Note 11 - Fair Value and Interest Rate Risk - Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financial Assets:
Available-for-sale securities	$ 50,057	$ 39,496
Interest rate swap receivable	874	286
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Financial Assets:
Available-for-sale securities	18,183	20,473
Corporate Debt Securities [Member]
Financial Assets:
Available-for-sale securities	16,863	12,974
Subordinated Notes [Member]
Financial Assets:
Available-for-sale securities	8,192	4,564
SBA Loan Pools [Member]
Financial Assets:
Available-for-sale securities	5,320
Reported Value Measurement [Member]
Financial Assets:
Financial assets, total	913,007	895,546
Financial Liabilities:
Financial liabilities, total	895,932	876,862
Estimate of Fair Value Measurement [Member]
Financial Assets:
Financial assets, total	903,775	885,360
Financial Liabilities:
Financial liabilities, total	901,551	875,279
Fair Value, Inputs, Level 1 [Member] \| Reported Value Measurement [Member] \| Brokered Deposits [Member]
Financial Liabilities:
Deposits	196,629	183,600
Fair Value, Inputs, Level 1 [Member] \| Reported Value Measurement [Member] \| Cash and Due from Banks [Member]
Financial Assets:
Cash and cash equivalents	3,157	7,381
Fair Value, Inputs, Level 1 [Member] \| Reported Value Measurement [Member] \| Interest-bearing Deposits [Member]
Financial Assets:
Cash and cash equivalents	46,844	59,056
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Brokered Deposits [Member]
Financial Liabilities:
Deposits	197,053	183,120
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Cash and Due from Banks [Member]
Financial Assets:
Cash and cash equivalents	3,157	7,381
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Interest-bearing Deposits [Member]
Financial Assets:
Cash and cash equivalents	46,844	59,056
Fair Value, Inputs, Level 2 [Member] \| Reported Value Measurement [Member]
Financial Assets:
Available-for-sale securities	1,499	1,485
Other investments	4,963	4,963
Federal Reserve Bank stock	2,889	2,866
Federal Home Loan Bank stock	4,477	4,928
SBA loans held for sale	4,103
Accrued interest receivable	3,538	3,766
Financial Liabilities:
FHLB borrowings	100,000	100,000
Senior notes	11,834	11,778
Subordinated debt	9,745	9,723
Junior subordinated debt owed to unconsolidated trust	8,100	8,094
Accrued interest payable	1,995	1,605
Interest rate swap liability	874	286
Fair Value, Inputs, Level 2 [Member] \| Reported Value Measurement [Member] \| Demand Deposits [Member]
Financial Liabilities:
Deposits	80,772	84,471
Fair Value, Inputs, Level 2 [Member] \| Reported Value Measurement [Member] \| Savings Deposits [Member]
Financial Liabilities:
Deposits	57,390	81,912
Fair Value, Inputs, Level 2 [Member] \| Reported Value Measurement [Member] \| Money Market Deposits [Member]
Financial Liabilities:
Deposits	125,934	85,197
Fair Value, Inputs, Level 2 [Member] \| Reported Value Measurement [Member] \| Negotiable Order of Withdrawal (NOW) Accounts [Member]
Financial Liabilities:
Deposits	23,675	26,100
Fair Value, Inputs, Level 2 [Member] \| Reported Value Measurement [Member] \| Time Deposits [Member]
Financial Liabilities:
Deposits	277,656	282,001
Fair Value, Inputs, Level 2 [Member] \| Reported Value Measurement [Member] \| Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Financial Assets:
Available-for-sale securities	18,183	20,473
Fair Value, Inputs, Level 2 [Member] \| Reported Value Measurement [Member] \| Corporate Debt Securities [Member]
Financial Assets:
Available-for-sale securities	16,863	12,974
Fair Value, Inputs, Level 2 [Member] \| Reported Value Measurement [Member] \| Subordinated Notes [Member]
Financial Assets:
Available-for-sale securities	8,192	4,564
Fair Value, Inputs, Level 2 [Member] \| Reported Value Measurement [Member] \| SBA Loan Pools [Member]
Financial Assets:
Available-for-sale securities	5,320
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member]
Financial Assets:
Available-for-sale securities	1,499	1,485
Other investments	4,963	4,963
Federal Reserve Bank stock	2,889	2,866
Federal Home Loan Bank stock	4,477	4,928
SBA loans held for sale	4,480
Accrued interest receivable	3,538	3,766
Financial Liabilities:
FHLB borrowings	104,559	101,369
Senior notes	11,698	11,293
Subordinated debt	9,776	9,348
Junior subordinated debt owed to unconsolidated trust	8,100	8,094
Accrued interest payable	1,995	1,605
Interest rate swap liability	874	286
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Demand Deposits [Member]
Financial Liabilities:
Deposits	80,772	84,471
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Savings Deposits [Member]
Financial Liabilities:
Deposits	57,390	81,912
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Money Market Deposits [Member]
Financial Liabilities:
Deposits	125,934	85,197
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Negotiable Order of Withdrawal (NOW) Accounts [Member]
Financial Liabilities:
Deposits	23,675	26,100
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Time Deposits [Member]
Financial Liabilities:
Deposits	278,452	280,538
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Financial Assets:
Available-for-sale securities	18,183	20,473
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Corporate Debt Securities [Member]
Financial Assets:
Available-for-sale securities	16,863	12,974
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Subordinated Notes [Member]
Financial Assets:
Available-for-sale securities	8,192	4,564
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| SBA Loan Pools [Member]
Financial Assets:
Available-for-sale securities	5,320
Fair Value, Inputs, Level 3 [Member]
Financial Assets:
SBA servicing assets		37
Fair Value, Inputs, Level 3 [Member] \| Reported Value Measurement [Member]
Financial Assets:
Loans receivable, net	791,909	772,767
SBA servicing assets	196	37
Financial Liabilities:
Note payable	1,242	1,388
Contingent consideration liability	86	707
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member]
Financial Assets:
Loans receivable, net	782,220	762,581
SBA servicing assets	276	37
Financial Liabilities:
Note payable	1,187	1,239
Contingent consideration liability	$ 86	$ 707

Fair value portion of the Federal Reserve Bank Stock.

No definition available.

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

- Definition

Fair value portion of interest receivable.

+ References

No definition available.

+ Details

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

- Definition

Fair value of junior subordinated debt owned to unconsolidated trust.

+ References

No definition available.

+ Details

Name:	pnbk_JuniorSubordinatedDebtOwedToUnconsolidatedTrustFairValue
Namespace Prefix:	pnbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of investments classified as other.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of senior notes.

+ References

No definition available.

+ Details

Name:	pnbk_SeniorNotesFairValueDisclosure
Namespace Prefix:	pnbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of accrued expenses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

+ Details

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
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 portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

No definition available.

+ Details

Name:	us-gaap_CashAndCashEquivalentsFairValueDisclosure
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

+ Details

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

- Definition

Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

+ References

No definition available.

+ Details

Name:	us-gaap_DepositsFairValueDisclosure
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

- Definition

Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

+ 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 (b)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

Reference 2: 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_FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13(3)(a))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of investments in Federal Home Loan Bank (FHLBank) stock.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2196772

+ Details

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

- Definition

Fair value portion of notes payable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20,22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Aggregate amount of servicing assets that are subsequently measured at fair value and servicing assets that are subsequently measured using the amortization method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

+ Details

Name:	us-gaap_ServicingAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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=pnbk_SBALoanPoolsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
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_FairValueByLiabilityClassAxis=pnbk_BrokeredDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CashAndCashEquivalentsAxis=pnbk_CashAndDueFromBanksMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CashAndCashEquivalentsAxis=us-gaap_InterestBearingDepositsMember
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_FairValueByLiabilityClassAxis=pnbk_DemandDeposits1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=pnbk_SavingsDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=pnbk_MoneyMarketDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=pnbk_NegotiableOrderOfWithdrawalNowAccountsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=pnbk_TimeDepositsMember
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: