XML 38 R61.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Allowance for Loan Losses and Credit Quality of Loans, Troubled Debt Restructurings (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2014 Contract | Dec. 31, 2013 Contract
Commercial Loans [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of contracts |  | 4 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_CommercialPortfolioSegmentMember
Pre-modification outstanding recorded investment |  | $ 7.0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_CommercialPortfolioSegmentMember
Number of contracts, subsequent default |  | 1 us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_CommercialPortfolioSegmentMember
Outstanding recorded investment, subsequent default |  | 0.9 us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_CommercialPortfolioSegmentMember
Home Equity [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of contracts | 9 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_HomeEquityMember | 23 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_HomeEquityMember
Pre-modification outstanding recorded investment | 0.3 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_HomeEquityMember | 1.0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_HomeEquityMember
Number of contracts, subsequent default | 1 us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_HomeEquityMember | 8 us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_HomeEquityMember
Outstanding recorded investment, subsequent default | 0.1 us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_HomeEquityMember | 0.4 us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_HomeEquityMember
Residential Real Estate Mortgages [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of contracts | 27 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_ResidentialPortfolioSegmentMember | 6 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_ResidentialPortfolioSegmentMember
Pre-modification outstanding recorded investment | 2.7 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_ResidentialPortfolioSegmentMember | 0.5 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_ResidentialPortfolioSegmentMember
Number of contracts, subsequent default | 6 us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_ResidentialPortfolioSegmentMember |
Outstanding recorded investment, subsequent default | 0.4 us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_ResidentialPortfolioSegmentMember |
Business Banking [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of contracts | 3 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = nbtb_SmallBusinessFinancingReceivableMember |
Pre-modification outstanding recorded investment | 0.9 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = nbtb_SmallBusinessFinancingReceivableMember |
Indirect Consumer Loan [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of contracts | 1 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_ConsumerOtherFinancingReceivableMember |
Pre-modification outstanding recorded investment | 0.1 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_ConsumerOtherFinancingReceivableMember |
Number of contracts, subsequent default | 1 us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_ConsumerOtherFinancingReceivableMember |
Outstanding recorded investment, subsequent default | 0.1 us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = us-gaap_ConsumerOtherFinancingReceivableMember |
Direct Consumer Loan [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of contracts | 47 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = nbtb_DirectConsumerLoanMember |
Pre-modification outstanding recorded investment | 3.0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = nbtb_DirectConsumerLoanMember |
Number of contracts, subsequent default | 5 us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = nbtb_DirectConsumerLoanMember |
Outstanding recorded investment, subsequent default | $ 0.2 us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1 / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = nbtb_DirectConsumerLoanMember |

X
- Details
Name: | us-gaap_FinancingReceivableModificationsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of financing receivables that have been modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Pre-modification amount of investment in financing receivables modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 34 -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953682-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 34 -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953682-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=nbtb_DirectConsumerLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=nbtb_SmallBusinessFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=us-gaap_ConsumerOtherFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=us-gaap_HomeEquityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |