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