FAIR VALUE (Schedule of Assets Measured on a Recurring Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Securities available for sale	$ 390,755	$ 377,936
Loans held for sale, at fair value	2,881	1,576
Recurring Basis [Member]
Loans held for sale, at fair value	2,881	1,576
Total	436,974	395,577
Derivatives	36,169	10,538
Recurring Basis [Member] \| Quoted Prices in Active Market For Identical Assets (Level 1) [Member]
Total	10,836	4,719
Recurring Basis [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Loans held for sale, at fair value	2,881	1,576
Total	426,138	390,858
Derivatives	36,169	10,538
Recurring Basis [Member] \| Designated as Hedging Instrument [Member]
Derivatives	121	1,657
Derivatives	3,788	849
Recurring Basis [Member] \| Designated as Hedging Instrument [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Derivatives	121	1,657
Derivatives	3,788	849
Recurring Basis [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives	32,381	9,689
Derivatives	32,381	9,689
Recurring Basis [Member] \| Not Designated as Hedging Instrument [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Derivatives	32,381	9,689
Derivatives	32,381	9,689
U.S. Government-Sponsored Agencies [Member]
Securities available for sale	34,784	102,013
U.S. Government-Sponsored Agencies [Member] \| Recurring Basis [Member]
Securities available for sale	34,784	102,013
U.S. Government-Sponsored Agencies [Member] \| Recurring Basis [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale	34,784	102,013
Mortgage-Backed Securities-Residential [Member]
Securities available for sale	338,904	251,362
Mortgage-Backed Securities-Residential [Member] \| Recurring Basis [Member]
Securities available for sale	338,904	251,362
Mortgage-Backed Securities-Residential [Member] \| Recurring Basis [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale	338,904	251,362
SBA Pool Securities [Member]
Securities available for sale	2,784	3,839
SBA Pool Securities [Member] \| Recurring Basis [Member]
Securities available for sale	2,784	3,839
SBA Pool Securities [Member] \| Recurring Basis [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale	2,784	3,839
State and Political Subdivisions [Member]
Securities available for sale	11,215	17,610
State and Political Subdivisions [Member] \| Recurring Basis [Member]
Securities available for sale	11,215	17,610
State and Political Subdivisions [Member] \| Recurring Basis [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale	11,215	17,610
Corporate Bond [Member]
Securities available for sale	3,068	3,112
Corporate Bond [Member] \| Recurring Basis [Member]
Securities available for sale	3,068	3,112
Corporate Bond [Member] \| Recurring Basis [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale	3,068	3,112
CRA Investment Fund [Member] \| Recurring Basis [Member]
Securities available for sale	10,836	4,719
CRA Investment Fund [Member] \| Recurring Basis [Member] \| Quoted Prices in Active Market For Identical Assets (Level 1) [Member]
Securities available for sale	$ 10,836	$ 4,719

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

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_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, 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 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

- 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_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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