Note 13 - Commitments and Contingencies - Schedule of Capital Commitments (Details) $ in Billions	6 Months Ended
Jun. 30, 2026 USD ($)
2027	$ 0.4
2028	0.5
2029	0.6
2030	0.3
Total	$ 1.8

The minimum amount the entity agreed to spend under the long-term purchase commitment to be paid in the fourth fiscal year.

No definition available.

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

The minimum amount the entity agreed to spend under the long-term purchase commitment to be paid in the next fiscal year.

No definition available.

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

The minimum amount the entity agreed to spend under the long-term purchase commitment to be paid in the third fiscal year.

No definition available.

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

The minimum amount the entity agreed to spend under the long-term purchase commitment to be paid in the second fiscal year.

No definition available.

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

The minimum amount the entity agreed to spend under the long-term purchase commitment.

No definition available.

Name:	us-gaap_LongTermPurchaseCommitmentAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration