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- References

No definition available.

Name:	cbu_TimeDepositsMaturities250000OrMoreAbstract
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he amount maturities of domestic and foreign time deposits (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $250,000 or more, after five years from the balance sheet date.

No definition available.

Name:	cbu_TimeDepositsMaturities250000OrMoreAfterYearFive
Namespace Prefix:	cbu_
Data Type:	xbrli:monetaryItemType
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The amount of maturities domestic and foreign time deposits (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $250,000 or more, for next twelve months from the balance sheet date.

No definition available.

Name:	cbu_TimeDepositsMaturities250000OrMoreNextTwelveMonths
Namespace Prefix:	cbu_
Data Type:	xbrli:monetaryItemType
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The amount maturities of domestic and foreign time deposits (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $250,000 or more, for year five from the balance sheet date.

No definition available.

Name:	cbu_TimeDepositsMaturities250000OrMoreYearFive
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Data Type:	xbrli:monetaryItemType
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No definition available.

Name:	cbu_TimeDepositsMaturities250000OrMoreYearFour
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

The amount of maturities of domestic and foreign time deposits (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $250,000 or more, for year three from the balance sheet date.

No definition available.

Name:	cbu_TimeDepositsMaturities250000OrMoreYearThree
Namespace Prefix:	cbu_
Data Type:	xbrli:monetaryItemType
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No definition available.

Name:	cbu_TimeDepositsMaturities250000OrMoreYearTwo
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of time deposits maturing after the fifth fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

Name:	us-gaap_TimeDepositMaturitiesAfterYearFive
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Amount of time deposits maturing in the fifth fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of time deposits maturing in the fourth fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of time deposits maturing in the next fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Name:	us-gaap_TimeDepositMaturitiesYearOne
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Amount of time deposits maturing in the third fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Period Type:	instant

Amount of time deposits maturing in the second fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Name:	us-gaap_TimeDepositMaturitiesYearTwo
Namespace Prefix:	us-gaap_
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Amount of time deposit liabilities, including certificates of deposit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 405
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=116652737&loc=d3e64164-112818

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.12)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- References

No definition available.