XML 49 R38.htm IDEA: XBRL DOCUMENT v3.19.1

Leases - Additional Information (Detail) $ in Millions	Mar. 31, 2019 USD ($)
Leases [Abstract]
Additional operating leases related to shops not yet open, amount	$ 1.6
Additional operating leases related to shops not yet commence, term	7 years

X

- Definition

Lessee operating lease lease not yet commenced amount.

+ References

No definition available.

+ Details

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

X

- References

No definition available.

+ Details

Name:	us-gaap_LeasesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Term of lessee's operating lease not yet commenced, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant