XML 73 R62.htm IDEA: XBRL DOCUMENT v3.25.3

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		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Term Extension [Member]
Modified Loans Disaggregated by Class of Financing Receivable and Type of Concession Granted [Abstract]
Amortized cost	$ 75	$ 576	$ 958	$ 1,054
Combination - Term Extension and Interest Rate Reduction [Member]
Modified Loans Disaggregated by Class of Financing Receivable and Type of Concession Granted [Abstract]
Amortized cost		254	28	284
Residential [Member] | Term Extension [Member]
Modified Loans Disaggregated by Class of Financing Receivable and Type of Concession Granted [Abstract]
Amortized cost	$ 75	$ 576	$ 958	$ 1,054
% of total class of financing receivables	0.002%	0.022%	0.03%	0.04%
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		$ 254	$ 28	$ 284
% of total class of financing receivables		0.01%	0.001%	0.011%

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/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 2: 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

+ 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/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 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-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

Reference 3: 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

+ 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: