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

Lessee operating lease lease not yet commenced amount.

No definition available.

Name:	pbpb_LesseeOperatingLeaseLeaseNotYetCommencedAmount
Namespace Prefix:	pbpb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant