Note 11 - Fair Value and Interest Rate Risk - Financial Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Available-for-sale securities	$ 40,275	$ 39,496
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities	19,976	20,473
Corporate Debt Securities [Member]
Available-for-sale securities	12,828	12,974
Subordinated Notes [Member]
Available-for-sale securities	5,980	4,564
US Treasury Securities [Member]
Available-for-sale securities	1,491	1,485
Fair Value, Recurring [Member]
Available-for-sale securities	40,275	39,496
Impaired PCI Loans, net	439	615
Contingent consideration liability	86	707
Interest swap receivable	417	286
Interest swap liability	417	286
Fair Value, Recurring [Member] \| Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities	19,976	20,473
Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Available-for-sale securities	12,828	12,974
Fair Value, Recurring [Member] \| Subordinated Notes [Member]
Available-for-sale securities	5,980	4,564
Fair Value, Recurring [Member] \| US Treasury Securities [Member]
Available-for-sale securities	1,491	1,485
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Available-for-sale securities
Impaired PCI Loans, net
Contingent consideration liability
Interest swap receivable
Interest swap liability
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Available-for-sale securities
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Subordinated Notes [Member]
Available-for-sale securities
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| US Treasury Securities [Member]
Available-for-sale securities
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Available-for-sale securities	40,275	39,496
Impaired PCI Loans, net
Contingent consideration liability
Interest swap receivable	417	286
Interest swap liability	417	286
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities	19,976	20,473
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Available-for-sale securities	12,828	12,974
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Subordinated Notes [Member]
Available-for-sale securities	5,980	4,564
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| US Treasury Securities [Member]
Available-for-sale securities	1,491	1,485
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Available-for-sale securities
Impaired PCI Loans, net	439	615
Contingent consideration liability	86	707
Interest swap receivable
Interest swap liability
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Available-for-sale securities
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Subordinated Notes [Member]
Available-for-sale securities
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| US Treasury Securities [Member]
Available-for-sale securities

Fair value portion of impaired PCI loans receivables.

No definition available.

Name:	pnbk_ImpairedPCILoansFairValue
Namespace Prefix:	pnbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of contingent consideration in a business combination that is classified in shareholders' equity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_ContingentConsiderationClassifiedAsEquityFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13433-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

+ Details

Name:	us-gaap_DerivativeAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13433-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

+ Details

Name:	us-gaap_DerivativeLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=pnbk_SubordinatedNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: