XML 75 R59.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Summary of Significant Accounting Policies, Other Financial Instruments (Details) | 12 Months Ended
--- | ---
Dec. 31, 2021
Other Financial Instruments [Abstract] |
Standby letters of credit expiration period | 1 year

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

X
- Definition Represents expiration period of standby letters of credit, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | nbtb_StandbyLettersOfCreditExpirationPeriod
Namespace Prefix: | nbtb_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration