XML 66 R55.htm IDEA: XBRL DOCUMENT
v3.24.1.u1

Allowance for Credit Losses and Credit Quality of Loans, Performance of Modified Loans (Details) $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2024 USD ($)
Current [Member] |
Performance of Modified Loans [Abstract] |
Amortized cost | $ 863
31-60 Days Past Due [Member] |
Performance of Modified Loans [Abstract] |
Amortized cost | 0
61-90 Days Past Due [Member] |
Performance of Modified Loans [Abstract] |
Amortized cost | 0
Greater Than 90 Days Past Due [Member] |
Performance of Modified Loans [Abstract] |
Amortized cost | 29
Residential [Member] | Current [Member] |
Performance of Modified Loans [Abstract] |
Amortized cost | 863
Residential [Member] | 31-60 Days Past Due [Member] |
Performance of Modified Loans [Abstract] |
Amortized cost | 0
Residential [Member] | 61-90 Days Past Due [Member] |
Performance of Modified Loans [Abstract] |
Amortized cost | 0
Residential [Member] | Greater Than 90 Days Past Due [Member] |
Performance of Modified Loans [Abstract] |
Amortized cost | $ 29

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

X
- Definition Amortized cost of financing receivable modified during period for debtor experiencing financial difficulty. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 42 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-42 Reference 2: 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 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 33 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-33 + Details
Name: | us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancialAssetNotPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=nbtb_FinancingReceivables31To60DaysPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=nbtb_FinancingReceivables61To90DaysPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=nbtb_FinancingReceivablesGreaterThan90DaysPastDueMember
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: |