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Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2019	Jul. 28, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Trading Symbol	PBPB
Entity Registrant Name	Potbelly Corporation
Entity Central Index Key	0001195734
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-29
Entity Filer Category	Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		23,768,375
Entity File Number	001-36104
Entity Tax Identification Number	364466837
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	Illinois
Entity Address, Postal Zip Code	60606
City Area Code	312
Local Phone Number	951-0600

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 30, 2018
Current assets
Cash and cash equivalents	$ 18,066	$ 19,775
Accounts receivable, net of allowances of $131 and $113 as of June 30, 2019 and December 30, 2018, respectively	4,545	4,737
Inventories	3,357	3,482
Prepaid expenses and other current assets	8,182	11,426
Total current assets	34,150	39,420
Property and equipment, net	81,628	87,782
Right-of-use assets for operating leases	216,540
Indefinite-lived intangible assets	3,404	3,404
Goodwill	2,222	2,222
Deferred income taxes		13,385
Deferred expenses, net and other assets	6,898	7,002
Total assets	344,842	153,215
Current liabilities
Accounts payable	4,222	3,835
Accrued expenses	21,303	25,029
Short-term operating lease liabilities	29,126
Accrued income taxes	162	162
Total current liabilities	54,813	29,026
Deferred rent and landlord allowances		22,905
Long-term operating lease liabilities	210,898
Other long-term liabilities	6,255	5,751
Total liabilities	271,966	57,682
Commitments and contingencies (Note 9)
Equity
Common stock, $0.01 par value—authorized 200,000,000 shares; outstanding 23,768,375 and 24,142,586 shares as of June 30, 2019 and December 30, 2018, respectively	331	330
Additional paid-in-capital	434,407	432,771
Treasury stock, held at cost, 9,291,732 and 8,801,154 shares as of June 30, 2019, and December 30, 2018, respectively	(111,874)	(108,372)
Accumulated deficit	(250,394)	(229,558)
Total stockholders’ equity	72,470	95,171
Non-controlling interest	406	362
Total equity	72,876	95,533
Total liabilities and equity	$ 344,842	$ 153,215

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 30, 2018
Statement Of Financial Position [Abstract]
Allowances on accounts receivable	$ 131	$ 113
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized	200,000,000	200,000,000
Common stock, outstanding	23,768,375	24,142,586
Treasury stock, shares	9,291,732	8,801,154

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Revenues
Total revenues	$ 105,630	$ 110,347	$ 203,717	$ 213,264
Sandwich shop operating expenses
Cost of goods sold, excluding depreciation	28,264	28,639	54,242	55,275
Labor and related expenses	32,114	32,412	64,087	63,991
Occupancy expenses	15,230	14,985	29,607	29,711
Other operating expenses	11,816	12,793	23,961	25,293
General and administrative expenses	13,843	13,440	26,552	25,628
Depreciation expense	5,585	5,858	11,121	11,684
Pre-opening costs		68	10	136
Impairment and loss on disposal of property and equipment	246	2,057	328	4,081
Total expenses	107,098	110,252	209,908	215,799
Income (loss) from operations	(1,468)	95	(6,191)	(2,535)
Interest expense	35	28	67	55
Income (loss) before income taxes	(1,503)	67	(6,258)	(2,590)
Income tax expense (benefit)	246	302	13,865	(202)
Net loss	(1,749)	(235)	(20,123)	(2,388)
Net income attributable to non-controlling interest	117	125	182	166
Net loss attributable to Potbelly Corporation	$ (1,866)	$ (360)	$ (20,305)	$ (2,554)
Net loss per common share attributable to common stockholders:
Basic	$ (0.08)	$ (0.01)	$ (0.85)	$ (0.10)
Diluted	$ (0.08)	$ (0.01)	$ (0.85)	$ (0.10)
Weighted average shares outstanding:
Basic	23,908,095	25,551,386	24,020,567	25,348,121
Diluted	23,908,095	25,551,386	24,020,567	25,348,121
Product [Member]
Revenues
Total revenues	$ 104,801	$ 109,381	$ 202,059	$ 211,628
Franchise Royalties And Fees [Member]
Revenues
Total revenues	$ 829	$ 966	$ 1,658	$ 1,636

Condensed Consolidated Statements of Equity (Unaudited) - USD ($) $ 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. 31, 2017	$ 117,238	$ 318	$ (85,262)	$ 421,657	$ (219,990)	$ 515
Beginning balance, common shares at Dec. 31, 2017		24,999,688
Cumulative impact \| ASU 2014-09 (Topic 606) [Member]	(690)				(690)
Net income (loss)	(2,388)				(2,554)	166
Stock-based compensation plans	6,744	$ 9		6,735
Stock-based compensation plans, shares		925,375
Repurchases of common stock	(3,449)		(3,449)
Repurchases of common stock, shares		(264,339)
Distributions to non-controlling interest	(256)					(256)
Treasury shares used for stock-based plans	(116)		(116)
Treasury shares used for stock-based plans, shares		(8,771)
Stock-based compensation expense	2,251			2,251
Ending balance at Jul. 01, 2018	119,334	$ 327	(88,827)	430,643	(223,234)	425
Ending balance, common shares at Jul. 01, 2018		25,651,953
Beginning balance at Apr. 01, 2018	117,333	$ 321	(85,441)	424,771	(222,874)	556
Beginning balance, common shares at Apr. 01, 2018		25,286,229
Net income (loss)	(235)				(360)	125
Stock-based compensation plans	4,489	$ 6		4,483
Stock-based compensation plans, shares		625,063
Repurchases of common stock	(3,386)		(3,386)
Repurchases of common stock, shares		(259,339)
Distributions to non-controlling interest	(256)					(256)
Stock-based compensation expense	1,389			1,389
Ending balance at Jul. 01, 2018	119,334	$ 327	(88,827)	430,643	(223,234)	425
Ending balance, common shares at Jul. 01, 2018		25,651,953
Beginning balance at Dec. 30, 2018	$ 95,533	$ 330	(108,372)	432,771	(229,558)	362
Beginning balance, common shares at Dec. 30, 2018	24,142,586	24,142,586
Cumulative impact \| ASU 2016-02 (Topic 842) [Member]	$ (531)				(531)
Net income (loss)	(20,123)				(20,305)	182
Stock-based compensation plans	173	$ 1		172
Stock-based compensation plans, shares		116,367
Repurchases of common stock	(3,467)		(3,467)
Repurchases of common stock, shares		(485,659)
Distributions to non-controlling interest	(177)					(177)
Contributions from non-controlling interest	39					39
Treasury shares used for stock-based plans	(35)		(35)
Treasury shares used for stock-based plans, shares		(4,919)
Stock-based compensation expense	1,464			1,464
Ending balance at Jun. 30, 2019	$ 72,876	$ 331	(111,874)	434,407	(250,394)	406
Ending balance, common shares at Jun. 30, 2019	23,768,375	23,768,375
Beginning balance at Mar. 31, 2019	$ 76,088	$ 330	(109,541)	433,400	(248,528)	427
Beginning balance, common shares at Mar. 31, 2019		24,038,211
Net income (loss)	(1,749)				(1,866)	117
Stock-based compensation plans	3	$ 1		2
Stock-based compensation plans, shares		82,694
Repurchases of common stock	(2,323)		(2,323)
Repurchases of common stock, shares		(350,659)
Distributions to non-controlling interest	(177)					(177)
Contributions from non-controlling interest	39					39
Treasury shares used for stock-based plans	(10)		(10)
Treasury shares used for stock-based plans, shares		(1,871)
Stock-based compensation expense	1,005			1,005
Ending balance at Jun. 30, 2019	$ 72,876	$ 331	$ (111,874)	$ 434,407	$ (250,394)	$ 406
Ending balance, common shares at Jun. 30, 2019	23,768,375	23,768,375

Condensed Consolidated Statements of Equity (Unaudited) (Parenthetical) $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($)
ASU 2016-02 (Topic 842) [Member]
Cumulative impact tax	$ 196

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018
Cash flows from operating activities:
Net income (loss)	$ (20,123)	$ (2,388)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation expense	11,121	11,684
Noncash lease expense	13,826
Deferred income tax	13,790	(150)
Stock-based compensation expense	1,464	2,251
Asset impairment, store closure and disposal of property and equipment	433	4,221
Other operating activities	18	311
Changes in operating assets and liabilities:
Accounts receivable, net	192	(822)
Inventories	125	263
Prepaid expenses and other assets	3,322	(924)
Accounts payable	303	676
Operating lease liabilities	(15,281)
Accrued expenses and other liabilities	(2,202)	2,745
Net cash provided by operating activities:	6,988	17,867
Cash flows from investing activities:
Purchases of property and equipment	(5,230)	(11,614)
Net cash used in investing activities:	(5,230)	(11,614)
Cash flows from financing activities:
Proceeds from exercise of stock options	173	6,744
Employee taxes on certain stock-based payment arrangements	(35)	(512)
Treasury stock repurchases	(3,467)	(3,449)
Distributions to non-controlling interest	(177)	(256)
Contributions from non-controlling interest	39
Net cash (used in) provided by financing activities:	(3,467)	2,527
Net increase (decrease) in cash and cash equivalents	(1,709)	8,780
Cash and cash equivalents at beginning of period	19,775	25,530
Cash and cash equivalents at end of period	18,066	34,310
Supplemental cash flow information:
Income taxes paid	180	244
Interest paid	48	38
Supplemental non-cash investing and financing activities:
Unpaid liability for purchases of property and equipment	$ 583	$ 1,299

Organization and Other Matters

6 Months Ended

Jun. 30, 2019

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 more than 40 shops domestically.

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 30, 2018. 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 financial position as of June 30, 2019 and December 30, 2018, its statement of operations for the 13 and 26 weeks ended June 30, 2019 and July 1, 2018, the statement of equity for the 13 and 26 weeks ended June 30, 2019 and July 1, 2018 and its statement of cash flows for the 26 weeks ended June 30, 2019 and July 1, 2018 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.

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 2019 and 2018 both consist of 52 weeks. The fiscal quarters ended June 30, 2019 and July 1, 2018 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 31, 2018, the Company adopted ASU 2016-02, “Leases (Topic 842),” along with related clarifications and improvements. This pronouncement requires lessees to recognize a liability for lease obligations, which represents the discounted obligation to make future lease payments, and a corresponding right-of-use asset on the balance sheet. The guidance requires disclosure of key information about leasing arrangements that is intended to give financial statement users the ability to assess the amount, timing, and potential uncertainty of cash flows related to leases. We elected the optional transition method to apply the standard as of the effective date and therefore, prior period amounts have not been adjusted and continue to be reported in accordance with our historical accounting under previous lease guidance, ASC Topic 840: Leases (Topic 840). The adoption of Topic 842 had a material impact on the consolidated balance sheets and an immaterial impact on the consolidated statements of operations, consolidated statements of equity and consolidated statements of cash flows.

Our practical expedients were as follows:

	Implications as of December 31, 2018
Practical expedient package	We have not reassessed whether any expired or existing contracts are, or contain, leases.
	We have not reassessed the lease classification for any expired or existing leases.
	We have not reassessed initial direct costs for any expired or existing leases.
Hindsight practical expedient	We have not elected the hindsight practical expedient, which permits the use of hindsight when determining lease term and impairment of operating lease assets.

The impact on the consolidated balance sheet is as follows:

				Adjustments Due
	December 30,			to the Adoption of			December 31,
	2018			Topic 842			2018
Assets
Current assets
Cash and cash equivalents	$	19,775		$	—		$	19,775
Accounts receivable, net of allowances of $113 as of December 30, 2018		4,737			—			4,737
Inventories		3,482			—			3,482
Prepaid expenses and other current assets		11,426			—			11,426
Total current assets		39,420			—			39,420

Property and equipment, net		87,782			—			87,782
Right-of-use assets for operating leases		—			232,477			232,477
Indefinite-lived intangible assets		3,404			—			3,404
Goodwill		2,222			—			2,222
Deferred income taxes, noncurrent		13,385			195			13,580
Deferred expenses, net and other assets		7,002			—			7,002
Total assets	$	153,215		$	232,672		$	385,887

Liabilities and Equity
Current liabilities
Accounts payable	$	3,835		$	—		$	3,835
Accrued expenses⁽¹⁾		25,029			(1,124	)		23,905
Short-term operating lease liabilities		—			28,826			28,826
Accrued income taxes		162			—			162
Total current liabilities		29,026			27,702			56,728

Deferred rent and landlord allowances⁽¹⁾		22,905			(22,905	)		—
Long-term operating lease liabilities		—			228,406			228,406
Other long-term liabilities		5,751			—			5,751
Total liabilities		57,682			233,203			290,885

Stockholders’ equity
Common stock, $0.01 par value—authorized 200,000,000 shares; outstanding 24,142,586 shares as of December 30, 2018		330			—			330
Additional paid-in-capital		432,771			—			432,771
Treasury stock, held at cost, 8,801,154 shares as of December 30, 2018		(108,372	)		—			(108,372	)
Accumulated deficit⁽²⁾		(229,558	)		(531	)		(230,089	)
Total stockholders’ equity		95,171			(531	)		94,640
Non-controlling interest		362			—			362
Total stockholders' equity		95,533			(531	)		95,002

Total liabilities and equity	$	153,215		$	232,672		$	385,887

(1)	Adjustment to reclassify deferred rent and tenant improvement allowance to right-of-use assets for operating leases upon the adoption of Topic 842.

(2)	The Company recorded a net reduction of $0.5 million to opening accumulated deficit as of December 31, 2018, due to the cumulative impact of adopting Topic 842.

Revenue

6 Months Ended

Jun. 30, 2019

Revenue From Contract With Customer [Abstract]

Revenue

(2) Revenue

Potbelly primarily earns revenue at a point in time through sales at our sandwich shop locations and records such revenue 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 and 26 weeks ended June 30, 2019, revenue recognized from all revenue sources on point in time sales was $105.5 million and $203.3 million, respectively, and revenue recognized from sales over time was $0.1 million and $0.4 million, respectively. For the 13 and 26 weeks ended July 1, 2018, revenue recognized from all revenue sources on point in time sales was $110.2 million and $212.9 million, respectively, and revenue recognized from sales over time was $0.2 million and $0.4 million, respectively.

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 31, 2018	$	(2,184	)	$	(1,631	)
Ending balance as of June 30, 2019		(1,687	)		(1,960	)
Increase (decrease) in contract liability	$	(497	)	$	329

The aggregate value of remaining performance obligations on outstanding contracts was $3.6 million as of June 30, 2019. 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
2019	$	1,250
2020		288
2021		246
2022		199
2023		192
Thereafter		1,472
Total revenue recognized	$	3,647

For the 13 and 26 weeks ended June 30, 2019, the amount of revenue recognized related to the December 31, 2018 liability ending balance was $0.6 million and $1.5 million, respectively. For the 13 and 26 weeks ended July 1, 2018, the amount of revenue recognized related to the January 1, 2018 liability ending balance was $0.6 million and $1.6 million, respectively. This revenue related to the recognition of gift card redemptions and upfront franchise fees. For the 26 weeks ended June 30, 2019 and the 26 weeks ended July 1, 2018, the Company did not recognize any revenue from obligations satisfied (or partially satisfied) in prior periods.

Fair Value Measurement

6 Months Ended

Jun. 30, 2019

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. At transition of adoption to ASC 842, the Company impaired $0.7 million of pre-tax right-of-use assets related to previously impaired shops. This amount is recorded, net of tax, as an opening reduction to retained earnings. After performing a periodic review of the Company’s shops during the 13 and 26 weeks ended June 30, 2019, 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 $0.2 million for the 13 and 26 weeks ended June 30, 2019. The Company recorded an impairment charge of $2.1 million and $4.1 million for the 13 and 26 weeks ended July 1, 2018, respectively.

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.

- 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

6 Months Ended

Jun. 30, 2019

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 and 26 weeks ended June 30, 2019, and July 1, 2018, 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						For the 26 Weeks Ended
	June 30,			July 1,			June 30,			July 1,
	2019			2018			2019			2018
Net loss attributable to Potbelly Corporation	$	(1,866	)	$	(360	)	$	(20,305	)	$	(2,554	)
Weighted average common shares outstanding-basic		23,908,095			25,551,386			24,020,567			25,348,121
Plus: Effect of potential stock options exercise		—			—			—			—
Weighted average common shares outstanding-diluted		23,908,095			25,551,386			24,020,567			25,348,121
Loss per share available to common stockholders-basic	$	(0.08	)	$	(0.01	)	$	(0.85	)	$	(0.10	)
Loss per share available to common stockholders-diluted	$	(0.08	)	$	(0.01	)	$	(0.85	)	$	(0.10	)
Potentially dilutive shares that are considered anti-dilutive:
Common share options		2,376,713			2,557,475			2,381,767			2,829,461

Income Taxes

6 Months Ended

Jun. 30, 2019

Income Tax Disclosure [Abstract]

Income Taxes

(5) Income Taxes

Our interim tax provision is determined using an estimated annual effective tax rate and adjusted for discrete taxable events that occur during the quarter. The difference between the effective tax rate in 2019 and 2018 is the recording of the valuation allowance in the first quarter of 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 considered recent financial operating results, the change in projected future taxable income for fiscal year 2019, the reversal of existing taxable temporary differences, and tax planning strategies. As a result of the changes in projected taxable income for 2019, the Company estimates it will be in a cumulative loss position as of December 29, 2019. Therefore, the Company determined that the negative evidence outweighed the positive evidence and, therefore, 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 continues to record a valuation allowance against all of our deferred tax assets as of June 30, 2019. The Company did not provide for an income tax benefit on the pre-tax loss recorded for the three and six months ended June 30, 2019. This accounting treatment has no effect on the Company’s ability to utilize deferred tax assets to reduce future cash tax payments. The Company will continue to assess the likelihood of the realization of its deferred tax assets at the end of each reporting period and the valuation allowance will be adjusted accordingly.

Leases

6 Months Ended

Jun. 30, 2019

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. As we have no outstanding debt nor committed credit facilities, secured or otherwise, we estimate 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.

Related to the adoption of Topic 842, our policy elections were as follows:

Separation of lease and non-lease components		We elected this expedient to account for lease and non-lease components as a single component for our entire population of operating lease assets.
Short-term policy		We have elected the short-term lease recognition exemption for all applicable classes of underlying assets. Short-term disclosures include only those leases with a term greater than one month and 12 months or less, and expense is recognized on a straight-line basis over the lease term. Leases with an initial term of 12 months or less, that do not include an option to purchase the underlying asset that we are reasonably certain to exercise, are not recorded on the balance sheet.

Supplemental balance sheet information related to leases was as follows:

		June 30,
Operating Leases	Classification	2019
Right-of-use assets	Right-of-use assets for operating leases	$	216,540
Short-term lease liabilities	Short-term operating lease liabilities		29,126
Long-term lease liabilities	Long-term operating lease liabilities		210,898
Total lease liabilities			240,024

Operating lease term and discount rate were as follows:

	June 30,
	2019
Weighted average remaining lease term (years)	8.72
Weighted average discount rate		8.03	%

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		26 weeks ending
		June 30,		June 30,
	Classification	2019		2019
Operating lease cost	Occupancy and General and administrative expenses		11,611		22,606
Variable lease cost	Occupancy		3,649		7,153
Total lease cost		$	15,260	$	29,759

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

	13 weeks ending			26 weeks ending
	June 30,			June 30,
	2019			2019
Operating cash flows rent paid for operating lease liabilities		11,788			23,726
Operating right-of-use assets obtained in exchange for new operating lease liabilities		2,735			3,657
Reduction in operating right-of-use assets due to lease terminations		(1,320	)		(5,847	)

As of June 30, 2019, the Company has additional operating lease payments related to shops not yet open of $4.4 million. These operating leases will commence during the next fiscal year with an average lease term of 12 years.

Maturities of lease liabilities were as follows as of June 30, 2019:

	Operating Leases
Remainder of 2019		23,542
2020		45,919
2021		41,664
2022		36,359
2023		31,492
2024		28,775
Thereafter		135,169
Total lease payments		342,920
Less: imputed interest		(102,896	)
Present value of lease liabilities	$	240,024

As previously disclosed in our 2018 Annual Report on Form 10-K and under the previous lease accounting, maturities of lease liabilities were as follows as of December 30, 2018:

	Operating Leases
2019		47,918
2020		45,828
2021		41,497
2022		36,120
2023		31,060
Thereafter		138,928
Total minimum lease payments		341,351

Capital Stock

6 Months Ended

Jun. 30, 2019

Equity [Abstract]

Capital Stock

(7) 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 June 30, 2019, the Company repurchased 350,659 shares of its common stock for approximately $2.3 million under the stock repurchase program, including cost and commission, in open market transactions. For the 26 weeks ended June 30, 2019, the Company repurchased 485,659 shares of its common stock for approximately $3.5 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

6 Months Ended

Jun. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

(8) Stock-Based Compensation

Stock options

On May 16, 2019, the Company’s stockholders approved the Potbelly Corporation 2019 Long-Term Incentive Plan (the “2019 Plan”) and, in connection therewith, all equity awards made after that date were made under the 2019 Plan. On June 10, 2019, the Company registered 1,200,000 shares of its common stock reserved for issuance under the 2019 Plan. All remaining shares of common stock reserved for issuance under the previous Amended and Restated 2013 Long-Term Incentive Plan (the “2013 Plan”) are available for issuance under the 2019 Plan and no future awards will be made under the 2013 Plan. 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 and 26 weeks ended June 30, 2019.

A summary of stock option activity for the 26 weeks ended June 30, 2019 is as follows:

Options	Shares (Thousands)			Weighted Average Exercise Price		Aggregate Intrinsic Value (Thousands)		Weighted Average Remaining Term (Years)
Outstanding—December 30, 2018		2,150		$	11.49	$	378		5.13
Granted		—			—
Exercised		(22	)		7.93
Canceled		(198	)		13.54
Outstanding—June 30, 2019		1,930		$	11.32	$	—		5.04
Exercisable—June 30, 2019		1,534		$	11.05	$	—		4.15

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 and 26 weeks ended June 30, 2019, the Company recognized stock-based compensation expense related to stock options of $0.3 million and $0.6 million, respectively. For the 13 weeks and 26 weeks ended July 1, 2018, the Company recognized stock-based compensation expense related to stock options of $0.3 million and $1.0 million, respectively. As of June 30, 2019, unrecognized stock-based compensation expense for stock options was $1.4 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 and 26 weeks ended June 30, 2019, the Company recognized stock-based compensation expense related to RSUs of $0.7 million and $0.9 million, respectively. For the 13 weeks and 26 weeks ended July 1, 2018, the Company recognized stock-based compensation expense related to RSUs of $1.1 million and $1.3 million, respectively. As of June 30, 2019, unrecognized stock-based compensation expense for RSUs was $2.1 million, which will be recognized though fiscal year 2022.

A summary of RSU activity for the 26 weeks ended June 30, 2019 is as follows:

RSUs	Number of RSUs			Weighted Average Fair Value per Share
Non-vested as of December 30, 2018		247		$	11.99
Granted		306			7.02
Vested		(93	)		6.13
Canceled		(13	)		8.46
Non-vested as of June 30, 2019		447		$	8.68

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 of 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 and 26 weeks ended June 30, 2019, the expense associated with the PSUs was not material.

Commitments and Contingencies

6 Months Ended

Jun. 30, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

(9) 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, subject to court approval. All charges related to the claims are reflected in the statement of operations.

Subsequent Event

6 Months Ended

Jun. 30, 2019

Subsequent Events [Abstract]

Subsequent Event

(10) Subsequent Event

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. that expires in July 2022. The Credit Agreement amended and restated 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 Chase Bank, N.A. 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 Chase 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.

Organization and Other Matters (Policies)

6 Months Ended

Jun. 30, 2019

Accounting Policies [Abstract]

Business

Basis of Presentation

Principles of Consolidation

Fiscal Year

Use of Estimates

Recent Accounting Pronouncements

Our practical expedients were as follows:

	Implications as of December 31, 2018
Practical expedient package	We have not reassessed whether any expired or existing contracts are, or contain, leases.
	We have not reassessed the lease classification for any expired or existing leases.
	We have not reassessed initial direct costs for any expired or existing leases.
Hindsight practical expedient	We have not elected the hindsight practical expedient, which permits the use of hindsight when determining lease term and impairment of operating lease assets.

The impact on the consolidated balance sheet is as follows:

				Adjustments Due
	December 30,			to the Adoption of			December 31,
	2018			Topic 842			2018
Assets
Current assets
Cash and cash equivalents	$	19,775		$	—		$	19,775
Accounts receivable, net of allowances of $113 as of December 30, 2018		4,737			—			4,737
Inventories		3,482			—			3,482
Prepaid expenses and other current assets		11,426			—			11,426
Total current assets		39,420			—			39,420

Property and equipment, net		87,782			—			87,782
Right-of-use assets for operating leases		—			232,477			232,477
Indefinite-lived intangible assets		3,404			—			3,404
Goodwill		2,222			—			2,222
Deferred income taxes, noncurrent		13,385			195			13,580
Deferred expenses, net and other assets		7,002			—			7,002
Total assets	$	153,215		$	232,672		$	385,887

Liabilities and Equity
Current liabilities
Accounts payable	$	3,835		$	—		$	3,835
Accrued expenses⁽¹⁾		25,029			(1,124	)		23,905
Short-term operating lease liabilities		—			28,826			28,826
Accrued income taxes		162			—			162
Total current liabilities		29,026			27,702			56,728

Deferred rent and landlord allowances⁽¹⁾		22,905			(22,905	)		—
Long-term operating lease liabilities		—			228,406			228,406
Other long-term liabilities		5,751			—			5,751
Total liabilities		57,682			233,203			290,885

Stockholders’ equity
Common stock, $0.01 par value—authorized 200,000,000 shares; outstanding 24,142,586 shares as of December 30, 2018		330			—			330
Additional paid-in-capital		432,771			—			432,771
Treasury stock, held at cost, 8,801,154 shares as of December 30, 2018		(108,372	)		—			(108,372	)
Accumulated deficit⁽²⁾		(229,558	)		(531	)		(230,089	)
Total stockholders’ equity		95,171			(531	)		94,640
Non-controlling interest		362			—			362
Total stockholders' equity		95,533			(531	)		95,002

Total liabilities and equity	$	153,215		$	232,672		$	385,887

(1)	Adjustment to reclassify deferred rent and tenant improvement allowance to right-of-use assets for operating leases upon the adoption of Topic 842.

(2)	The Company recorded a net reduction of $0.5 million to opening accumulated deficit as of December 31, 2018, due to the cumulative impact of adopting Topic 842.

Organization and Other Matters (Tables)

6 Months Ended

Jun. 30, 2019

ASU 2016-02 (Topic 842) [Member]

New Accounting Pronouncements Or Change In Accounting Principle [Line Items]

Schedule of Impact on Consolidated Balance Sheet

The impact on the consolidated balance sheet is as follows:

				Adjustments Due
	December 30,			to the Adoption of			December 31,
	2018			Topic 842			2018
Assets
Current assets
Cash and cash equivalents	$	19,775		$	—		$	19,775
Accounts receivable, net of allowances of $113 as of December 30, 2018		4,737			—			4,737
Inventories		3,482			—			3,482
Prepaid expenses and other current assets		11,426			—			11,426
Total current assets		39,420			—			39,420

Property and equipment, net		87,782			—			87,782
Right-of-use assets for operating leases		—			232,477			232,477
Indefinite-lived intangible assets		3,404			—			3,404
Goodwill		2,222			—			2,222
Deferred income taxes, noncurrent		13,385			195			13,580
Deferred expenses, net and other assets		7,002			—			7,002
Total assets	$	153,215		$	232,672		$	385,887

Liabilities and Equity
Current liabilities
Accounts payable	$	3,835		$	—		$	3,835
Accrued expenses⁽¹⁾		25,029			(1,124	)		23,905
Short-term operating lease liabilities		—			28,826			28,826
Accrued income taxes		162			—			162
Total current liabilities		29,026			27,702			56,728

Deferred rent and landlord allowances⁽¹⁾		22,905			(22,905	)		—
Long-term operating lease liabilities		—			228,406			228,406
Other long-term liabilities		5,751			—			5,751
Total liabilities		57,682			233,203			290,885

Stockholders’ equity
Common stock, $0.01 par value—authorized 200,000,000 shares; outstanding 24,142,586 shares as of December 30, 2018		330			—			330
Additional paid-in-capital		432,771			—			432,771
Treasury stock, held at cost, 8,801,154 shares as of December 30, 2018		(108,372	)		—			(108,372	)
Accumulated deficit⁽²⁾		(229,558	)		(531	)		(230,089	)
Total stockholders’ equity		95,171			(531	)		94,640
Non-controlling interest		362			—			362
Total stockholders' equity		95,533			(531	)		95,002

Total liabilities and equity	$	153,215		$	232,672		$	385,887

Revenue (Tables)

6 Months Ended

Jun. 30, 2019

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 31, 2018	$	(2,184	)	$	(1,631	)
Ending balance as of June 30, 2019		(1,687	)		(1,960	)
Increase (decrease) in contract liability	$	(497	)	$	329

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
2019	$	1,250
2020		288
2021		246
2022		199
2023		192
Thereafter		1,472
Total revenue recognized	$	3,647

Loss Per Share (Tables)

6 Months Ended

Jun. 30, 2019

Earnings Per Share [Abstract]

Summary of Loss Per Share Calculation

The following table summarizes the loss per share calculation:

	For the 13 Weeks Ended						For the 26 Weeks Ended
	June 30,			July 1,			June 30,			July 1,
	2019			2018			2019			2018
Net loss attributable to Potbelly Corporation	$	(1,866	)	$	(360	)	$	(20,305	)	$	(2,554	)
Weighted average common shares outstanding-basic		23,908,095			25,551,386			24,020,567			25,348,121
Plus: Effect of potential stock options exercise		—			—			—			—
Weighted average common shares outstanding-diluted		23,908,095			25,551,386			24,020,567			25,348,121
Loss per share available to common stockholders-basic	$	(0.08	)	$	(0.01	)	$	(0.85	)	$	(0.10	)
Loss per share available to common stockholders-diluted	$	(0.08	)	$	(0.01	)	$	(0.85	)	$	(0.10	)
Potentially dilutive shares that are considered anti-dilutive:
Common share options		2,376,713			2,557,475			2,381,767			2,829,461

Leases (Tables)

6 Months Ended

Jun. 30, 2019

Leases [Abstract]

Supplemental Balance Sheet Information Related to Leases

Supplemental balance sheet information related to leases was as follows:

		June 30,
Operating Leases	Classification	2019
Right-of-use assets	Right-of-use assets for operating leases	$	216,540
Short-term lease liabilities	Short-term operating lease liabilities		29,126
Long-term lease liabilities	Long-term operating lease liabilities		210,898
Total lease liabilities			240,024

Operating Lease Term and Discount Rate

Operating lease term and discount rate were as follows:

	June 30,
	2019
Weighted average remaining lease term (years)	8.72
Weighted average discount rate		8.03	%

Components of Lease Cost

The components of lease cost were as follows:

		13 weeks ending		26 weeks ending
		June 30,		June 30,
	Classification	2019		2019
Operating lease cost	Occupancy and General and administrative expenses		11,611		22,606
Variable lease cost	Occupancy		3,649		7,153
Total lease cost		$	15,260	$	29,759

Supplemental Disclosures of Cash Flow Information Related to Leases

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

	13 weeks ending			26 weeks ending
	June 30,			June 30,
	2019			2019
Operating cash flows rent paid for operating lease liabilities		11,788			23,726
Operating right-of-use assets obtained in exchange for new operating lease liabilities		2,735			3,657
Reduction in operating right-of-use assets due to lease terminations		(1,320	)		(5,847	)

Maturities of Lease Liabilities

Maturities of lease liabilities were as follows as of June 30, 2019:

	Operating Leases
Remainder of 2019		23,542
2020		45,919
2021		41,664
2022		36,359
2023		31,492
2024		28,775
Thereafter		135,169
Total lease payments		342,920
Less: imputed interest		(102,896	)
Present value of lease liabilities	$	240,024

Maturities of Lease Liabilities Under the Previous Lease Accounting

As previously disclosed in our 2018 Annual Report on Form 10-K and under the previous lease accounting, maturities of lease liabilities were as follows as of December 30, 2018:

	Operating Leases
2019		47,918
2020		45,828
2021		41,497
2022		36,120
2023		31,060
Thereafter		138,928
Total minimum lease payments		341,351

Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

A summary of stock option activity for the 26 weeks ended June 30, 2019 is as follows:

Options	Shares (Thousands)			Weighted Average Exercise Price		Aggregate Intrinsic Value (Thousands)		Weighted Average Remaining Term (Years)
Outstanding—December 30, 2018		2,150		$	11.49	$	378		5.13
Granted		—			—
Exercised		(22	)		7.93
Canceled		(198	)		13.54
Outstanding—June 30, 2019		1,930		$	11.32	$	—		5.04
Exercisable—June 30, 2019		1,534		$	11.05	$	—		4.15

Summary of RSU Activity

A summary of RSU activity for the 26 weeks ended June 30, 2019 is as follows:

RSUs	Number of RSUs			Weighted Average Fair Value per Share
Non-vested as of December 30, 2018		247		$	11.99
Granted		306			7.02
Vested		(93	)		6.13
Canceled		(13	)		8.46
Non-vested as of June 30, 2019		447		$	8.68

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

Organization and Other Matters - Schedule of Impact on Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Dec. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 18,066			$ 19,775	$ 34,310		$ 25,530
Accounts receivable, net of allowances of $113 as of December 30, 2018	4,545			4,737
Inventories	3,357			3,482
Prepaid expenses and other current assets	8,182			11,426
Total current assets	34,150			39,420
Property and equipment, net	81,628			87,782
Right-of-use assets for operating leases	216,540
Indefinite-lived intangible assets	3,404			3,404
Goodwill	2,222			2,222
Deferred income taxes				13,385
Deferred expenses, net and other assets	6,898			7,002
Total assets	344,842			153,215
Current liabilities
Accounts payable	4,222			3,835
Accrued expenses	21,303			25,029
Short-term operating lease liabilities	29,126
Accrued income taxes	162			162
Total current liabilities	54,813			29,026
Deferred rent and landlord allowances				22,905
Long-term operating lease liabilities	210,898
Other long-term liabilities	6,255			5,751
Total liabilities	271,966			57,682
Equity
Common stock, $0.01 par value—authorized 200,000,000 shares; outstanding 24,142,586 shares as of December 30, 2018	331			330
Additional paid-in-capital	434,407			432,771
Treasury stock, held at cost, 8,801,154 shares as of December 30, 2018	(111,874)			(108,372)
Accumulated deficit	(250,394)			(229,558)
Total stockholders’ equity	72,470			95,171
Non-controlling interest	406			362
Total equity	72,876	$ 76,088		95,533	$ 119,334	$ 117,333	$ 117,238
Total liabilities and equity	$ 344,842			$ 153,215
ASU 2016-02 (Topic 842) [Member]
Current assets
Cash and cash equivalents			$ 19,775
Accounts receivable, net of allowances of $113 as of December 30, 2018			4,737
Inventories			3,482
Prepaid expenses and other current assets			11,426
Total current assets			39,420
Property and equipment, net			87,782
Right-of-use assets for operating leases			232,477
Indefinite-lived intangible assets			3,404
Goodwill			2,222
Deferred income taxes			13,580
Deferred expenses, net and other assets			7,002
Total assets			385,887
Current liabilities
Accounts payable			3,835
Accrued expenses			23,905
Short-term operating lease liabilities			28,826
Accrued income taxes			162
Total current liabilities			56,728
Long-term operating lease liabilities			228,406
Other long-term liabilities			5,751
Total liabilities			290,885
Equity
Common stock, $0.01 par value—authorized 200,000,000 shares; outstanding 24,142,586 shares as of December 30, 2018			330
Additional paid-in-capital			432,771
Treasury stock, held at cost, 8,801,154 shares as of December 30, 2018			(108,372)
Accumulated deficit			(230,089)
Total stockholders’ equity			94,640
Non-controlling interest			362
Total equity			95,002
Total liabilities and equity			385,887
Adjustments Due to the Adoption of Topic 842 \| ASU 2016-02 (Topic 842) [Member]
Current assets
Right-of-use assets for operating leases			232,477
Deferred income taxes			195
Total assets			232,672
Current liabilities
Accrued expenses			(1,124)
Short-term operating lease liabilities			28,826
Total current liabilities			27,702
Deferred rent and landlord allowances			(22,905)
Long-term operating lease liabilities			228,406
Total liabilities			233,203
Equity
Accumulated deficit			(531)
Total stockholders’ equity			(531)
Total equity			(531)
Total liabilities and equity			$ 232,672

Organization and Other Matters - Schedule of Impact on Consolidated Balance Sheet (Parenthetical) (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Dec. 30, 2018
Nature Of Business And Basis Of Presentation [Line Items]
Allowances on accounts receivable	$ 131		$ 113
Common stock, par value	$ 0.01		$ 0.01
Common stock, authorized	200,000,000		200,000,000
Common stock, outstanding	23,768,375		24,142,586
Treasury stock, shares	9,291,732		8,801,154
ASU 2016-02 (Topic 842) [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Net reduction to opening accumulated deficit		$ 500

Revenue - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
Revenue - Additional Information (Detail) - USD ($)	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Disaggregation Of Revenue [Line Items]
Amount of revenue recognized	$ 105,630,000	$ 110,347,000	$ 203,717,000	$ 213,264,000
Aggregate value of remaining performance obligation on outstanding contracts	3,647,000		3,647,000
Revenue recognized related to prior periods			0	0
January 1, 2018 Liability Ending Balance [Member]
Disaggregation Of Revenue [Line Items]
Amount of revenue recognized	600,000	600,000	1,500,000	1,600,000
Point in Time Sales [Member]
Disaggregation Of Revenue [Line Items]
Amount of revenue recognized	105,500,000	110,200,000	203,300,000	212,900,000
Over Time Sales [Member]
Disaggregation Of Revenue [Line Items]
Amount of revenue recognized	$ 100,000	$ 200,000	$ 400,000	$ 400,000

Revenue - Summary of Current and Noncurrent Contract Liabilities from Contracts with Customers (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($)
Revenue From Contract With Customer [Abstract]
Beginning balance of current contract liability	$ (2,184)
Ending balance of current contract liability	(1,687)
Increase (decrease) in contract liability	(497)
Beginning balance of noncurrent contract liability	(1,631)
Ending balance of noncurrent contract liability	(1,960)
Increase (decrease) in contract liability	$ 329

Revenue - Summary of Expected Revenue Recognition Related to Contract Liabilities (Detail1) $ in Thousands	Jun. 30, 2019 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligations	$ 3,647
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-07-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligations	$ 1,250
Revenue, remaining performance obligation, expected timing of satisfaction, period	6 months
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	$ 288
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
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	$ 246
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	$ 199
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	$ 192
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	$ 1,472
Revenue, remaining performance obligation, expected timing of satisfaction, period

Revenue - Summary of Expected Revenue Recognition Related to Contract Liabilities (Detail) $ in Thousands	Jun. 30, 2019 USD ($)
Revenue From Contract With Customer [Abstract]
Revenue, remaining performance obligations	$ 3,647

Fair Value Measurement - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment charge	$ 0.2	$ 2.1	$ 0.2	$ 4.1
ASU 2016-02
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impaired pre-tax right-of-use assets related to previously impaired shops			$ 0.7

Loss Per Share - Additional Information (Detail)	6 Months Ended
Loss Per Share - Additional Information (Detail)	Jun. 30, 2019 shares
Common Share Options [Member]
Loss Per Share [Line Items]
Potential common shares included in diluted shares outstanding	0

Loss Per Share - Summary of Loss Per Share Calculation (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Loss Per Share [Line Items]
Net loss attributable to Potbelly Corporation	$ (1,866)	$ (360)	$ (20,305)	$ (2,554)
Weighted average common shares outstanding-basic	23,908,095	25,551,386	24,020,567	25,348,121
Weighted average common shares outstanding-diluted	23,908,095	25,551,386	24,020,567	25,348,121
Loss per share available to common stockholders-basic	$ (0.08)	$ (0.01)	$ (0.85)	$ (0.10)
Loss per share available to common stockholders-diluted	$ (0.08)	$ (0.01)	$ (0.85)	$ (0.10)
Common Share Options [Member]
Loss Per Share [Line Items]
Potentially dilutive shares that are considered anti-dilutive	2,376,713	2,557,475	2,381,767	2,829,461

- 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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-Name Accounting Standards Codification
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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			6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Income Tax Disclosure [Abstract]
Income tax expense	$ 246	$ 13,600	$ 302	$ 13,865	$ (202)

Leases - Supplemental Balance Sheet Information Related to Leases (Detail) $ in Thousands	Jun. 30, 2019 USD ($)
Leases [Abstract]
Right-of-use assets	$ 216,540
Short-term lease liabilities	29,126
Long-term lease liabilities	210,898
Total lease liabilities	$ 240,024

Leases - Operating Lease Term and Discount Rate (Detail)	Jun. 30, 2019
Leases [Abstract]
Weighted average remaining lease term (years)	8 years 8 months 19 days
Weighted average discount rate	8.03%

Leases - Components of Lease Cost (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Lessee Lease Description [Line Items]
Total lease cost	$ 15,260	$ 29,759
Occupancy and General and Administrative Expenses [Member]
Lessee Lease Description [Line Items]
Operating lease cost	11,611	22,606
Occupancy Expenses [Member]
Lessee Lease Description [Line Items]
Variable lease cost	$ 3,649	$ 7,153

