XML 54 R42.htm IDEA: XBRL DOCUMENT
v3.10.0.1

INVESTMENT SECURITIES, Investment Securities in a Continuous Unrealized Loss Position (Details) $ in Thousands | Jun. 30, 2018 USD ($) Position | Dec. 31, 2017 USD ($) Position
--- | --- | ---
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract] |  |
Less than 12 months | Position | 469 | 249
12 months or longer | Position | 89 | 56
Total | Position | 558 | 305
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 2,312,116 | $ 991,521
12 months or longer | 112,099 | 75,713
Total | 2,424,215 | 1,067,234
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract] |  |
Less than 12 months | 37,815 | 7,231
12 months or longer | 5,208 | 2,330
Total | $ 43,023 | $ 9,561
U.S. Treasury and Agency Securities [Member] |  |
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract] |  |
Less than 12 months | Position | 77 | 44
12 months or longer | Position | 3 | 0
Total | Position | 80 | 44
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 1,924,896 | $ 699,709
12 months or longer | 14,945 | 0
Total | 1,939,841 | 699,709
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract] |  |
Less than 12 months | 28,567 | 4,838
12 months or longer | 64 | 0
Total | $ 28,631 | $ 4,838
Obligations of State and Political Subdivisions [Member] |  |
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract] |  |
Less than 12 months | Position | 224 | 45
12 months or longer | Position | 0 | 0
Total | Position | 224 | 45
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 111,946 | $ 23,432
12 months or longer | 0 | 0
Total | 111,946 | 23,432
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract] |  |
Less than 12 months | 1,440 | 57
12 months or longer | 0 | 0
Total | $ 1,440 | $ 57
Government Agency Mortgage-Backed Securities [Member] |  |
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract] |  |
Less than 12 months | Position | 135 | 120
12 months or longer | Position | 77 | 55
Total | Position | 212 | 175
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 213,903 | $ 185,716
12 months or longer | 85,735 | 75,712
Total | 299,638 | 261,428
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract] |  |
Less than 12 months | 5,885 | 1,433
12 months or longer | 4,861 | 2,330
Total | $ 10,746 | $ 3,763
Corporate Debt Securities [Member] |  |
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract] |  |
Less than 12 months | Position | 1 | 1
12 months or longer | Position | 0 | 0
Total | Position | 1 | 1
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 2,563 | $ 2,623
12 months or longer | 0 | 0
Total | 2,563 | 2,623
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract] |  |
Less than 12 months | 55 | 25
12 months or longer | 0 | 0
Total | $ 55 | $ 25
Government Agency Collateralized Mortgage Obligations [Member] |  |
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract] |  |
Less than 12 months | Position | 32 | 39
12 months or longer | Position | 9 | 1
Total | Position | 41 | 40
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 58,808 | $ 80,041
12 months or longer | 11,419 | 1
Total | 70,227 | 80,042
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract] |  |
Less than 12 months | 1,868 | 878
12 months or longer | 283 | 0
Total | $ 2,151 | $ 878

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

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

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

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer. + References No definition available. + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months. + References No definition available. + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=cbu_GovernmentAgencyCollateralizedMortgageObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |