XML 61 R51.htm IDEA: XBRL DOCUMENT v3.23.2

Allowance for Credit Losses and Credit Quality of Loans, Performance of Modified Loans (Details) - ASU 2022-02 [Member] - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2023
Current [Member]
Performance of Modified Loans [Abstract]
Amortized cost	$ 370	$ 413
31-60 Days Past Due [Member]
Performance of Modified Loans [Abstract]
Amortized cost	0	0
61-90 Days Past Due [Member]
Performance of Modified Loans [Abstract]
Amortized cost	0	0
Greater Than 90 Days Past Due [Member]
Performance of Modified Loans [Abstract]
Amortized cost	0	0
Residential [Member] | Current [Member]
Performance of Modified Loans [Abstract]
Amortized cost	370	413
Residential [Member] | 31-60 Days Past Due [Member]
Performance of Modified Loans [Abstract]
Amortized cost	0	0
Residential [Member] | 61-90 Days Past Due [Member]
Performance of Modified Loans [Abstract]
Amortized cost	0	0
Residential [Member] | Greater Than 90 Days Past Due [Member]
Performance of Modified Loans [Abstract]
Amortized cost	$ 0	$ 0

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_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate202202Member
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: