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Derivatives and Hedging Activities - Additional Information (Details) - Interest Rate Swap	12 Months Ended
	Dec. 31, 2020 USD ($) derivative loan	Dec. 31, 2019 USD ($) loan derivative	Oct. 31, 2018 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Participating Mortgage Loans, Mortgage Obligations, Amount	$ 27,700,000	$ 37,400,000
Number of Participation loans purchased | loan	4	5
Cash flow hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount			$ 400,000,000
Derivative, Fixed Interest Rate			3.018%
Expected interest income on termination	$ 2,000,000.0
Not Designated as Hedging Instrument
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of Interest Rate Derivatives Held | derivative	19	19
Valley Bank | Not Designated as Hedging Instrument
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	$ 584,000
Number of Interest Rate Derivatives Held | derivative	2

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- Definition

Amount of interest income expected upon termination of a derivative contract.

+ References

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- Definition

Number of participation loans purchased during the period.

+ References

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- Definition

Fixed interest rate related to the interest rate derivative.

+ References

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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959

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- Definition

Number of interest rate derivative instruments held by the entity at the reporting date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
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-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959

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-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959

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- Definition

The aggregate amount of the participating mortgage obligation at the end of the accounting period.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 30
-Section 50
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=99377297&loc=d3e10013-112621

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