Note 25 - Earnings Per Share (Details Textual) - shares	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement Line Items [Line Items]
Antidilutive options excluded from computation of earnings per share, amount	32,771	37,302	18,378
Options out of the money [member]
Statement Line Items [Line Items]
Antidilutive options excluded from computation of earnings per share, amount	18,000	18,000

Number of options that could potentially dilute basic earnings per share in the future that were not included in the computation of diluted earnings per share because to do so would increase or decrease earnings per share for the periods presented.

No definition available.

Name:	cmcl_AntidilutiveOptionsExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	cmcl_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration