XML 74 R63.htm IDEA: XBRL DOCUMENT
v3.25.2

Allowance for Credit Losses and Credit Quality of Loans, Financial Effect of Modifications Made to Borrowers Experiencing Financial Difficulty (Details) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024
Interest Rate Reduction [Member] |  |  |  |
Financing Receivable Financial Effect of Modifications Made to Borrowers Experiencing Financial Difficulty [Abstract] |  |  |  |
Decrease in weighted average contractual interest rate | 0.62% | 1.00% | 0.62% | 1.00%
Residential [Member] | Term Extension [Member] |  |  |  |
Financing Receivable Financial Effect of Modifications Made to Borrowers Experiencing Financial Difficulty [Abstract] |  |  |  |
Period of increase in weighted-average maturity | 9 years 9 months 18 days | 5 years 3 months 18 days | 7 years 6 months | 6 years 3 months 18 days

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

X
- Definition Percentage of decrease in weighted average contractual interest rate of financing receivable modified for debtor experiencing financial difficulty. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 12A -Publisher FASB -URI https://asc.fasb.org/1943274/2147481933/310-10-55-12A + Details
Name: | us-gaap_FinancingReceivableModifiedWeightedAverageInterestRateDecreaseFromModification
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period of increase in weighted average maturity of financing receivable modified for debtor experiencing financial difficulty, 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/exampleRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 12A -Publisher FASB -URI https://asc.fasb.org/1943274/2147481933/310-10-55-12A + Details
Name: | us-gaap_FinancingReceivableModifiedWeightedAverageTermIncreaseFromModification
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityAndInterestRateReductionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |