Related Party Transactions (Details)	Dec. 31, 2019 USD ($)
Related Party Transactions [Abstract]
2020	$ 183,368
2021	188,869
2022	194,535
2023	200,371
2024	76,244
Total	$ 843,387

Related party transaction, operating leases, future minimum payments due.

No definition available.

Name:	pstl_RelatedPartyTransactionOperatingLeasesFutureMinimumPaymentsDue
Namespace Prefix:	pstl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Related party transaction, operating leases, future minimum payments due in five years.

No definition available.

Name:	pstl_RelatedPartyTransactionOperatingLeasesFutureMinimumPaymentsDueInFiveYears
Namespace Prefix:	pstl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Related party transaction, operating leases, future minimum payments due in four years.

No definition available.

Name:	pstl_RelatedPartyTransactionOperatingLeasesFutureMinimumPaymentsDueInFourYears
Namespace Prefix:	pstl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Related party transaction, operating leases, future minimum payments due in three years.

No definition available.

Name:	pstl_RelatedPartyTransactionOperatingLeasesFutureMinimumPaymentsDueInThreeYears
Namespace Prefix:	pstl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Related party transaction, operating leases, future minimum payments due in two years.

No definition available.

Name:	pstl_RelatedPartyTransactionOperatingLeasesFutureMinimumPaymentsDueInTwoYears
Namespace Prefix:	pstl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Related party transaction, operating leases, future minimum payments due, next twelve months.

No definition available.

Name:	pstl_RelatedPartyTransactionOperatingLeasesFutureMinimumPaymentsDueNextTwelveMonths
Namespace Prefix:	pstl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

No definition available.

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