Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5258-111524

+ Details

Name:	us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953550-111524

+ Details

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

- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

+ Details

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

- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of average investment of impaired financing receivables for which there is no related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5258-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of interest income, recognized on accrual basis, on financing receivables that are recognized as impaired, for which there is no related allowance for credit losses.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of unpaid principal balance of impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of average investment of impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of interest income, recognized on accrual basis, on financing receivables, for which there is a related allowance for credit losses and are recognized as impaired.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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

- Definition

Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=plbc_CommercialLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=plbc_AgriculturalLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_RealEstateLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=plbc_EquityLinesOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_AutomobileLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=plbc_OtherLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 4 - Loans and the Allowance for Loan Losses - Impaired Loans (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Recorded investment with no related allowance recorded	$ 1,709,000		$ 1,705,000
Recorded investment with an allowance	538,000		539,000
Impaired Financing Receivable, Related Allowance	154,000		154,000
Recorded investment	2,247,000		2,244,000
Unpaid principal balance	2,355,000		2,399,000
Average recorded investment	2,256,000	$ 1,352,000	1,777,000
Interest income recognized	15,000	$ 18,000	62,000
Commercial Portfolio Segment [Member] \| Commercial Loans [Member]
Recorded investment with no related allowance recorded			25,000
Unpaid principal balance with no related allowance recorded			85,000
Average recorded investment with no related allowance recorded			23,000
Interest income recognized with no related allowance recorded
Recorded investment with an allowance
Unpaid principal balance with allowance
Impaired Financing Receivable, Related Allowance
Average recorded investment with an allowance
Interest income recognized with an allowance
Recorded investment			25,000
Unpaid principal balance			85,000
Average recorded investment			23,000
Interest income recognized
Commercial Portfolio Segment [Member] \| Agricultural Loans [Member]
Recorded investment with no related allowance recorded	247,000		248,000
Unpaid principal balance with no related allowance recorded	247,000		248,000
Average recorded investment with no related allowance recorded	248,000		249,000
Interest income recognized with no related allowance recorded	5,000		19,000
Recorded investment with an allowance
Unpaid principal balance with allowance
Impaired Financing Receivable, Related Allowance
Average recorded investment with an allowance
Interest income recognized with an allowance
Recorded investment	247,000		248,000
Unpaid principal balance	247,000		248,000
Average recorded investment	248,000		249,000
Interest income recognized	5,000		19,000
Commercial Portfolio Segment [Member] \| Real Estate Loan [Member]
Recorded investment with no related allowance recorded	553,000		563,000
Unpaid principal balance with no related allowance recorded	611,000		614,000
Average recorded investment with no related allowance recorded	558,000		476,000
Interest income recognized with no related allowance recorded
Recorded investment with an allowance	252,000		252,000
Unpaid principal balance with allowance	265,000		261,000
Impaired Financing Receivable, Related Allowance	121,000		121,000
Average recorded investment with an allowance	252,000		139,000
Interest income recognized with an allowance
Recorded investment	805,000		815,000
Unpaid principal balance	876,000		875,000
Average recorded investment	810,000		615,000
Interest income recognized	0
Commercial Portfolio Segment [Member] \| Construction Loans [Member]
Recorded investment with no related allowance recorded
Unpaid principal balance with no related allowance recorded
Average recorded investment with no related allowance recorded
Interest income recognized with no related allowance recorded
Recorded investment with an allowance	109,000		110,000
Unpaid principal balance with allowance	109,000		110,000
Impaired Financing Receivable, Related Allowance	5,000		5,000
Average recorded investment with an allowance	109,000		114,000
Interest income recognized with an allowance	1,000		7,000
Recorded investment	109,000		110,000
Unpaid principal balance	109,000		110,000
Average recorded investment	109,000		114,000
Interest income recognized	1,000		7,000
Residential Portfolio Segment [Member] \| Real Estate Loan [Member]
Recorded investment with no related allowance recorded	479,000		435,000
Unpaid principal balance with no related allowance recorded	489,000		447,000
Average recorded investment with no related allowance recorded	480,000		385,000
Interest income recognized with no related allowance recorded	7,000		29,000
Recorded investment with an allowance	177,000		177,000
Unpaid principal balance with allowance	176,000		177,000
Impaired Financing Receivable, Related Allowance	28,000		28,000
Average recorded investment with an allowance	177,000		178,000
Interest income recognized with an allowance	2,000		7,000
Recorded investment	656,000		612,000
Unpaid principal balance	665,000		624,000
Average recorded investment	657,000		563,000
Interest income recognized	9,000		36,000
Residential Portfolio Segment [Member] \| Equity Lines of Credit [Member]
Recorded investment with no related allowance recorded	430,000		434,000
Unpaid principal balance with no related allowance recorded	458,000		457,000
Average recorded investment with no related allowance recorded	432,000		213,000
Interest income recognized with no related allowance recorded
Recorded investment with an allowance
Unpaid principal balance with allowance
Impaired Financing Receivable, Related Allowance
Average recorded investment with an allowance
Interest income recognized with an allowance
Recorded investment	430,000		434,000
Unpaid principal balance	458,000		457,000
Average recorded investment	432,000		213,000
Interest income recognized	0
Consumer Portfolio Segment [Member] \| Automobile Loan [Member]
Recorded investment with no related allowance recorded
Unpaid principal balance with no related allowance recorded
Average recorded investment with no related allowance recorded
Interest income recognized with no related allowance recorded
Recorded investment with an allowance
Unpaid principal balance with allowance
Impaired Financing Receivable, Related Allowance
Average recorded investment with an allowance
Interest income recognized with an allowance
Recorded investment
Unpaid principal balance
Average recorded investment
Interest income recognized
Consumer Portfolio Segment [Member] \| Other Loans [Member]
Recorded investment with no related allowance recorded
Unpaid principal balance with no related allowance recorded
Average recorded investment with no related allowance recorded
Interest income recognized with no related allowance recorded
Recorded investment with an allowance
Unpaid principal balance with allowance
Impaired Financing Receivable, Related Allowance
Average recorded investment with an allowance
Interest income recognized with an allowance
Recorded investment
Unpaid principal balance
Average recorded investment
Interest income recognized