Leases - Supplemental Disclosures of Cash Flow Information Related to Leases (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Leases [Abstract]
Operating cash flows rent paid for operating lease liabilities	$ 11,788	$ 23,726
Operating right-of-use assets obtained in exchange for new operating lease liabilities	2,735	3,657
Reduction in operating right-of-use assets due to lease terminations	$ (1,320)	$ (5,847)

Leases - Additional Information (Detail) $ in Millions	Jun. 30, 2019 USD ($)
Leases [Abstract]
Additional operating leases payments related to shops not yet open, amount	$ 4.4
Additional operating leases related to shops not yet commence, average term	12 years

Leases - Maturities of Lease Liabilities (Detail) $ in Thousands	Jun. 30, 2019 USD ($)
Operating Leases
Remainder of 2019	$ 23,542
2020	45,919
2021	41,664
2022	36,359
2023	31,492
2024	28,775
Thereafter	135,169
Total lease payments	342,920
Less: imputed interest	(102,896)
Present value of lease liabilities	$ 240,024

Leases - Maturities of Lease Liabilities Under the Previous Lease Accounting (Detail) $ in Thousands	Dec. 30, 2018 USD ($)
Operating Leases
2019	$ 47,918
2020	45,828
2021	41,497
2022	36,120
2023	31,060
Thereafter	138,928
Total minimum lease payments	$ 341,351

Capital Stock - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018	May 08, 2018
Equity Class Of Treasury Stock [Line Items]
Stock repurchase program, authorized amount					$ 65,000,000
Common stock repurchased value	$ 2,323,000	$ 3,386,000	$ 3,467,000	$ 3,449,000
Stock Repurchase Program [Member]
Equity Class Of Treasury Stock [Line Items]
Common stock shares repurchased	350,659		485,659
Common stock repurchased value	$ 2,300,000		$ 3,500,000

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018	Jun. 10, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized stock-based compensation expense				$ 1,464	$ 2,251
Stock units issued				306,000
Stock units issued, grant-date fair value				$ 7.02
Common Share Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized stock-based compensation expense		$ 300	$ 300	$ 600	1,000
Unrecognized stock compensation expense		1,400		$ 1,400
Unrecognized stock compensation expense, recognition period				2022
Restricted Stock Units (RSUs) [Member] \| Non-Employee Board Of Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized stock-based compensation expense		700	$ 1,100	$ 900	$ 1,300
Unrecognized stock compensation expense		$ 2,100		$ 2,100
Unrecognized stock compensation expense, recognition period				2022
Vesting description				The employee grants vest in one-third increments over a three-year period.
Options vesting period				3 years
Restricted Stock Units (RSUs) [Member] \| Non-Employee Board Of Directors [Member] \| First Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				50.00%
Restricted Stock Units (RSUs) [Member] \| Non-Employee Board Of Directors [Member] \| Second Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				50.00%
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
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
Performance Shares \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage of targeted number of shares	0.00%
Performance Shares \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage of targeted number of shares	200.00%
2019 Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total number of shares registered						1,200,000
2019 Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Method used to determine fair value of the options				Black-Scholes option pricing model
Stock options granted		0		0

Stock-Based Compensation - Summary of Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2019 $ / shares shares	Dec. 30, 2018 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding shares, beginning balance \| shares	2,150
Options, exercised \| shares	(22)
Options, canceled \| shares	(198)
Options outstanding shares, ending balance \| shares	1,930	2,150
Options outstanding shares, exercisable \| shares	1,534
Options outstanding weighted average exercise price, beginning balance \| $ / shares	$ 11.49
Options, weighted average exercise price, exercised \| $ / shares	7.93
Options, weighted average exercise price, canceled \| $ / shares	13.54
Options outstanding weighted average exercise price, ending balance \| $ / shares	11.32	$ 11.49
Options outstanding weighted average exercise price, exercisable \| $ / shares	$ 11.05
Options outstanding aggregate intrinsic value \| $		$ 378
Option outstanding weighted average remaining term	5 years 14 days	5 years 1 month 17 days
Options exercisable weighted average remaining term	4 years 1 month 24 days

Stock-Based Compensation - Summary of RSU Activity (Detail) shares in Thousands	6 Months Ended
	Jun. 30, 2019 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of RSUs, Non-vested, beginning balance \| shares	247
Number of RSUs, Granted \| shares	306
Number of RSUs, Vested \| shares	(93)
Number of RSUs, Canceled \| shares	(13)
Number of RSUs, Non-vested, ending balance \| shares	447
Weighted Average Fair Value per Share, Non-vested, beginning balance \| $ / shares	$ 11.99
Weighted Average Fair Value per Share, Granted \| $ / shares	7.02
Weighted Average Fair Value per Share, Vested \| $ / shares	6.13
Weighted Average Fair Value per Share, Canceled \| $ / shares	8.46
Weighted Average Fair Value per Share, Non-vested, ending balance \| $ / shares	$ 8.68

Commitment and Contingencies - Additional Information (Detail)	1 Months Ended
	Oct. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Purported collective and class action lawsuit filed date	October 2017

Subsequent Event - Additional Information (Detail) - Subsequent Event	Aug. 07, 2019 USD ($)
London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member]
Subsequent Event [Line Items]
Credit facility agreement, interest rate	1.75%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member]
Subsequent Event [Line Items]
Credit facility agreement, interest rate	1.25%
JPMorgan Chase Bank, N.A. [Member]
Subsequent Event [Line Items]
Commitment fee, percentage	0.20%
JPMorgan Chase Bank, N.A. [Member] \| Prime Rate [Member] \| Maximum [Member]
Subsequent Event [Line Items]
Credit facility agreement, interest rate	0.50%
JPMorgan Chase Bank, N.A. [Member] \| Prime Rate [Member] \| Minimum [Member]
Subsequent Event [Line Items]
Credit facility agreement, interest rate	0.00%
Revolving Credit Facility [Member] \| JPMorgan Chase Bank, N.A. [Member]
Subsequent Event [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]
Subsequent Event [Line Items]
Credit facility agreement, future increases	$ 20,000,000