XML 63 R51.htm IDEA: XBRL DOCUMENT v3.20.2

LEASES - Leased Branch Properties (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease right-of-use asset	$ 8,713	$ 8,713
Less: accumulated amortization	(1,063)	(712)
Operating lease right-of-use-assets, net	$ 7,650	$ 8,001

X

- Definition

Operating Lease, Right-Of-Use Asset, Accumulated Amortization

+ References

No definition available.

+ Details

Name:	chmg_OperatingLeaseRightOfUseAssetAccumulatedAmortization
Namespace Prefix:	chmg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Operating Lease, Right-Of-Use Asset, Gross

+ References

No definition available.

+ Details

Name:	chmg_OperatingLeaseRightOfUseAssetGross
Namespace Prefix:	chmg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- References

No definition available.

+ Details

Name:	us-gaap_LeasesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of lessee's right to use underlying asset under operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

+ Details

Name:	us-gaap_OperatingLeaseRightOfUseAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant