XML 79 R68.htm IDEA: XBRL DOCUMENT
v3.25.3

LOAN SERVICING - Schedule of Sensitivity of Fair Value to Changes in Key Assumptions (Details) - Mortgage Servicing Rights - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2025 | Dec. 31, 2024
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items] |  |
Weighted average life (months) | 90 months | 96 months
Constant prepayment rate (annualized) | 8.60% | 7.60%
Discount rate | 10.10% | 10.30%
Sensitivity analysis of fair value, change in interest rates, plus 2.00% | $ 13 | $ 6
Sensitivity analysis of fair value, change in interest rates, plus 1.00% | 10 | 5
Sensitivity analysis of fair value, change in interest rates, plus 0.50% | 7 | 3
Sensitivity analysis of fair value, change in interest rates, plus 0.25% | 4 | 2
Sensitivity analysis of fair value, change in interest rates, minus 0.25% | (4) | (2)
Sensitivity analysis of fair value, change in interest rates, minus 0.50% | (7) | (5)
Sensitivity analysis of fair value, change in interest rates, minus 1.00% | (13) | (11)
Sensitivity analysis of fair value, change in interest rates, minus 2.00% | (23) | (20)
Sensitivity analysis of fair value, change in interest rates, minus 3.00% | $ (41) | $ (34)

X
- Definition Assumption for fair value on securitization date of interests continued to be held by transferor servicing assets or liabilities annualized constant prepayment rate. + References No definition available. + Details
Name: | fnb_AssumptionForFairValueOnSecuritizationDateOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesAnnualizedConstantPrepaymentRate
Namespace Prefix: | fnb_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Sensitivity Analysis Of Fair Value Of Interests Continued To Be Held By Transferor Servicing Assets Or Liabilities Impact Of One Point Zero Percent Adverse Change In Prepayment Speed + References No definition available. + Details
Name: | fnb_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfOnePointZeroPercentAdverseChangeInPrepaymentSpeed
Namespace Prefix: | fnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Sensitivity analysis of fair value of interests continued to be held by transferor servicing assets or liabilities impact of one point zero percent favorable change in prepayment speed. + References No definition available. + Details
Name: | fnb_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfOnePointZeroPercentFavorableChangeInPrepaymentSpeed
Namespace Prefix: | fnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Sensitivity Analysis Of Fair Value Of Interests Continued To Be Held By Transferor Servicing Assets Or Liabilities Impact Of Three Point Zero Percent Adverse Change In Prepayment Speed + References No definition available. + Details
Name: | fnb_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfThreePointZeroPercentAdverseChangeInPrepaymentSpeed
Namespace Prefix: | fnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Sensitivity Analysis Of Fair Value Of Interests Continued To Be Held By Transferor Servicing Assets Or Liabilities Impact Of Two Point Zero Percent Adverse Change In Prepayment Speed + References No definition available. + Details
Name: | fnb_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfTwoPointZeroPercentAdverseChangeInPrepaymentSpeed
Namespace Prefix: | fnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Sensitivity analysis of fair value of interests continued to be held by transferor servicing assets or liabilities impact of two point zero percent favorable change in prepayment speed. + References No definition available. + Details
Name: | fnb_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfTwoPointZeroPercentFavorableChangeInPrepaymentSpeed
Namespace Prefix: | fnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Sensitivity analysis of fair value of interests continued to be held by transferor servicing assets or liabilities impact of zero point five zero percent adverse change in prepayment speed. + References No definition available. + Details
Name: | fnb_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfZeroPointFiveZeroPercentAdverseChangeInPrepaymentSpeed
Namespace Prefix: | fnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Sensitivity analysis of fair value of interests continued to be held by transferor servicing assets or liabilities impact of zero point five zero percent favorable change in prepayment speed. + References No definition available. + Details
Name: | fnb_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfZeroPointFiveZeroPercentFavorableChangeInPrepaymentSpeed
Namespace Prefix: | fnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Sensitivity analysis of fair value of interests continued to be held by transferor servicing assets or liabilities impact of zero point two five percent adverse change in prepayment speed. + References No definition available. + Details
Name: | fnb_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfZeroPointTwoFivePercentAdverseChangeInPrepaymentSpeed
Namespace Prefix: | fnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Sensitivity analysis of fair value of interests continued to be held by transferor servicing assets or liabilities impact of zero point two five percent favorable change in prepayment speed. + References No definition available. + Details
Name: | fnb_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfZeroPointTwoFivePercentFavorableChangeInPrepaymentSpeed
Namespace Prefix: | fnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- 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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481326/860-20-50-4 + Details
Name: | us-gaap_AssumptionForFairValueAsOfBalanceSheetDateOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Discount rate which is used to value residual cash flows generated by financial assets of the securitization, asset-backed financing arrangement, or similar transfer for initial fair value measurement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481326/860-20-50-3 + Details
Name: | us-gaap_AssumptionForFairValueOnSecuritizationDateOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average life of securitized assets for initial fair value measurement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481326/860-20-50-3 + Details
Name: | us-gaap_FairValueAssumptionDateOfSecuritizationOrAssetBackedFinancingArrangementTransferorsContinuingInvolvementServicingAssetsOrLiabilitiesWeightedAverageLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=fnb_MortgageLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |