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PENSION PLAN AND OTHER BENEFIT PLANS - Additional Information (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Defined Contribution Profit Sharing, Savings and Investment Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Chemung common stock included in defined contribution plan assets (in shares) | 169,398 | 170,714 | 178,113
Total expense | $ 639 | $ 620 | $ 521
Defined Contribution Supplemental Executive Retirement Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Balance in the plan | 772 | 550 |
Total expense | $ 231 | $ 213 | $ 155

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- Definition For a defined contribution plan, the number of sponsoring entity common stock shares included in plan assets. + References No definition available. + Details
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Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

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- Definition Refers to the balance of a defined contribution plan outstanding as of the balance sheet date. + References No definition available. + Details
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Namespace Prefix: | chmg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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Balance Type: | na
Period Type: | duration

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- Definition The amount of the cost recognized during the period for defined contribution plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
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- Details
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- Details
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Data Type: | na
Balance Type: |
Period Type: |