivalents	$ 45,816	$ 18,806
Accounts receivable, net of allowances of $258 and $202 as of March 29, 2020 and December 29, 2019, respectively	2,651	4,257
Inventories	3,245	3,473
Prepaid expenses and other current assets	8,454	5,687
Total current assets	60,166	32,223
Property and equipment, net	73,006	79,032
Right-of-use assets for operating leases	208,239	211,988
Indefinite-lived intangible assets	3,404	3,404
Goodwill	2,222	2,222
Deferred expenses, net and other assets	4,032	4,010
Total assets	351,069	332,879
Current liabilities
Accounts payable	3,375	3,886
Accrued expenses	15,656	20,398
Short-term operating lease liabilities	29,701	29,319
Accrued income taxes	171	171
Debt from revolving credit facility	39,786
Total current liabilities	88,689	53,774
Long-term operating lease liabilities	202,902	206,726
Other long-term liabilities	3,274	3,210
Total liabilities	294,865	263,710
Commitments and contingencies (Note 10)
Equity
Common stock, $0.01 par value—authorized 200,000 shares; outstanding 23,684 and 23,638 shares as of March 29, 2020 and December 29, 2019, respectively	331	331
Additional paid-in-capital	435,768	435,278
Treasury stock, held at cost, 9,488 and 9,465 shares as of March 29, 2020, and December 29, 2019, respectively	(112,751)	(112,680)
Accumulated deficit	(267,422)	(254,081)
Total stockholders’ equity	55,926	68,848
Non-controlling interest	278	321
Total equity	56,204	69,169
Total liabilities and equity	$ 351,069	$ 332,879

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 29, 2020	Dec. 29, 2019
Statement Of Financial Position [Abstract]
Allowances on accounts receivable	$ 258	$ 202
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized	200,000,000	200,000,000
Common stock, outstanding	23,684,000	23,638,000
Treasury stock, shares	9,488,000	9,465,000

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019
Revenues
Total revenues	$ 87,590	$ 98,087
Sandwich shop operating expenses
Labor and related expenses	30,397	31,973
Occupancy expenses	15,028	14,377
Other operating expenses	12,765	12,145
General and administrative expenses	10,734	12,709
Depreciation expense	5,456	5,536
Pre-opening costs	64	10
Impairment and loss on disposal of property and equipment	5,957	82
Total expenses	104,575	102,810
Loss from operations	(16,985)	(4,723)
Interest expense	74	32
Loss before income taxes	(17,059)	(4,755)
Income tax expense (benefit)	(3,709)	13,619
Net loss	(13,350)	(18,374)
Net income (loss) attributable to non-controlling interest	(14)	65
Net loss attributable to Potbelly Corporation	$ (13,336)	$ (18,439)
Net loss per common share attributable to common stockholders:
Basic	$ (0.56)	$ (0.76)
Diluted	$ (0.56)	$ (0.76)
Weighted average shares outstanding:
Basic	23,646	24,133
Diluted	23,646	24,133
Product [Member]
Revenues
Total revenues	$ 86,961	$ 97,258
Sandwich shop operating expenses
Cost of goods sold, excluding depreciation	24,174	25,978
Franchise Royalties And Fees [Member]
Revenues
Total revenues	$ 629	$ 829

Condensed Consolidated Statements of Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in-Capital [Member]	Accumulated Deficit [Member]	Non-Controlling Interest [Member]
Beginning balance at Dec. 30, 2018	$ 95,533	$ 330	$ (108,372)	$ 432,771	$ (229,558)	$ 362
Beginning balance, common shares at Dec. 30, 2018		24,143
Cumulative impact \| ASU 2016-02 (Topic 842) [Member]	(531)				(531)
Net income (loss)	(18,374)				(18,439)	65
Stock-based compensation plans	170			170
Stock-based compensation plans, shares		33
Repurchases of common stock	(1,144)		(1,144)
Repurchases of common stock, shares		(135)
Treasury shares used for stock-based plans	(25)		(25)
Treasury shares used for stock-based plans, shares		(3)
Stock-based compensation expense	459			459
Ending balance at Mar. 31, 2019	76,088	$ 330	(109,541)	433,400	(248,528)	427
Ending balance, common shares at Mar. 31, 2019		24,038
Beginning balance at Dec. 29, 2019	$ 69,169	$ 331	(112,680)	435,278	(254,081)	321
Beginning balance, common shares at Dec. 29, 2019	23,638	23,638
Cumulative impact \| ASU 2016-13 (Topic 326) [Member]	$ (5)				(5)
Net income (loss)	(13,350)				(13,336)	(14)
Stock-based compensation plans, shares		68
Treasury shares used for stock-based plans	(71)		(71)
Treasury shares used for stock-based plans, shares		(22)
Distributions to non-controlling interest	(172)					(172)
Contributions from non-controlling interest	143					143
Stock-based compensation expense	490			490
Ending balance at Mar. 29, 2020	$ 56,204	$ 331	$ (112,751)	$ 435,768	$ (267,422)	$ 278
Ending balance, common shares at Mar. 29, 2020	23,684	23,684

Condensed Consolidated Statements of Equity (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019
ASU 2016-02 (Topic 842) [Member]
Cumulative impact tax	$ 2	$ 196

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income (loss)	$ (13,350)	$ (18,374)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	5,456	5,536
Noncash lease expense	7,295	7,829
Deferred income tax	5	13,580
Stock-based compensation expense	490	459
Asset impairment, store closure and disposal of property and equipment	6,236	87
Other operating activities	20	9
Changes in operating assets and liabilities:
Accounts receivable, net	1,620	(811)
Inventories	228	189
Prepaid expenses and other assets	(3,252)	1,455
Accounts payable	(767)	(130)
Operating lease liabilities	(7,653)	(7,860)
Accrued expenses and other liabilities	(4,144)	(4,342)
Net cash used in operating activities:	(7,816)	(2,373)
Cash flows from investing activities:
Purchases of property and equipment	(4,860)	(2,572)
Net cash used in investing activities:	(4,860)	(2,572)
Cash flows from financing activities:
Borrowings under credit facility	39,786
Proceeds from exercise of stock options		170
Employee taxes on certain stock-based payment arrangements	(71)	(25)
Treasury stock repurchases		(1,144)
Distributions to non-controlling interest	(172)
Contributions from non-controlling interest	143
Net cash provided by (used in) financing activities:	39,686	(999)
Net increase (decrease) in cash and cash equivalents	27,010	(5,944)
Cash and cash equivalents at beginning of period	18,806	19,775
Cash and cash equivalents at end of period	45,816	13,831
Supplemental cash flow information:
Income taxes paid	9	4
Interest paid	25	24
Supplemental non-cash investing and financing activities:
Unpaid liability for purchases of property and equipment	$ 1,091	$ 161

Organization and Other Matters

3 Months Ended

Mar. 29, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Other Matters

(1) Organization and Other Matters

Business

Potbelly Corporation (the “Company” or “Potbelly”), through its wholly owned subsidiaries, owns or operates more than 400 company-owned shops in the United States. Additionally, Potbelly franchisees operate over 40 shops in the United States.

Basis of Presentation

The unaudited condensed consolidated financial statements and notes herein should be read in conjunction with the audited consolidated financial statements of Potbelly Corporation and its subsidiaries and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 29, 2019. The unaudited condensed consolidated financial statements included herein have been prepared by the Company without audit, pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (the “SEC”) regarding interim financial reporting. Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) have been condensed or omitted pursuant to the SEC rules and regulations. In the opinion of management, all adjustments, which are of a normal and recurring nature (except as otherwise noted), that are necessary to present fairly the Company’s balance sheet as of March 29, 2020 and December 29, 2019, its statement of operations for the 13 weeks ended March 29, 2020 and March 31, 2019, the statement of equity for the 13 weeks ended March 29, 2020 and March 31, 2019, and its statement of cash flows for the 13 weeks ended March 29, 2020 and March 31, 2019 have been included. The consolidated statements of operations for the interim periods presented herein are not necessarily indicative of the results to be expected for the full year.

The Company does not have any components of other comprehensive income recorded within its consolidated financial statements and therefore, does not separately present a statement of comprehensive income in its condensed consolidated financial statements.

COVID-19

On January 30, 2020, the World Health Organization (“WHO”) announced a global health emergency because of a new strain of coronavirus ("COVID-19") and the risks to the international community as the virus spreads globally. On March 11, 2020, the WHO classified the COVID-19 outbreak as a pandemic, based on the rapid increase in exposure globally. In response to the pandemic, many states and jurisdictions in which we operate have issued stay-at-home orders and other measures aimed at slowing the spread of the coronavirus. While most of our company-owned shops remain open in accordance with guidance from local authorities, these measures resulted in us closing the vast majority our dining rooms and shifting to off-premise operations only, and we experienced a sudden and drastic decrease in revenues.

The disruption in operations and reduction in revenues have led the Company to consider the impact of the COVID-19 pandemic on the recoverability of its assets, including property and equipment, right-of-use assets for operating leases, goodwill and intangible assets, and others.

Due to the impact of the COVID-19 pandemic, the Company performed impairment analyses of its goodwill, intangible assets, and long-lived assets, which includes property and equipment and right-of-use assets for operating leases, as of March 29, 2020. The impairment assessments for both goodwill and indefinite lived intangible assets resulted in the conclusion that the fair value of these assets exceeded their carrying values. Accordingly, the Company did not record any impairment to its goodwill or indefinite-lived intangible assets during the thirteen weeks ended March 29, 2020. The Company recorded an impairment charge for its long-lived assets of $5.9 million for the 13 weeks ended March 29, 2020, primarily driven by the expected impact of the COVID-19 pandemic on future cash flows. The ultimate severity and longevity of the COVID-19 pandemic is unknown, and therefore, it is possible that impairments could be identified in future periods, and such amounts could be material. See Note 3 for further details.

The Company recognized an income tax benefit of $3.7 million for the thirteen weeks ended March 29, 2020 primarily due to the impact of the Coronavirus Aid, Relief and Economic Security Act (the “CARES Act”). The Company estimates that it will be able to obtain a tax refund of $3.7 million from the carryback of NOLs and a refund of prior AMT credits. See Note 5 for further details.

To preserve financial flexibility, the Company drew the $40.0 million of available capacity under its revolving credit facility. Due to the pandemic’s impact on revenues, the Company is in discussions with its lender regarding modifications to financial covenants related to the revolving credit facility. See Note 7 for further details.

The full impact of the COVID-19 outbreak continues to evolve as of the date of this report. Due to the rapid development and fluidity of this situation, the Company cannot determine the ultimate impact that the COVID-19 pandemic will have on its consolidated financial condition, liquidity, and future results of operations, and therefore any prediction as to the ultimate material adverse impact on the Company’s consolidated financial condition, liquidity, and future results of operations is uncertain.

Going Concern

Under ASC 205, Presentation of Financial Statements, the Company is required to consider and has evaluated whether there is substantial doubt that it has the ability to meet its obligations within one year from the financial statement issuance date. This assessment also includes the Company’s consideration of any management plans to alleviate such doubts. The conditions described above related to the COVID-19 pandemic have had a material adverse impact on the Company’s revenues, profitability, and cash flows. Because of these conditions, the Company has concluded that it is probable that it will not be in compliance with certain financial covenants of the Credit Agreement Amendment, which are further described in Note 7, for a period of one year from the financial statement issuance date. The probable inability of the Company to meet its current covenant requirements raises substantial doubt on the Company’s ability to meet its obligations within one year from the financial statement issuance date and to continue as a going concern. If the Company is unable to maintain compliance with the covenants contained in the current Credit Agreement, it may be unable to make additional borrowings on any undrawn amounts and may be required to repay its then outstanding borrowings. The Company is in continued negotiations with its current lender and expects further amendments to the Credit Agreement as needed to maintain compliance with future financial covenants, but we cannot make any assurances regarding the likelihood, certainty or exact timing of further amendments to the Credit Agreement. The Company is also evaluating various alternatives to improve its liquidity, including but not limited to, lease concessions and deferrals, further reductions of operating and capital expenditures, and raising additional capital.

The condensed consolidated financial statements included in this interim report on Form 10-Q do not include any adjustments that might result from the outcome of this uncertainty.

Principles of Consolidation

The unaudited condensed consolidated financial statements include the accounts of Potbelly Corporation; its wholly owned subsidiary, Potbelly Illinois, Inc. (“PII”); PII’s wholly owned subsidiaries, Potbelly Franchising, LLC and Potbelly Sandwich Works, LLC (“LLC”); seven of LLC’s wholly owned subsidiaries and LLC’s seven joint ventures, collectively, the “Company.” All intercompany balances and transactions have been eliminated in consolidation. For consolidated joint ventures, non-controlling interest represents a non-controlling partner’s share of the assets, liabilities and operations related to the seven joint venture investments. The Company has ownership interests ranging from 51-80% in these consolidated joint ventures.

Fiscal Year

The Company uses a 52/53-week fiscal year that ends on the last Sunday of the calendar period. Approximately every five or six years a 53rd week is added. Fiscal year 2020 and 2019 both consist of 52 weeks. The fiscal quarters ended March 29, 2020 and March 31, 2019 each consisted of 13 weeks.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Significant estimates include amounts for long-lived assets and income taxes. Actual results could differ from those estimates.

Recent Accounting Pronouncements

On December 30, 2019, the Company adopted Accounting Standard Update No. 2016-13, Financial Instruments—Credit Losses (Topic 326). This pronouncement requires the measurement and recognition of expected credit losses on financial instruments. ASU 2016-13 replaces the existing incurred loss model with a forward-looking expected credit loss model that requires consideration of a broader range of information to estimate credit losses. The Company recorded a net reduction of $5 thousand to opening accumulated deficit as of December 30, 2019, due to the cumulative impact of adopting Topic 326.

Revenue

3 Months Ended

Mar. 29, 2020

Revenue From Contract With Customer [Abstract]

Revenue

(2) Revenue

The Company primarily earns revenue at a point in time for sandwich shop sales which can occur in person at the shop, over our web or app platform, or through a third-party platform. Revenue is recorded net of sales-related taxes collected from customers. The payment on these sales is due at the time of the customer’s purchase. The Company also receives royalties from franchisees on their respective sales, which are recognized at the point in time the sale is made and invoiced weekly. Potbelly also records revenue from sales over time related to upfront franchise fees, gift card redemptions and breakage. For the 13 weeks ended March 29, 2020, revenue recognized from all revenue sources on point in time sales was $87.5 million, and revenue recognized from sales over time was $0.1 million. For the 13 weeks ended March 31, 2019, revenue recognized from all revenue sources on point in time sales was $97.8 million, and revenue recognized from sales over time was $0.3 million.

Franchise Revenue

Potbelly licenses intellectual property and trademarks to franchisees through franchise agreements. As part of these franchise agreements, Potbelly receives an upfront payment from the franchisee, which the Company recognizes over the term of the franchise agreement. The Company records a contract liability for the unearned portion of the upfront franchise payments.

Gift Card Redemptions / Breakage Revenue

Potbelly sells gift cards to customers, records the sale as a contract liability and recognizes the associated revenue as the gift card is redeemed. A portion of these gift cards are not redeemed by the customer, which is recognized by the Company as revenue as a percentage of customers gift card redemptions. The expected breakage amount recognized is determined by a historical data analysis on gift card redemption patterns.

Contract Liabilities

As described above, the Company records current and noncurrent contract liabilities for upfront franchise fees and gift cards. There are no other contract liabilities or contract assets recorded by the Company. The opening and closing balances of the Company’s current and noncurrent contract liabilities from contracts with customers were as follows:

	Current Contract Liability			Noncurrent Contract Liability
	(Thousands)			(Thousands)
Beginning balance as of December 30, 2019	$	(1,594	)	$	(2,054	)
Ending balance as of March 29, 2020		(1,264	)		(1,984	)
Decrease in contract liability	$	(330	)	$	(70	)

The aggregate value of remaining performance obligations on outstanding contracts was $3.2 million as of March 29, 2020. The Company expects to recognize revenue related to contract liabilities as follows (in thousands), which may vary based upon franchise activity as well as gift card redemption patterns:

Years Ending	Amount
2020	$	942
2021		302
2022		240
2023		206
2024		174
Thereafter		1,384
Total revenue recognized	$	3,248

For the 13 weeks ended March 29, 2020, the amount of revenue recognized related to the December 30, 2019 liability ending balance was $0.5 million. For the 13 weeks ended March 31, 2019, the amount of revenue recognized related to the December 30, 2018 liability ending balance was $0.8 million. This revenue related to the recognition of gift card redemptions and upfront franchise fees. For the 13 weeks ended March 29, 2020 and March 31, 2019, the Company did not recognize any revenue from obligations satisfied (or partially satisfied) in prior periods.

Fair Value Measurement

3 Months Ended

Mar. 29, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurement

(3) Fair Value Measurement

The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable and all other current liabilities approximate fair values due to the short maturities of these balances.

The Company assesses potential impairments to its long-lived assets, which includes property and equipment and lease right-of-use assets, on a quarterly basis or whenever events or circumstances indicate that the carrying amount of an asset may not be recoverable. Shop-level assets and right-of-use assets are grouped at the individual shop-level for the purpose of the impairment assessment. Recoverability of an asset group is measured by a comparison of the carrying amount of an asset group to its estimated undiscounted future cash flows expected to be generated by the asset group. If the carrying amount of the asset group exceeds its estimated undiscounted future cash flows, an impairment charge is recognized as the amount by which the carrying amount of the asset group exceeds the fair value of the asset group. The fair value of the shop assets is determined using the discounted future cash flow method of anticipated cash flows through the shop’s lease-end date using fair value measurement inputs classified as Level 3. The fair value of right-of-use assets is estimated using market comparative information for similar properties. Level 3 inputs are derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. After performing a periodic review of the Company’s shops during the 13 weeks ended March 29, 2020, it was determined that indicators of impairment were present for certain shops as a result of continued underperformance. The Company performed an impairment analysis related to these shops and recorded an impairment charge of $5.9 million for the 13 weeks ended March 29, 2020, primarily driven by the expected impact of the COVID-19 pandemic on future cash flows. The ultimate severity and longevity of the COVID-19 pandemic is unknown, and therefore, it is possible that impairments could be identified in future periods, and such amounts could be material. After performing a periodic review of the Company’s shops during the 13 weeks ended March 31, 2019, it was determined that there were no indicators of impairment for the quarter ended March 31, 2019 and accordingly, the Company recorded no impairment charge for the 13 weeks ended March 31, 2019.

Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis

Assets recognized or disclosed at fair value on the consolidated financial statements on a nonrecurring basis include items such as leasehold improvements, property and equipment, operating lease assets, goodwill, and other intangible assets. These assets are measured at fair value if determined to be impaired.

The Company reviews indefinite-lived intangible assets, which includes goodwill and tradenames, annually at fiscal year-end for impairment or more frequently if events or circumstances indicate that the carrying value may not be recoverable. Due to the recent impact of the COVID-19 pandemic to the global economy, including but not limited to, the volatility of the Company's stock price as well as that of its competitors, declining sales at the Company's restaurants and the challenging environment for the restaurant industry generally, the Company determined that there were indicators of potential impairment of its goodwill and indefinite-lived intangible assets during the thirteen weeks ended March 29, 2020. As such, the Company performed an impairment assessment for both goodwill and indefinite lived intangible assets and concluded that the fair value of these assets exceeded their carrying values. Accordingly, the Company did not record any impairment to its goodwill or indefinite-lived intangible assets during the thirteen weeks ended March 29, 2020. The ultimate severity and longevity of the COVID-19 pandemic is unknown, and therefore, it is possible that impairments could be identified in future periods, and such amounts could be material.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Loss Per Share

3 Months Ended

Mar. 29, 2020

Earnings Per Share [Abstract]

Loss Per Share

(4) Loss Per Share

Basic and diluted income per common share attributable to common stockholders are calculated using the weighted average number of common shares outstanding for the period. Diluted income per common share attributable to common stockholders is computed by dividing the income allocated to common stockholders by the weighted average number of fully diluted common shares outstanding. In periods of a net loss, no potential common shares are included in diluted shares outstanding as the effect is anti-dilutive. For the 13 weeks ended March 29, 2020, and March 31, 2019, the Company had a loss per share, and therefore potentially dilutive shares were excluded from the calculation.

The following table summarizes the loss per share calculation:

	For the 13 Weeks Ended
	March 29,			March 31,
	2020			2019
Net loss attributable to Potbelly Corporation	$	(13,336	)	$	(18,439	)
Weighted average common shares outstanding-basic		23,646			24,133
Plus: Effect of potential stock options exercise		—			—
Weighted average common shares outstanding-diluted		23,646			24,133
Loss per share available to common stockholders-basic	$	(0.56	)	$	(0.76	)
Loss per share available to common stockholders-diluted	$	(0.56	)	$	(0.76	)
Potentially dilutive shares that are considered anti-dilutive:
Common share options		2,294			2,387

Income Taxes

3 Months Ended

Mar. 29, 2020

Income Tax Disclosure [Abstract]

Income Taxes

(5) Income Taxes

On March 27, 2020, the CARES Act was enacted into law. The CARES Act is a tax and spending package intended to provide economic relief to address the impact of the COVID-19 pandemic. The CARES Act includes several significant business tax provisions that, among other things, would eliminate the taxable income limit for certain net operating losses (“NOLs”) and allow businesses to carry back NOLs arising in 2018, 2019, and 2020 to the five prior tax years, accelerate refunds of previously generated corporate alternative minimum tax (“AMT”) credits, loosen the business interest limitation under section 163(j), and fix the qualified improvement property regulations in the 2017 Tax Cuts and Jobs Act. As a result of the CARES Act, the Company estimates that it will be able to obtain a tax refund of $3.7 million from the carryback of NOLs and a refund of prior AMT credits.

The interim tax provision is determined using an estimated annual effective tax rate and is adjusted for discrete taxable events that occur during the quarter. The Company recognized an income tax benefit of $3.7 million for the thirteen weeks ended March 29, 2020 primarily due to the impact of the Cares Act discussed above. The Company recorded a tax expense of $13.6 million for the thirteen weeks ended March 31, 2019 due to the Company recording a non-cash charge to income tax expense for the recognition of a full valuation allowance against its net deferred tax assets. The Company continues to record a valuation allowance against all of its deferred tax assets as March 29, 2020. The Company did not provide for an income tax benefit on its pre-tax loss for the 13 weeks ended March 29, 2020 and March 31, 2019.

The Company regularly assesses the need for a valuation allowance related to its deferred tax assets, which includes consideration of both positive and negative evidence related to the likelihood of realization of such deferred tax assets to determine, based on the weight of the available evidence, whether it is more-likely-than-not that some or all of its deferred tax assets will not be realized. In its assessment, the Company considers recent financial operating results, projected future taxable income, the reversal of existing taxable differences, and tax planning strategies. The Company recorded a full valuation allowance against its net deferred tax assets during the 13 weeks ended March 31, 2019. The Company recorded a non-cash charge to income tax expense of $13.6 million related to the recognition of the valuation allowance during the first quarter of 2019 and continue to record a valuation allowance against all of our deferred tax assets as of March 29, 2020. The Company will continue to assess the likelihood of the realization of its deferred tax assets and the valuation allowance will be adjusted accordingly

Leases

3 Months Ended

Mar. 29, 2020

Leases [Abstract]

Leases

(6) Leases

We determine if a contract contains a lease at inception. The Company leases retail shops, warehouse and office space under operating leases. For leases with renewal periods at the Company’s option, the Company determines the expected lease period based on whether the renewal of any options are reasonably assured at the inception of the lease.

Operating lease assets and liabilities are recognized at the lease commencement date. Operating lease liabilities represent the present value of lease payments not yet paid. Operating lease assets represent our right to use an underlying asset and are based upon the operating lease liabilities adjusted for prepayments or accrued lease payments, initial direct costs, lease incentives, and impairment of operating lease assets. To determine the present value of lease payments not yet paid, we estimate incremental secured borrowing rates corresponding to the maturities of the leases. The Company estimates this rate based on prevailing financial market conditions, comparable company and credit analysis, and management judgment.

We recognize expense for these leases on a straight-line basis over the lease term. Additionally, tenant incentives used to fund leasehold improvements are recognized when earned and reduce our right-of-use asset related to the lease. These are amortized through the right-of-use asset as reductions of expense over the lease term.

Operating lease term and discount rate were as follows:

	March 29,			March 31,
	2020			2019
Weighted average remaining lease term (years)	8.33			8.90
Weighted average discount rate		7.90	%		8.01	%

Certain of the Company’s operating lease agreements include variable payments that are passed through by the landlord, such as common area maintenance and real estate taxes, as well as variable payments based on percentage rent for certain of our shops. Pass-through charges and payments based on percentage rent are included within variable lease cost.

The components of lease cost were as follows:

		13 weeks ending		13 weeks ending
		March 29,		March 31,
	Classification	2020		2019
Operating lease cost	Occupancy and General and administrative expenses		11,770		10,995
Variable lease cost	Occupancy		3,322		3,504
Total lease cost		$	15,092	$	14,499

Supplemental disclosures of cash flow information related to leases were as follows:

	13 weeks ending		13 weeks ending
	March 29,		March 31,
	2020		2019
Operating cash flows rent paid for operating lease liabilities		11,979		11,938
Operating right-of-use assets obtained in exchange for new operating lease liabilities		5,534		922
Reduction in operating right-of-use assets due to lease terminations		1,439		—

As of March 29, 2020, the Company had no real estate leases entered into that had not yet commenced.

Maturities of lease liabilities were as follows as of March 29, 2020:

	Operating Leases
Remainder of 2020		34,954
2021		44,610
2022		39,071
2023		34,321
2024		31,180
2025		28,836
Thereafter		112,902
Total lease payments		325,874
Less: imputed interest		(93,271	)
Present value of lease liabilities	$	232,603

Debt and Credit Facilities

3 Months Ended

Mar. 29, 2020

Debt Disclosure [Abstract]

Debt and Credit Facilities

(7) Debt and Credit Facilities

On August 7, 2019, the Company entered into a second amended and restated revolving credit facility agreement (the "Credit Agreement") with JPMorgan Chase Bank, N.A. (“JPMorgan”) that expires in July 2022. The Credit Agreement amends and restates that certain amended and restated revolving credit facility agreement, dated as of December 9, 2015, and amended on May 3, 2019 (collectively, the "Prior Credit Agreement") with JPMorgan. The Credit Agreement provides, among other things, for a revolving credit facility in a maximum principal amount $40 million, with possible future increases of up to $20 million under an expansion feature. Borrowings under the credit facility generally bear interest at the Company’s option at either (i) a eurocurrency rate determined by reference to the applicable LIBOR rate plus a margin ranging from 1.25% to 1.75% or (ii) a prime rate as announced by JP Morgan plus a margin ranging from 0.00% to 0.50%. The applicable margin is determined based upon the Company’s consolidated total leverage ratio. On the last day of each calendar quarter, the Company is required to pay a commitment fee of 0.20% per annum in respect of any unused commitments under the credit facility. So long as certain total leverage ratios, EBITDA thresholds and minimum liquidity requirements are met and no default or event of default has occurred or would result, there is no limit on the “restricted payments” (primarily distributions and equity repurchases) that the Company may make, provided that proceeds of the loans under the Credit Agreement may not be used for purposes of making restricted payments.

On March 17, 2020, the Company fully drew the available capacity of $39.8 million under its Revolving Credit Facility as a precautionary measure in order to increase its cash position and preserve financial flexibility in light of current uncertainty in the global markets resulting from the COVID-19 pandemic. In accordance with the terms of its Revolving Credit Facility, the proceeds from these borrowings may in the future be used for working capital, general corporate or other permitted purposes. As of March 29, 2020, the Company had $39.8 million outstanding under the Credit Agreement. There were no borrowings outstanding as of March 31, 2019.

The Credit Agreement was subsequently amended as of May 15, 2020 (the “Credit Agreement Amendment”) to, among other things (i) change the maturity date from July 31, 2022 to March 31, 2022; (ii) eliminate the $20.0 million expansion feature; (iii) amend the interest rate to the Company’s option at either (a) a eurocurrency rate determined by reference to the applicable LIBOR rate with a 1.00% floor plus a margin of 5.00% or (b) a prime rate as announced by JP Morgan plus 4.00%; (iv) amend the commitment fee to 1.00% per annum in respect of any unused commitments under the credit facility; (v) implement additional restrictions on restricted payments, acquisitions and other indebtedness; and (vi) implement additional financial covenants. Per the terms of the Credit Agreement Amendment, the Company repaid $15.0 million of its outstanding borrowing at the signing of the Credit Agreement Amendment, and may re-borrow this $15.0 million when its cash balances held by JP Morgan declines below $28.0 million. Lastly, the Company is required to pay an upfront fee of 1% of the outstanding loan balance within fifteen business days of the signing of the Credit Agreement Amendment.

The Credit Agreement Amendment includes financial covenants that require the Company to maintain minimum liquidity levels, minimum building adjusted EBITDA, maximum total debt to adjusted EBITDA and a minimum trailing twelve months (“TTM”) adjusted EBITDA. The Company is required to maintain (i) a minimum liquidity level of $45.0 million at April 30, 2020 and $32.5 million at May 31, 2020; (ii) a minimum building adjusted EBITDA of ($8.5) million for April 2020 and ($16.0) million for the period of April 2020 through May 2020; (iii) a maximum total debt to adjusted EBITDA ratio of 2.25 to 1.00 beginning June 30, 2020; and (iv) a minimum TTM adjusted EBITDA of $16.0 million beginning June 30, 2020, $15.0 million beginning September 30, 2020 and $17.0 million beginning September 30, 2021. Compliance with the financial covenants was waived for March 29, 2020 as part of the Credit Agreement Amendment. The Company expects that it will be in compliance with the revised covenants for the April and May 2020 reporting periods. The Company concluded that without any additional changes, it would likely not meet the maximum total debt to adjusted EBITDA and/or the minimum TTM adjusted EBITDA requirements beginning with the month of June 2020, in which case the lenders would have the ability to demand repayment of the outstanding debt at such time. Accordingly, the outstanding balance is presented as a current liability as of March 29, 2020 based on the guidance in ASC 470, Debt.

Capital Stock

3 Months Ended

Mar. 29, 2020

Equity [Abstract]

Capital Stock

(8) Capital Stock

On May 8, 2018, the Company announced that its Board of Directors authorized a stock repurchase program for up to $65.0 million of its outstanding common stock. The program permits the Company, from time to time, to purchase shares in the open market (including in pre-arranged stock trading plans in accordance with the guidelines specified in Rule 10b5-1 under the Securities and Exchange Act of 1934, as amended) or in privately negotiated transactions. The number of common shares actually repurchased, and the timing and price of repurchases, will depend upon market conditions, SEC requirements and other factors. Purchases may be started or stopped at any time without prior notice depending on market conditions and other factors. For the 13 weeks ended March 29, 2020, the Company did not repurchase any shares of its common stock. Due to the COVID-19 pandemic, the Company does not have plans to repurchase any common stock under its share repurchase program at this time. For the 13 weeks ended March 31, 2019, the Company repurchased 135,000 shares of its common stock for approximately $1.1 million under the stock repurchase program, including cost and commission, in open market transactions. Repurchased shares are included as treasury stock in the condensed consolidated balance sheets and the condensed consolidated statements of equity.

Stock-Based Compensation

3 Months Ended

Mar. 29, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

(9) Stock-Based Compensation

Stock options

The Company has awarded stock options to certain employees of the Company and certain non-employee members of its Board of Directors. The grants generally vest over a four-year period. The fair value of stock options is determined using the Black-Scholes option pricing model. There were no stock options granted during the 13 weeks ended March 29, 2020.

A summary of stock option activity for the 13 weeks ended March 29, 2020 is as follows:

Options	Shares (Thousands)			Weighted Average Exercise Price		Aggregate Intrinsic Value (Thousands)		Weighted Average Remaining Term (Years)
Outstanding—December 29, 2019		1,774		$	11.34	$	—		4.33
Granted		—			—
Exercised		—			—
Canceled		(33	)		10.51
Outstanding—March 29, 2020		1,741			11.35	$	—		4.01
Exercisable—March 29, 2020		1,563		$	11.12	$	—		3.60

Stock-based compensation related to stock options is measured at the grant date based on the calculated fair value of the award, and is recognized as expense over the requisite employee service period, which is generally the vesting period of the grant with a corresponding increase to additional paid-in capital. For the 13 weeks ended March 29, 2020, the Company recognized stock-based compensation expense related to stock options of $0.2 million. For the 13 weeks ended March 31, 2019, the Company recognized stock-based compensation expense related to stock options of $0.3 million. As of March 29, 2020, unrecognized stock-based compensation expense for stock options was $0.6 million, which will be recognized through fiscal year 2022. The Company records stock-based compensation expense within general and administrative expenses in the condensed consolidated statements of operations.

Restricted stock units

The Company awards restricted stock units (“RSUs”) to certain employees of the Company and certain non-employee members of its Board of Directors. The Board of Director grants have a vesting schedule of 50% on the first anniversary of the grant date and 50% on the second anniversary of the grant date. The employee grants vest in one-third increments over a three-year period. For the 13 weeks ended March 29, 2020, the Company recognized stock-based compensation expense related to RSUs of $0.3 million. For the 13 weeks ended March 31, 2019, the Company recognized stock-based compensation expense related to RSUs of $0.2 million. As of March 29, 2020, unrecognized stock-based compensation expense for RSUs was $1.9 million, which will be recognized though fiscal year 2023.

A summary of RSU activity for the 13 weeks ended March 29, 2020 is as follows:

RSUs	Number of RSUs (Thousands)			Weighted Average Fair Value per Share
Non-vested as of December 29, 2019		463		$	7.59
Granted		158			3.88
Vested		(68	)		3.18
Canceled		—			—
Non-vested as of March 29, 2020		553		$	6.38

Performance stock units

The Company awards performance share units (“PSUs”) to eligible employees; the PSUs are subject to service and performance vesting conditions. In March 2019 the Company issued 188,414 PSUs with a grant date fair value of $8.46 per share. The PSUs will vest based on the Company’s achievement of certain targets related to adjusted EBITDA and same store sales goals. The PSUs will vest fully on the third anniversary of the grant date. The quantity of shares that will vest ranges from 0% to 200% of the targeted number of shares. If the defined minimum targets are not met, then no shares will vest. For the 13 weeks ended March 29, 2020 and March 31, 2019, no expense was recognized related to PSUs.

Commitments and Contingencies

3 Months Ended

Mar. 29, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

(10) Commitments and Contingencies

The Company is subject to legal proceedings, claims and liabilities, such as employment-related claims and slip and fall cases, which arise in the ordinary course of business and are generally covered by insurance. In the opinion of management, the amount of ultimate liability with respect to those actions should not have a material adverse impact on the Company’s financial position or results of operations and cash flows.

In October 2017, plaintiffs filed a purported collective and class action lawsuit (the “Complaint”) in the United States District Court for the Southern District of New York against the Company alleging violations of the Fair Labor Standards Act (FLSA) and New York Labor Law (NYLL). The plaintiffs allege that the Company violated the FLSA and NYLL by not paying overtime compensation to our assistant managers and violated NYLL by not paying spread-of-hours pay. The Complaint was brought as a nationwide “collective action” under the FLSA and as a “class action” under NYLL. Since the filing of the Complaint, the plaintiffs filed a proposed amended complaint removing the NYLL class claim, but adding a proposed Illinois state law class action. In May 2019, the parties participated in a mediation and resolved the claims, which received final court approval on February 4, 2020. All charges related to the claims are reflected in the statement of operations.

Subsequent Events

3 Months Ended

Mar. 29, 2020

Subsequent Events [Abstract]

Subsequent Events

(11) Subsequent Events

Paycheck Protection Program Loan

On April 10, 2020, Potbelly Sandwich Works, LLC, an indirect subsidiary of the Company, was granted a loan (the “Loan”) from JPMorgan Chase Bank, N.A. in the aggregate amount of $10.0 million, pursuant to the Paycheck Protection Program under Division A, Title I of the CARES Act, which was enacted March 27, 2020. On April 28, 2020, the Company repaid the $10.0 million proceeds from the loan.

Credit Facility

On May 15, 2020, the Company entered in to an amendment to its Credit Agreement. See Note 7 for further details.

Organization and Other Matters (Policies)	3 Months Ended
Organization and Other Matters (Policies)	Mar. 29, 2020
Accounting Policies [Abstract]
Business	Business Potbelly Corporation (the “Company” or “Potbelly”), through its wholly owned subsidiaries, owns or operates more than 400 company-owned shops in the United States. Additionally, Potbelly franchisees operate over 40 shops in the United States.
Basis of Presentation	Basis of Presentation The unaudited condensed consolidated financial statements and notes herein should be read in conjunction with the audited consolidated financial statements of Potbelly Corporation and its subsidiaries and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 29, 2019. The unaudited condensed consolidated financial statements included herein have been prepared by the Company without audit, pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (the “SEC”) regarding interim financial reporting. Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) have been condensed or omitted pursuant to the SEC rules and regulations. In the opinion of management, all adjustments, which are of a normal and recurring nature (except as otherwise noted), that are necessary to present fairly the Company’s balance sheet as of March 29, 2020 and December 29, 2019, its statement of operations for the 13 weeks ended March 29, 2020 and March 31, 2019, the statement of equity for the 13 weeks ended March 29, 2020 and March 31, 2019, and its statement of cash flows for the 13 weeks ended March 29, 2020 and March 31, 2019 have been included. The consolidated statements of operations for the interim periods presented herein are not necessarily indicative of the results to be expected for the full year. The Company does not have any components of other comprehensive income recorded within its consolidated financial statements and therefore, does not separately present a statement of comprehensive income in its condensed consolidated financial statements.
COVID-19	COVID-19 On January 30, 2020, the World Health Organization (“WHO”) announced a global health emergency because of a new strain of coronavirus ("COVID-19") and the risks to the international community as the virus spreads globally. On March 11, 2020, the WHO classified the COVID-19 outbreak as a pandemic, based on the rapid increase in exposure globally. In response to the pandemic, many states and jurisdictions in which we operate have issued stay-at-home orders and other measures aimed at slowing the spread of the coronavirus. While most of our company-owned shops remain open in accordance with guidance from local authorities, these measures resulted in us closing the vast majority our dining rooms and shifting to off-premise operations only, and we experienced a sudden and drastic decrease in revenues. The disruption in operations and reduction in revenues have led the Company to consider the impact of the COVID-19 pandemic on the recoverability of its assets, including property and equipment, right-of-use assets for operating leases, goodwill and intangible assets, and others. Due to the impact of the COVID-19 pandemic, the Company performed impairment analyses of its goodwill, intangible assets, and long-lived assets, which includes property and equipment and right-of-use assets for operating leases, as of March 29, 2020. The impairment assessments for both goodwill and indefinite lived intangible assets resulted in the conclusion that the fair value of these assets exceeded their carrying values. Accordingly, the Company did not record any impairment to its goodwill or indefinite-lived intangible assets during the thirteen weeks ended March 29, 2020. The Company recorded an impairment charge for its long-lived assets of $5.9 million for the 13 weeks ended March 29, 2020, primarily driven by the expected impact of the COVID-19 pandemic on future cash flows. The ultimate severity and longevity of the COVID-19 pandemic is unknown, and therefore, it is possible that impairments could be identified in future periods, and such amounts could be material. See Note 3 for further details. The Company recognized an income tax benefit of $3.7 million for the thirteen weeks ended March 29, 2020 primarily due to the impact of the Coronavirus Aid, Relief and Economic Security Act (the “CARES Act”). The Company estimates that it will be able to obtain a tax refund of $3.7 million from the carryback of NOLs and a refund of prior AMT credits. See Note 5 for further details. To preserve financial flexibility, the Company drew the $40.0 million of available capacity under its revolving credit facility. Due to the pandemic’s impact on revenues, the Company is in discussions with its lender regarding modifications to financial covenants related to the revolving credit facility. See Note 7 for further details. The full impact of the COVID-19 outbreak continues to evolve as of the date of this report. Due to the rapid development and fluidity of this situation, the Company cannot determine the ultimate impact that the COVID-19 pandemic will have on its consolidated financial condition, liquidity, and future results of operations, and therefore any prediction as to the ultimate material adverse impact on the Company’s consolidated financial condition, liquidity, and future results of operations is uncertain.
Going Concern	Going Concern Under ASC 205, Presentation of Financial Statements, the Company is required to consider and has evaluated whether there is substantial doubt that it has the ability to meet its obligations within one year from the financial statement issuance date. This assessment also includes the Company’s consideration of any management plans to alleviate such doubts. The conditions described above related to the COVID-19 pandemic have had a material adverse impact on the Company’s revenues, profitability, and cash flows. Because of these conditions, the Company has concluded that it is probable that it will not be in compliance with certain financial covenants of the Credit Agreement Amendment, which are further described in Note 7, for a period of one year from the financial statement issuance date. The probable inability of the Company to meet its current covenant requirements raises substantial doubt on the Company’s ability to meet its obligations within one year from the financial statement issuance date and to continue as a going concern. If the Company is unable to maintain compliance with the covenants contained in the current Credit Agreement, it may be unable to make additional borrowings on any undrawn amounts and may be required to repay its then outstanding borrowings. The Company is in continued negotiations with its current lender and expects further amendments to the Credit Agreement as needed to maintain compliance with future financial covenants, but we cannot make any assurances regarding the likelihood, certainty or exact timing of further amendments to the Credit Agreement. The Company is also evaluating various alternatives to improve its liquidity, including but not limited to, lease concessions and deferrals, further reductions of operating and capital expenditures, and raising additional capital. The condensed consolidated financial statements included in this interim report on Form 10-Q do not include any adjustments that might result from the outcome of this uncertainty.
Principles of Consolidation	Principles of Consolidation The unaudited condensed consolidated financial statements include the accounts of Potbelly Corporation; its wholly owned subsidiary, Potbelly Illinois, Inc. (“PII”); PII’s wholly owned subsidiaries, Potbelly Franchising, LLC and Potbelly Sandwich Works, LLC (“LLC”); seven of LLC’s wholly owned subsidiaries and LLC’s seven joint ventures, collectively, the “Company.” All intercompany balances and transactions have been eliminated in consolidation. For consolidated joint ventures, non-controlling interest represents a non-controlling partner’s share of the assets, liabilities and operations related to the seven joint venture investments. The Company has ownership interests ranging from 51-80% in these consolidated joint ventures.
Fiscal Year	Fiscal Year The Company uses a 52/53-week fiscal year that ends on the last Sunday of the calendar period. Approximately every five or six years a 53rd week is added. Fiscal year 2020 and 2019 both consist of 52 weeks. The fiscal quarters ended March 29, 2020 and March 31, 2019 each consisted of 13 weeks.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Significant estimates include amounts for long-lived assets and income taxes. Actual results could differ from those estimates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements On December 30, 2019, the Company adopted Accounting Standard Update No. 2016-13, Financial Instruments—Credit Losses (Topic 326). This pronouncement requires the measurement and recognition of expected credit losses on financial instruments. ASU 2016-13 replaces the existing incurred loss model with a forward-looking expected credit loss model that requires consideration of a broader range of information to estimate credit losses. The Company recorded a net reduction of $5 thousand to opening accumulated deficit as of December 30, 2019, due to the cumulative impact of adopting Topic 326.

Revenue (Tables)

3 Months Ended

Mar. 29, 2020

Revenue From Contract With Customer [Abstract]

Summary of Current and Noncurrent Contract Liabilities from Contracts with Customers

The opening and closing balances of the Company’s current and noncurrent contract liabilities from contracts with customers were as follows:

	Current Contract Liability			Noncurrent Contract Liability
	(Thousands)			(Thousands)
Beginning balance as of December 30, 2019	$	(1,594	)	$	(2,054	)
Ending balance as of March 29, 2020		(1,264	)		(1,984	)
Decrease in contract liability	$	(330	)	$	(70	)

Summary of Expected Revenue Recognition Related to Contract Liabilities

The Company expects to recognize revenue related to contract liabilities as follows (in thousands), which may vary based upon franchise activity as well as gift card redemption patterns:

Years Ending	Amount
2020	$	942
2021		302
2022		240
2023		206
2024		174
Thereafter		1,384
Total revenue recognized	$	3,248

Loss Per Share (Tables)

3 Months Ended

Mar. 29, 2020

Earnings Per Share [Abstract]

Summary of Loss Per Share Calculation

The following table summarizes the loss per share calculation:

	For the 13 Weeks Ended
	March 29,			March 31,
	2020			2019
Net loss attributable to Potbelly Corporation	$	(13,336	)	$	(18,439	)
Weighted average common shares outstanding-basic		23,646			24,133
Plus: Effect of potential stock options exercise		—			—
Weighted average common shares outstanding-diluted		23,646			24,133
Loss per share available to common stockholders-basic	$	(0.56	)	$	(0.76	)
Loss per share available to common stockholders-diluted	$	(0.56	)	$	(0.76	)
Potentially dilutive shares that are considered anti-dilutive:
Common share options		2,294			2,387

Leases (Tables)

3 Months Ended

Mar. 29, 2020

Leases [Abstract]

Operating Lease Term and Discount Rate

Operating lease term and discount rate were as follows:

	March 29,			March 31,
	2020			2019
Weighted average remaining lease term (years)	8.33			8.90
Weighted average discount rate		7.90	%		8.01	%

Components of Lease Cost

The components of lease cost were as follows:

		13 weeks ending		13 weeks ending
		March 29,		March 31,
	Classification	2020		2019
Operating lease cost	Occupancy and General and administrative expenses		11,770		10,995
Variable lease cost	Occupancy		3,322		3,504
Total lease cost		$	15,092	$	14,499

Supplemental Disclosures of Cash Flow Information Related to Leases

Supplemental disclosures of cash flow information related to leases were as follows:

	13 weeks ending		13 weeks ending
	March 29,		March 31,
	2020		2019
Operating cash flows rent paid for operating lease liabilities		11,979		11,938
Operating right-of-use assets obtained in exchange for new operating lease liabilities		5,534		922
Reduction in operating right-of-use assets due to lease terminations		1,439		—

Maturities of Lease Liabilities

Maturities of lease liabilities were as follows as of March 29, 2020:

	Operating Leases
Remainder of 2020		34,954
2021		44,610
2022		39,071
2023		34,321
2024		31,180
2025		28,836
Thereafter		112,902
Total lease payments		325,874
Less: imputed interest		(93,271	)
Present value of lease liabilities	$	232,603

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 29, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

A summary of stock option activity for the 13 weeks ended March 29, 2020 is as follows:

Options	Shares (Thousands)			Weighted Average Exercise Price		Aggregate Intrinsic Value (Thousands)		Weighted Average Remaining Term (Years)
Outstanding—December 29, 2019		1,774		$	11.34	$	—		4.33
Granted		—			—
Exercised		—			—
Canceled		(33	)		10.51
Outstanding—March 29, 2020		1,741			11.35	$	—		4.01
Exercisable—March 29, 2020		1,563		$	11.12	$	—		3.60

Summary of RSU Activity

A summary of RSU activity for the 13 weeks ended March 29, 2020 is as follows:

RSUs	Number of RSUs (Thousands)			Weighted Average Fair Value per Share
Non-vested as of December 29, 2019		463		$	7.59
Granted		158			3.88
Vested		(68	)		3.18
Canceled		—			—
Non-vested as of March 29, 2020		553		$	6.38

Organization and Other Matters - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 29, 2020 USD ($) Shop Subsidiary JointVenture	Mar. 31, 2019 USD ($)	Mar. 27, 2020 USD ($)	Dec. 30, 2019 USD ($)
Nature Of Business And Basis Of Presentation [Line Items]
Number of shops franchisees operate \| Shop	40
Impairment charge	$ 5,900	$ 0
Income tax expense (benefit)	$ (3,709)	$ 13,619
Tax refund from net operating loss carryback			$ 3,700
Number of wholly owned subsidiaries \| Subsidiary	7
Number of joint ventures \| JointVenture	7
ASU 2016-13 (Topic 326) [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Reduction in accumulated deficit				$ 5
COVID 19 [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Impairment charge	$ 5,900
Income tax expense (benefit)	3,700
Tax refund from net operating loss carryback	3,700
COVID 19 [Member] \| Revolving Credit Facility [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Line of credit facility amount borrowed	$ 40,000
Minimum [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Number of shops Potbelly Corporation owns or operates \| Shop	400
Ownership interest rate	51.00%
Maximum [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Ownership interest rate	80.00%

Revenue - Additional Information (Detail) - USD ($)	3 Months Ended
Revenue - Additional Information (Detail) - USD ($)	Mar. 29, 2020	Mar. 31, 2019
Disaggregation Of Revenue [Line Items]
Amount of revenue recognized	$ 87,590,000	$ 98,087,000
Aggregate value of remaining performance obligation on outstanding contracts	3,248,000
Revenue recognized related to prior periods	0	0
January 1, 2018 Liability Ending Balance [Member]
Disaggregation Of Revenue [Line Items]
Amount of revenue recognized	500,000	800,000
Point in Time Sales [Member]
Disaggregation Of Revenue [Line Items]
Amount of revenue recognized	87,500,000	97,800,000
Over Time Sales [Member]
Disaggregation Of Revenue [Line Items]
Amount of revenue recognized	$ 100,000	$ 300,000

Revenue - Summary of Current and Noncurrent Contract Liabilities from Contracts with Customers (Detail) $ in Thousands	3 Months Ended
	Mar. 29, 2020 USD ($)
Revenue From Contract With Customer [Abstract]
Beginning balance of current contract liability	$ (1,594)
Ending balance of current contract liability	(1,264)
Decrease in contract liability	(330)
Beginning balance of noncurrent contract liability	(2,054)
Ending balance of noncurrent contract liability	(1,984)
Decrease in contract liability	$ (70)

Revenue - Summary of Expected Revenue Recognition Related to Contract Liabilities (Detail1) $ in Thousands	Mar. 29, 2020 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligations	$ 3,248
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligations	$ 942
Revenue, remaining performance obligation, expected timing of satisfaction, period	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligations	$ 302
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligations	$ 240
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligations	$ 206
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligations	$ 174
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligations	$ 1,384
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year

Revenue - Summary of Expected Revenue Recognition Related to Contract Liabilities (Detail) $ in Thousands	Mar. 29, 2020 USD ($)
Revenue From Contract With Customer [Abstract]
Revenue, remaining performance obligations	$ 3,248

Fair Value Measurement - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment charge	$ 5.9	$ 0.0
COVID 19 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment charge	$ 5.9
Impact of the COVID 19 pandamic to thr global economy	Due to the recent impact of the COVID-19 pandemic to the global economy, including but not limited to, the volatility of the Company's stock price as well as that of its competitors, declining sales at the Company's restaurants and the challenging environment for the restaurant industry generally, the Company determined that there were indicators of potential impairment of its goodwill and indefinite-lived intangible assets during the thirteen weeks ended March 29, 2020. As such, the Company performed an impairment assessment for both goodwill and indefinite lived intangible assets and concluded that the fair value of these assets exceeded their carrying values. Accordingly, the Company did not record any impairment to its goodwill or indefinite-lived intangible assets during the thirteen weeks ended March 29, 2020. The ultimate severity and longevity of the COVID-19 pandemic is unknown, and therefore, it is possible that impairments could be identified in future periods, and such amounts could be material.

Loss Per Share - Additional Information (Detail) - shares	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019
Common Share Options [Member]
Loss Per Share [Line Items]
Potential common shares included in diluted shares outstanding	0	0

Loss Per Share - Summary of Loss Per Share Calculation (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019
Loss Per Share [Line Items]
Net loss attributable to Potbelly Corporation	$ (13,336)	$ (18,439)
Weighted average common shares outstanding-basic	23,646	24,133
Weighted average common shares outstanding-diluted	23,646	24,133
Loss per share available to common stockholders-basic	$ (0.56)	$ (0.76)
Loss per share available to common stockholders-diluted	$ (0.56)	$ (0.76)
Common Share Options [Member]
Loss Per Share [Line Items]
Potentially dilutive shares that are considered anti-dilutive	2,294	2,387

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019	Mar. 27, 2020
Income Tax Disclosure [Abstract]
Tax refund from net operating loss carryback			$ 3,700
Income tax expense (benefit)	$ (3,709)	$ 13,619
Deferred tax assets, valuation allowance	$ 13,600

Leases - Operating Lease Term and Discount Rate (Detail)	Mar. 29, 2020	Mar. 31, 2019
Leases [Abstract]
Weighted average remaining lease term (years)	8 years 3 months 29 days	8 years 10 months 24 days
Weighted average discount rate	7.90%	8.01%

Leases - Components of Lease Cost (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019
Lessee Lease Description [Line Items]
Total lease cost	$ 15,092	$ 14,499
Occupancy and General and Administrative Expenses [Member]
Lessee Lease Description [Line Items]
Operating lease cost	11,770	10,995
Occupancy Expenses [Member]
Lessee Lease Description [Line Items]
Variable lease cost	$ 3,322	$ 3,504

Leases - Supplemental Disclosures of Cash Flow Information Related to Leases (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019
Leases [Abstract]
Operating cash flows rent paid for operating lease liabilities	$ 11,979	$ 11,938
Operating right-of-use assets obtained in exchange for new operating lease liabilities	5,534	$ 922
Reduction in operating right-of-use assets due to lease terminations	$ 1,439

Leases - Additional Information (Detail) $ in Millions	Mar. 29, 2020 USD ($)
Leases [Abstract]
Additional operating leases payments related to shops not yet open, amount	$ 0

Leases - Maturities of Lease Liabilities (Detail) $ in Thousands	Mar. 29, 2020 USD ($)
Operating Leases
Remainder of 2020	$ 34,954
2021	44,610
2022	39,071
2023	34,321
2024	31,180
2025	28,836
Thereafter	112,902
Total lease payments	325,874
Less: imputed interest	(93,271)
Present value of lease liabilities	$ 232,603

Debt and Credit Facilities - Additional Information (Detail)		1 Months Ended	3 Months Ended
	Aug. 07, 2019 USD ($)	May 15, 2020 USD ($)	Mar. 29, 2020 USD ($)	Mar. 17, 2020 USD ($)	Mar. 31, 2019 USD ($)
April 30, 2020 [Member]
Short Term Debt [Line Items]
Minimum Liquidity Level			$ 45,000,000
May 31, 2020 [Member]
Short Term Debt [Line Items]
Minimum Liquidity Level			32,500,000
April 2020 [Member]
Short Term Debt [Line Items]
Minimum Building Adjusted EBITDA			(8,500,000)
April 2020 Through May 2020 [Member]
Short Term Debt [Line Items]
Minimum Building Adjusted EBITDA			(16,000,000)
June 30, 2020 [Member]
Short Term Debt [Line Items]
Minimum TTM adjusted EBITDA			$ 16,000,000
June 30, 2020 [Member] \| Minimum [Member]
Short Term Debt [Line Items]
Total debt to adjusted EBITDA ratio			2.25
June 30, 2020 [Member] \| Maximum [Member]
Short Term Debt [Line Items]
Total debt to adjusted EBITDA ratio			1.00
September 30, 2020 [Member]
Short Term Debt [Line Items]
Minimum TTM adjusted EBITDA			$ 15,000,000
September 30, 2021 [Member]
Short Term Debt [Line Items]
Minimum TTM adjusted EBITDA			17,000,000
Credit Agreement Amendment [Member]
Short Term Debt [Line Items]
Upfront fee		1.00%
London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member]
Short Term Debt [Line Items]
Credit facility agreement, interest rate	1.75%
London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member] \| Credit Agreement Amendment [Member]
Short Term Debt [Line Items]
Credit facility agreement, interest rate		5.00%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member]
Short Term Debt [Line Items]
Credit facility agreement, interest rate	1.25%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member] \| Credit Agreement Amendment [Member]
Short Term Debt [Line Items]
Credit facility agreement, interest rate		1.00%
JPMorgan Chase Bank, N.A. [Member]
Short Term Debt [Line Items]
Commitment fee, percentage	0.20%
JPMorgan Chase Bank, N.A. [Member] \| Credit Agreement Amendment [Member]
Short Term Debt [Line Items]
Credit facility agreement, future increases		$ 20,000,000
Commitment fee, percentage		1.00%
Credit facility agreement, amount outstanding		$ 15,000,000
Line of credit facility amount borrowed		$ 28,000,000
JPMorgan Chase Bank, N.A. [Member] \| COVID 19 [Member]
Short Term Debt [Line Items]
Credit facility agreement, amount outstanding			39,800,000		$ 0
JPMorgan Chase Bank, N.A. [Member] \| Maximum [Member] \| Credit Agreement Amendment [Member]
Short Term Debt [Line Items]
Credit facility agreement, Maturity date		Mar. 31, 2022
JPMorgan Chase Bank, N.A. [Member] \| Minimum [Member] \| Credit Agreement Amendment [Member]
Short Term Debt [Line Items]
Credit facility agreement, Maturity date		Jul. 31, 2022
JPMorgan Chase Bank, N.A. [Member] \| Prime Rate [Member] \| Maximum [Member]
Short Term Debt [Line Items]
Credit facility agreement, interest rate	0.50%
JPMorgan Chase Bank, N.A. [Member] \| Prime Rate [Member] \| Minimum [Member]
Short Term Debt [Line Items]
Credit facility agreement, interest rate	0.00%
JPMorgan Chase Bank, N.A. [Member] \| Prime Rate [Member] \| Minimum [Member] \| Credit Agreement Amendment [Member]
Short Term Debt [Line Items]
Credit facility agreement, interest rate		4.00%
Revolving Credit Facility [Member] \| COVID 19 [Member]
Short Term Debt [Line Items]
Line of credit facility amount borrowed			$ 40,000,000
Revolving Credit Facility [Member] \| JPMorgan Chase Bank, N.A. [Member]
Short Term Debt [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]
Short Term Debt [Line Items]
Line of credit facility amount borrowed		$ 15,000,000
Revolving Credit Facility [Member] \| JPMorgan Chase Bank, N.A. [Member] \| COVID 19 [Member]
Short Term Debt [Line Items]
Line of credit facility amount borrowed				$ 39,800,000
Revolving Credit Facility [Member] \| JPMorgan Chase Bank, N.A. [Member] \| Maximum [Member]
Short Term Debt [Line Items]
Credit facility agreement, future increases	$ 20,000,000

Capital Stock - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019	May 08, 2018
Equity Class Of Treasury Stock [Line Items]
Stock repurchase program, authorized amount			$ 65,000,000
Common stock repurchased value		$ 1,144,000
Stock Repurchase Program [Member]
Equity Class Of Treasury Stock [Line Items]
Common stock shares repurchased	0	135,000
Common stock repurchased value		$ 1,100,000

Stock-Based Compensation - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended
	Mar. 31, 2019	Mar. 29, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized stock-based compensation expense		$ 490,000	$ 459,000
Stock units issued		158,000
Stock units issued, grant-date fair value		$ 3.88
Stock-based compensation expense		$ 490,000	459,000
Common Share Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized stock-based compensation expense		200,000	300,000
Unrecognized stock compensation expense		$ 600,000
Unrecognized stock compensation expense, recognition period		2022
Stock-based compensation expense		$ 200,000	300,000
Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized stock-based compensation expense		$ 0	0
Vesting description		The PSUs will vest fully on the third anniversary of the grant date. The quantity of shares that will vest ranges from 0% to 200% of the targeted number of shares. If the defined minimum targets are not met, then no shares will vest.
Stock units issued	188,414
Stock units issued, grant-date fair value	$ 8.46
Stock-based compensation expense		$ 0	0
Performance Stock Units [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage of targeted number of shares	0.00%
Performance Stock Units [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage of targeted number of shares	200.00%
Employee and Non Employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants vesting period		4 years
Method used to determine fair value of the options		Black-Scholes option pricing model
Stock options granted		0
Non-Employee Board Of Directors [Member] \| Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants vesting period		3 years
Recognized stock-based compensation expense		$ 200,000	300,000
Unrecognized stock compensation expense		$ 1,900,000
Unrecognized stock compensation expense, recognition period		2023
Vesting description		The employee grants vest in one-third increments over a three-year period.
Stock-based compensation expense		$ 200,000	$ 300,000
Non-Employee Board Of Directors [Member] \| Restricted Stock Units (RSUs) [Member] \| First Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		50.00%
Non-Employee Board Of Directors [Member] \| Restricted Stock Units (RSUs) [Member] \| Second Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		50.00%

Stock-Based Compensation - Summary of Stock Option Activity (Detail) - $ / shares shares in Thousands	3 Months Ended	12 Months Ended
	Mar. 29, 2020	Dec. 29, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding shares, beginning balance	1,774
Options, canceled	(33)
Options outstanding shares, ending balance	1,741	1,774
Options outstanding shares, exercisable	1,563
Options outstanding weighted average exercise price, beginning balance	$ 11.34
Options, weighted average exercise price, canceled	10.51
Options outstanding weighted average exercise price, ending balance	11.35	$ 11.34
Options outstanding weighted average exercise price, exercisable	$ 11.12
Option outstanding weighted average remaining term	4 years 3 days	4 years 3 months 29 days
Options exercisable weighted average remaining term	3 years 7 months 6 days

Stock-Based Compensation - Summary of RSU Activity (Detail) shares in Thousands	3 Months Ended
	Mar. 29, 2020 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of RSUs, Non-vested, beginning balance \| shares	463
Number of RSUs, Granted \| shares	158
Number of RSUs, Vested \| shares	(68)
Number of RSUs, Non-vested, ending balance \| shares	553
Weighted Average Fair Value per Share, Non-vested, beginning balance \| $ / shares	$ 7.59
Weighted Average Fair Value per Share, Granted \| $ / shares	3.88
Weighted Average Fair Value per Share, Vested \| $ / shares	3.18
Weighted Average Fair Value per Share, Non-vested, ending balance \| $ / shares	$ 6.38

Commitment and Contingencies - Additional Information (Detail)	1 Months Ended	3 Months Ended
	Oct. 31, 2017	Mar. 29, 2020
Commitments And Contingencies Disclosure [Abstract]
Purported collective and class action lawsuit filed date	October 2017
Settlement agreement date		February 4, 2020

Subsequent Events - Additional Information (Detail) - Potbelly Sandwich Works, LLC [Member] - Subsequent Event [Member] - CARES Act Of 2020 [Member] - JPMorgan Chase Bank, N.A. [Member] - Loan [Member] - USD ($)	Apr. 28, 2020	Apr. 10, 2020
Subsequent Event [Line Items]
Loan amount		$ 10,000,000
Repayments of proceeds from the loan	$ 10,000,000