XML 133 R116.htm IDEA: XBRL DOCUMENT
v3.24.0.1

REGULATORY CAPITAL REQUIREMENTS (Details) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($)
Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract] |  |
Net profits period for accessing dividends declarable (years) | 2 years |
Declarable dividends without prior approval for next fiscal year | $ 59,400 |
Total Capital (to Risk Weighted Assets): |  |
Actual | 262,864 | $ 239,478
Tier 1 Capital (to Risk Weighted Assets): |  |
Actual | 239,429 | 219,820
Common Equity Tier 1 Capital (to Risk Weighted Assets): |  |
Actual | 239,429 | 219,820
Tier 1 Capital (to Average Assets): |  |
Actual | $ 239,429 | $ 219,820
Risk Based Ratios [Abstract] |  |
Capital to Risk Weighted Assets | 0.1326 | 0.1257
Tier One Risk Based Capital to Risk Weighted Assets | 0.1208 | 0.1154
Common Equity Tier 1 Capital to Risk Weighted Assets | 12.08% | 11.54%
Leverage Ratios [Abstract] |  |
Tier One Leverage Capital to Average Assets (in hundredths) | 0.0862 | 0.0823
Bank |  |
Total Capital (to Risk Weighted Assets): |  |
Actual | $ 252,783 | $ 230,560
Minimal Capital Adequacy | 158,438 | 152,414
Minimal Capital Adequacy with Capital Buffer | 207,950 | 200,044
To Be Well Capitalized Under Prompt Corrective Action Provisions | 198,048 | 190,518
Tier 1 Capital (to Risk Weighted Assets): |  |
Actual | 229,348 | 210,901
Minimal Capital Adequacy | 118,829 | 114,311
Minimal Capital Adequacy with Capital Buffer | 168,341 | 161,940
To Be Well Capitalized Under Prompt Corrective Action Provisions | 158,438 | 152,414
Common Equity Tier 1 Capital (to Risk Weighted Assets): |  |
Actual | 229,348 | 210,901
Minimal Capital Adequacy | 89,122 | 85,733
Minimal Capital Adequacy with Capital Buffer | 138,634 | 133,363
To Be Well Capitalized Under Prompt Corrective Action Provisions | 128,731 | 123,837
Tier 1 Capital (to Average Assets): |  |
Actual | 229,348 | 210,901
Minimal Capital Adequacy | 111,034 | 106,616
To Be Well Capitalized Under Prompt Corrective Action Provisions | $ 138,792 | $ 133,270
Risk Based Ratios [Abstract] |  |
Capital to Risk Weighted Assets | 0.1276 | 0.1210
Capital Required To Be Adequately Capitalized to Risk Weighted Assets | 0.0800 | 0.0800
Capital Required for Capital Adequacy with Capital Buffer to Risk Weighted Assets | 10.50% | 10.50%
Capital Required To Be Well Capitalized to Risk Weighted Assets | 0.1000 | 0.1000
Tier One Risk Based Capital to Risk Weighted Assets | 0.1158 | 0.1107
Tier One Risk Based Capital Required To Be Adequately Capitalized to Risk Weighted Assets | 0.0600 | 0.0600
Tier One Risk Based Capital Required for Capital Adequacy With Capital Buffer to Risk Weighted Assets | 8.50% | 8.50%
Tier One Risk Based Capital Required To Be Well Capitalized to Risk Weighted Assets | 0.0800 | 0.0800
Common Equity Tier 1 Capital to Risk Weighted Assets | 11.58% | 11.07%
Common Equity Tier 1 Capital Required to be Adequately Capitalized to Risk Weighted Assets | 4.50% | 4.50%
Common Equity Tier One Risk Based Capital Requirement for Capital Adequacy with Capital Buffer to Risk Weighted Assets | 7.00% | 7.00%
Common Equity Tier 1 Capital Required to be Well Capitalized to Risk Weighted Assets | 6.50% | 6.50%
Leverage Ratios [Abstract] |  |
Tier One Leverage Capital to Average Assets (in hundredths) | 0.0826 | 0.0791
Tier One Leverage Capital Required To Be Adequately Capitalized to Average Assets (in hundredths) | 0.0400 | 0.0400
Tier One Leverage Capital Required To Be Well Capitalized to Average Assets (in hundredths) | 0.0500 | 0.0500

X
- Definition Capital Required For Capital Adequacy With Capital Buffer + References No definition available. + Details
Name: | chmg_CapitalRequiredForCapitalAdequacyWithCapitalBuffer
Namespace Prefix: | chmg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Capital Required for Capital Adequacy with Capital Buffer to Risk Weighted Assets + References No definition available. + Details
Name: | chmg_CapitalRequiredforCapitalAdequacywithCapitalBuffertoRiskWeightedAssets
Namespace Prefix: | chmg_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Equity Tier One Risk Based Capital + References No definition available. + Details
Name: | chmg_CommonEquityTierOneRiskBasedCapital
Namespace Prefix: | chmg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Common Equity Tier One Risk Based Capital Required for Capital Adequacy + References No definition available. + Details
Name: | chmg_CommonEquityTierOneRiskBasedCapitalRequiredforCapitalAdequacy
Namespace Prefix: | chmg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Common Equity Tier One Risk Based Capital Required for Capital Adequacy with Capital Buffer + References No definition available. + Details
Name: | chmg_CommonEquityTierOneRiskBasedCapitalRequiredforCapitalAdequacywithCapitalBuffer
Namespace Prefix: | chmg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Common Equity Tier One Risk Based Capital Required to be Well Capitalized + References No definition available. + Details
Name: | chmg_CommonEquityTierOneRiskBasedCapitalRequiredtobeWellCapitalized
Namespace Prefix: | chmg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Common Equity Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets + References No definition available. + Details
Name: | chmg_CommonEquityTierOneRiskBasedCapitalRequiredtobeWellCapitalizedtoRiskWeightedAssets
Namespace Prefix: | chmg_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Equity Tier One Risk Based Capital Requirement for Capital Adequacy to Risk Weighted Assets + References No definition available. + Details
Name: | chmg_CommonEquityTierOneRiskBasedCapitalRequirementforCapitalAdequacytoRiskWeightedAssets
Namespace Prefix: | chmg_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Equity Tier One Risk Based Capital Requirement for Capital Adequacy with Capital Buffer to Risk Weighted Assets + References No definition available. + Details
Name: | chmg_CommonEquityTierOneRiskBasedCapitalRequirementforCapitalAdequacywithCapitalBuffertoRiskWeightedAssets
Namespace Prefix: | chmg_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Equity Tier One Risk Based Capital To Risk Weighted Assets + References No definition available. + Details
Name: | chmg_CommonEquityTierOneRiskBasedCapitalToRiskWeightedAssets
Namespace Prefix: | chmg_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Equity One Tier One Risk Based Capital [Abstract] + References No definition available. + Details
Name: | chmg_EquityOneTierOneRiskBasedCapitalAbstract
Namespace Prefix: | chmg_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period of time over which net profits are accessed for determining dividends in accordance with capital requirements. + References No definition available. + Details
Name: | chmg_NetProfitsPeriodForAccessingDividends
Namespace Prefix: | chmg_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tier One Risk Based Capital Required for Capital Adequacy With Capital Buffer to Risk Weighted Assets + References No definition available. + Details
Name: | chmg_TierOneRiskBasedCapitalRequiredforCapitalAdequacyWithCapitalBuffertoRiskWeightedAssets
Namespace Prefix: | chmg_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier One Risk Based Capital Required for Capital Adequacy with Capital Buffer + References No definition available. + Details
Name: | chmg_TierOneRiskBasedCapitalRequiredforCapitalAdequacywithCapitalBuffer
Namespace Prefix: | chmg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Definition Amount of total capital as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 + Details
Name: | us-gaap_Capital
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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

X
- Definition Amount of minimum total risk-based capital required for capital adequacy as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1B + Details
Name: | us-gaap_CapitalRequiredForCapitalAdequacy
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Ratio of minimum total risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1B + Details
Name: | us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of minimum total risk-based capital categorized as well capitalized as defined by regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 + Details
Name: | us-gaap_CapitalRequiredToBeWellCapitalized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Ratio of minimum total risk-based capital to risk-weighted assets categorized as well capitalized as defined by regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 + Details
Name: | us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio of total risk-based capital to risk-weighted assets as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 + Details
Name: | us-gaap_CapitalToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

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

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

X
- Definition Amount of dividends that can be declared or paid without approval of regulatory agency. + References No definition available. + Details
Name: | us-gaap_StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPaymentsWithoutRegulatoryApproval
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of Tier 1 leverage capital as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 + Details
Name: | us-gaap_TierOneLeverageCapital
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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

X
- Definition Amount of minimum Tier 1 leverage capital required for capital adequacy as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1B + Details
Name: | us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacy
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Ratio of minimum Tier 1 leverage capital to average assets required for capital adequacy as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1B + Details
Name: | us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of minimum Tier 1 leverage capital categorized as well capitalized as defined by regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 + Details
Name: | us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Ratio of minimum Tier 1 leverage capital to average assets categorized as well capitalized as defined by regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 + Details
Name: | us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio of Tier 1 capital to average assets as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 + Details
Name: | us-gaap_TierOneLeverageCapitalToAverageAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of Tier 1 risk-based capital as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 + Details
Name: | us-gaap_TierOneRiskBasedCapital
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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

X
- Definition Amount of minimum Tier 1 risk-based capital required for capital adequacy as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1B + Details
Name: | us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacy
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Ratio of minimum Tier 1 risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1B + Details
Name: | us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of minimum Tier 1 risk-based capital categorized as well capitalized as defined by regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 + Details
Name: | us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Ratio of minimum Tier 1 risk-based capital to risk-weighted assets categorized as well capitalized as defined by regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 + Details
Name: | us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio of Tier 1 risk-based capital to risk-weighted assets as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480696/942-505-50-1 + Details
Name: | us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=srt_SubsidiariesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |