XML 80 R88.htm IDEA: XBRL DOCUMENT
v3.20.1

Repurchase Agreements (Details) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2018 USD ($)
Disclosure of Repurchase Agreements [Abstract] |
Average balance during the year | $ 1,412
Average interest rate during the year | 0.05%
Maximum month end balance during the year | $ 7,148

X
- Definition The calculated average balance during the year. + References No definition available. + Details
Name: | cofs_AverageBalanceSecuritiesSold
Namespace Prefix: | cofs_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The calculated average interest rate paid during the year. + References No definition available. + Details
Name: | cofs_AverageInterestRatePaidDuringYear
Namespace Prefix: | cofs_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The maximum month end balance of securities sold under repurchase agreements. + References No definition available. + Details
Name: | cofs_MaximumMonthEndBalance
Namespace Prefix: | cofs_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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