Note 10 - Fair Value Measurement - Assets and Liabilities Measured at Fair Value on a Non-recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Other real estate, Total gain (loss)
Asset, Total gain (loss)	61	3
Commercial Portfolio Segment [Member] \| Construction Loans [Member]
Impaired loans, Total gain (loss)	61	3
Other real estate, Total gain (loss)
Commercial Portfolio Segment [Member] \| Real Estate Loan [Member]
Other real estate, Total gain (loss)
Residential Portfolio Segment [Member] \| Real Estate Loan [Member]
Other real estate, Total gain (loss)
Fair Value, Nonrecurring [Member]
Other real estate	1,170	1,170
Assets	1,588	1,170
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Other real estate	1,170	1,170
Assets	1,588	1,170
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Other real estate
Assets
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Other real estate
Assets
Fair Value, Nonrecurring [Member] \| Commercial Portfolio Segment [Member] \| Construction Loans [Member]
Impaired loans	418
Other real estate	455	455
Fair Value, Nonrecurring [Member] \| Commercial Portfolio Segment [Member] \| Construction Loans [Member] \| Fair Value, Inputs, Level 3 [Member]
Impaired loans	418
Other real estate	455	455
Fair Value, Nonrecurring [Member] \| Commercial Portfolio Segment [Member] \| Construction Loans [Member] \| Fair Value, Inputs, Level 1 [Member]
Other real estate
Fair Value, Nonrecurring [Member] \| Commercial Portfolio Segment [Member] \| Construction Loans [Member] \| Fair Value, Inputs, Level 2 [Member]
Other real estate
Fair Value, Nonrecurring [Member] \| Commercial Portfolio Segment [Member] \| Real Estate Loan [Member]
Impaired loans	418
Other real estate	347	347
Fair Value, Nonrecurring [Member] \| Commercial Portfolio Segment [Member] \| Real Estate Loan [Member] \| Fair Value, Inputs, Level 3 [Member]
Other real estate	347	347
Fair Value, Nonrecurring [Member] \| Residential Portfolio Segment [Member] \| Real Estate Loan [Member]
Other real estate	368	368
Fair Value, Nonrecurring [Member] \| Residential Portfolio Segment [Member] \| Real Estate Loan [Member] \| Fair Value, Inputs, Level 3 [Member]
Other real estate	368	368
Fair Value, Nonrecurring [Member] \| Residential Portfolio Segment [Member] \| Real Estate Loan [Member] \| Fair Value, Inputs, Level 1 [Member]
Other real estate
Fair Value, Nonrecurring [Member] \| Residential Portfolio Segment [Member] \| Real Estate Loan [Member] \| Fair Value, Inputs, Level 2 [Member]
Other real estate

Represents the amount of gain (loss) on fair value adjustments of impaired loans during the period.

No definition available.

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Namespace Prefix:	plbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the amount of gain (loss) on fair value adjustments of other real estate during the period.

+ References

No definition available.

+ Details

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Namespace Prefix:	plbc_
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Balance Type:	credit
Period Type:	duration

- Definition

Represents fair value portion of impaired loans.

+ References

No definition available.

+ Details

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Namespace Prefix:	plbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

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

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Period Type:	instant

- Definition

Amount of gain (loss) from the difference between the sale price or salvage price and the book value of an asset that was sold or retired, and gain (loss) from the write down of assets from their carrying value to fair value.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

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- Definition

Carrying amount of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This does not include real estate assets taken in settlement of troubled loans through surrender or foreclosure.

+ 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 210.9-03.10(4))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- Details

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