Condensed Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (Parentheticals) - shares shares in Thousands	3 Months Ended	9 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Dividend reinvestment plan and restricted award forfeited and expired (in shares)		30		305

The number of dividend reinvestment plan shares associated with forfeited restricted stock awards retired to treasury.

No definition available.

Name:	cbkm_StockIssuedDuringPeriodSharesDividendReinvestmentPlanAndRestrictedAwardForfeitedAndExpired
Namespace Prefix:	cbkm_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration