XML 122 R107.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Commitments and Contingent Liabilities (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2024 | Dec. 31, 2023
Commitments and Contingent Liabilities [Abstract] |  |
Percentage of the Company's loans secured by real estate | 64.00% |
Guarantor Obligations [Abstract] |  |
Obligation instrument term | 1 year |
Unused Lines of Credit [Member] |  |
Guarantor Obligations [Abstract] |  |
Commitments - maximum potential obligation | $ 459,885 | $ 429,430
Commitments to Extend Credits, Primarily Variable Rate [Member] |  |
Guarantor Obligations [Abstract] |  |
Commitments - maximum potential obligation | 2,378,253 | 2,254,841
Standby Letters of Credit [Member] |  |
Guarantor Obligations [Abstract] |  |
Commitments - maximum potential obligation | 50,832 | 44,735
Loans Sold with Recourse [Member] |  |
Guarantor Obligations [Abstract] |  |
Commitments - maximum potential obligation | $ 24,670 | $ 26,423

X
- Definition Describe the approximate period of the guarantee or each group of similar guarantees, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | nbtb_GuarantorObligationsPeriod
Namespace Prefix: | nbtb_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The percentage of the Company's loans secured by real estate. + References No definition available. + Details
Name: | nbtb_PercentageOfCompanysLoansSecuredByRealEstate
Namespace Prefix: | nbtb_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_CommitmentsAndContingenciesDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 460 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482425/460-10-50-4 + Details
Name: | us-gaap_GuaranteeObligationsMaximumExposure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_GuaranteesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_GuaranteeObligationsByNatureAxis=us-gaap_UnusedLinesOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_GuaranteeObligationsByNatureAxis=us-gaap_CommitmentsToExtendCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_GuaranteeObligationsByNatureAxis=us-gaap_FinancialStandbyLetterOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_GuaranteeObligationsByNatureAxis=nbtb_LoansSoldWithRecourseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |