Name:	nwbi_FinancingReceivableModificationsAmountPaidOff
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Data Type:	xbrli:monetaryItemType
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Financing Receivable, Modifications, Charge-Offs

No definition available.

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- References

No definition available.

Name:	nwbi_FinancingReceivableModificationsNumberOfContractRollForward
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Number additions during the period of financing receivables that have been modified by troubled debt restructurings.

No definition available.

Name:	nwbi_FinancingReceivableModificationsNumberOfContracts2Additions
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Data Type:	xbrli:integerItemType
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The number of financing receivables that have been modified by troubled debt restructurings and were charged off during the reporting period.

No definition available.

Name:	nwbi_FinancingReceivableModificationsNumberOfContractsChargedOff
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Financing Receivable, Modifications, Number Of Contracts, Net Paydowns

No definition available.

Name:	nwbi_FinancingReceivableModificationsNumberOfContractsNetPaydowns
Namespace Prefix:	nwbi_
Data Type:	xbrli:integerItemType
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The number of financing receivables that have been modified by troubled debt restructurings and were paid off during the reporting period.

No definition available.

Name:	nwbi_FinancingReceivableModificationsNumberOfContractsPaidOff
Namespace Prefix:	nwbi_
Data Type:	xbrli:integerItemType
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Number of financing receivables that have been re-modified by troubled debt restructurings.

No definition available.

Name:	nwbi_FinancingReceivableModificationsNumberOfContractsRemodified
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Data Type:	xbrli:integerItemType
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Financing Receivable Modifications, Outstanding Number Of Contracts

No definition available.

Name:	nwbi_FinancingReceivableModificationsOutstandingNumberOfContracts
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Data Type:	xbrli:integerItemType
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The accruing portion of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

No definition available.

Name:	nwbi_FinancingReceivableModificationsRecordedInvestmentAccrual
Namespace Prefix:	nwbi_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

The amount of additions during the period in recorded investment related to financing receivables that has been modified by troubled debt restructurings.

No definition available.

Name:	nwbi_FinancingReceivableModificationsRecordedInvestmentAdditions
Namespace Prefix:	nwbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The amount of net paydowns out of recorded investment related to financing receivables that have been modified by troubled debt restructurings.

No definition available.

Name:	nwbi_FinancingReceivableModificationsRecordedInvestmentNetPaydowns
Namespace Prefix:	nwbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The non-accruing portion of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

No definition available.

Name:	nwbi_FinancingReceivableModificationsRecordedInvestmentNonAccrual
Namespace Prefix:	nwbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of the recorded investment related to existing financing receivables that were previously modified by troubled debt restructurings and have subsequently been re-modified during the period.

No definition available.

Name:	nwbi_FinancingReceivableModificationsRecordedInvestmentReModifications
Namespace Prefix:	nwbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

Name:	nwbi_FinancingReceivableModificationsRecordedInvestmentRollForward
Namespace Prefix:	nwbi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of financing receivable modified as troubled debt restructuring.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI https://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI https://asc.fasb.org/extlink&oid=121585226&loc=d3e18845-111554

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