XML 59 R49.htm IDEA: XBRL DOCUMENT
v3.23.2

Allowance for Credit Losses and Credit Quality of Loans, Amortized Cost Basis of Loans Modified to Borrowers Experiencing Financial Difficulty (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2023 | Jun. 30, 2023
Term Extension [Member] |  |
Modified Loans Disaggregated by Class of Financing Receivable and Type of Concession Granted [Abstract] |  |
Amortized cost | $ 199 | $ 242
Combination - Term Extension and Interest Rate Reduction [Member] |  |
Modified Loans Disaggregated by Class of Financing Receivable and Type of Concession Granted [Abstract] |  |
Amortized cost | 171 | 171
Residential [Member] | Term Extension [Member] |  |
Modified Loans Disaggregated by Class of Financing Receivable and Type of Concession Granted [Abstract] |  |
Amortized cost | $ 199 | $ 242
% of total class of financing receivables | 0.009% | 0.011%
Residential [Member] | Combination - Term Extension and Interest Rate Reduction [Member] |  |
Modified Loans Disaggregated by Class of Financing Receivable and Type of Concession Granted [Abstract] |  |
Amortized cost | $ 171 | $ 171
% of total class of financing receivables | 0.008% | 0.008%

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

X
- Definition Percentage of financing receivable modified during period for debtor experiencing financial difficulty to total financing receivables. + 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 + Details
Name: | us-gaap_FinancingReceivableModificationToTotalFinancingReceivablesPercent
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
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_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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: |