XML 68 R56.htm IDEA: XBRL DOCUMENT
v3.5.0.2

SUBSEQUENT EVENT (Details) - Forecast | 12 Months Ended
--- | ---
Dec. 31, 2017
Subsequent Event [Line Items] |
Employer beginning contribution, percent of employees' gross pay | 3.00%
Employer matching contribution, percent of match | 50.00%
Employer matching contribution, percent of employees' gross pay | 6.00%

X
- Definition Defined Contribution Plan, Employer Beginning Contribution, Percent of Employees' Gross Pay + References No definition available. + Details
Name: | chmg_DefinedContributionPlanEmployerBeginningContributionPercentofEmployeesGrossPay
Namespace Prefix: | chmg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage employer matches of the employee's percentage contribution matched. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. + References No definition available. + Details
Name: | us-gaap_SubsequentEventLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |