Name:	cmre_GainLossOnAssetsHeldForSale
Namespace Prefix:	cmre_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The difference between the sale price or salvage price and the book value of a vessel that was sold during the reporting period. This element refers to the gain (loss).

No definition available.

Name:	cmre_GainLossOnSaleVessels
Namespace Prefix:	cmre_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The number of vessels provided as collaterals to secure loans as of the reporting period.

No definition available.

Name:	cmre_NumberOfVesselsProvidedAsCollateralsToSecureLoans
Namespace Prefix:	cmre_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

The price for the acquisition of a vessel or group of vessels.

No definition available.

Name:	cmre_PriceVessels
Namespace Prefix:	cmre_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

Name:	cmre_VesselHeldForSale
Namespace Prefix:	cmre_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The sale price for the disposal of a vessel or group of vessels.

No definition available.

Name:	cmre_VesselsDisposalPrice
Namespace Prefix:	cmre_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=cmre_MSCChallengerDisposalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=cmre_VesselsAcquisitionDuringReportingPeriodMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=cmre_KonstantinaDisposalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=cmre_VesselsNetAdditionalInformationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=cmre_KarmenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: