Debt Instrument, Amount Outstanding After Repurchase

No definition available.

Name:	nwbi_DebtInstrumentAmountOutstandingAfterRepurchase
Namespace Prefix:	nwbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the maximum period for which interest payment on the subordinated debentures can be deferred.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the amount of interest payment deferred on the subordinated debentures of the entity.

+ References

No definition available.

+ Details

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Namespace Prefix:	nwbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt Instrument, Number Of Advances

+ References

No definition available.

+ Details

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Namespace Prefix:	nwbi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Issuance Costs Amortization Period

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number Of Statutory Business Trusts

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value amount of debt instrument that was repurchased.

+ References

No definition available.

+ Details

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

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

The carrying value as of the balance sheet date of the assets received as collateral against securities loaned to other broker-dealers. Borrowers of securities generally are required to provide collateral to the lenders of securities, commonly cash but sometimes other securities or standby letters of credit, with a value slightly higher than that of the securities borrowed. In instances where the entity is permitted to sell or re-pledge these securities, the entity reports the fair value of the collateral received and the related obligation to return the collateral as a liability.

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+ Details

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

- Definition

Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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+ Details

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

- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

+ References

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+ Details

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

- Definition

For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, average borrowings during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1402
-Paragraph (a)

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-Name Regulation S-K (SK)
-Number 229
-Section 1402
-Paragraph (b)
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+ Details

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

- Definition

For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, the maximum amount borrowed at any time during the period.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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- Details

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- Details

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- Details

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- Details

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Borrowed Funds - Narrative (Details) $ in Thousands		12 Months Ended
Borrowed Funds - Narrative (Details) $ in Thousands	Sep. 09, 2020 USD ($)	Dec. 31, 2022 USD ($) advance business_trust	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Number of advances \| advance		5
Borrowed funds		$ 681,166	$ 139,093
Number of statutory business trusts \| business_trust		7
Trust Preferred Securities Subject to Mandatory Redemption
Debt Instrument [Line Items]
Maximum period for which interest payment on the subordinated debentures can be deferred		5 years
Interest deferral		$ 0
Collateralized borrowings, due within one year
Debt Instrument [Line Items]
Due within one year, amount		105,800	139,100
Average amount of agreements outstanding		115,400	132,100
Maximum amount of outstanding security repurchase agreement		135,700	139,600
Borrowed funds		105,766	139,093
Collateral received, due within one year
Debt Instrument [Line Items]
Collateral received		24,100	0
Borrowed funds		24,100	0
Term notes payable to the FHLB of Pittsburgh, due within one year
Debt Instrument [Line Items]
Debt issued		500,000	0
Term notes payable to the FHLB of Pittsburgh, due within one year \| Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Debt issued		$ 100,000
Stated rate		4.54%
Term notes payable to the FHLB of Pittsburgh, due within one year \| Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Debt issued		$ 100,000
Stated rate		4.53%
Term notes payable to the FHLB of Pittsburgh, due within one year \| Debt Instrument, Redemption, Period Three
Debt Instrument [Line Items]
Debt issued		$ 100,000
Stated rate		4.57%
Term notes payable to the FHLB of Pittsburgh, due within one year \| Debt Instrument, Redemption, Period Four
Debt Instrument [Line Items]
Debt issued		$ 100,000
Stated rate		4.54%
Term notes payable to the FHLB of Pittsburgh, due within one year \| Debt Instrument, Redemption, Period Five
Debt Instrument [Line Items]
Debt issued		$ 100,000
Stated rate		4.58%
Subordinated Debt
Debt Instrument [Line Items]
Debt issued	$ 125,000
Stated rate	4.00%
Spread on variable rate basis (as a percent)	3.89%
Amount repurchased		$ 10,200
Amount outstanding after repurchase		114,800
Debt issuance costs	$ 1,800
Debt issuance amortization period	5 years
Borrowed funds		113,800	123,600
Federal Home Loan Bank of Pittsburgh \| Notes payable to the FHLB of Pittsburgh, due within one year
Debt Instrument [Line Items]
Maximum commitment		250,000
Long-term line of credit		51,300	0
Borrowed funds		51,300	0
Federal Home Loan Bank of Pittsburgh \| Term notes payable to the FHLB of Pittsburgh, due within one year
Debt Instrument [Line Items]
Borrowed funds		$ 500,000	$ 0