The amount of accrued charter revenue, classified as current.

No definition available.

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

- Definition

The amount of accrued charter revenue liability.

+ References

No definition available.

+ Details

Name:	cmre_AccruedCharterRevenueLiability
Namespace Prefix:	cmre_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents net accrued charter revenue.

+ References

No definition available.

+ Details

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

- Definition

Non-Current portion of revenue earned, but not collected, resulting from charter agreements providing for varying annual charter rates over their terms, which were accounted for on a straight-line basis at their average rates.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of amortization of the time charter assumed, asset.

+ References

No definition available.

+ Details

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

- Definition

The amortization of the time charter assumed, liability.

+ References

No definition available.

+ Details

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

- Definition

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 985
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481283/985-20-50-2

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of voting equity interest acquired in business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
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-Name Accounting Standards Codification
-Section 50
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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 926
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483154/926-20-50-5

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=cmre_CompaniesOwningTritonTitanTalosTaurusAndTheseusMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=cmre_YorkMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=cmre_CompanyOwningCapeArtemisioMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=cmre_CompanyOwningArkadiaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=cmre_DeferredRevenueMember
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Note 12 - Accrued Charter Revenue, Current and Non-current, Unearned Revenue, Current and Non-current and Time Charter Assumed, Current and Non-current (Details Textual) - USD ($) $ in Thousands				6 Months Ended
	Dec. 11, 2023	Mar. 29, 2021	Nov. 12, 2018	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Accrued Charter Revenue, Net				$ (14,608)		$ (16,371)
Accrued Charter Revenue, Current				9,262		11,929
Accrued Charter Revenue, Noncurrent				4,482		2,688
Amortization of Time Charter Assumed, Liability				64	$ 435
Amortization of Assumed Time Charter, Asset				98	$ 305
Time Charter Assumed Asset Position [Member]
Finite-Lived Intangible Assets, Net				171		269
Companies Owning Triton, Titan, Talos, Taurus and Theseus [Member] \| York [Member]
Business Acquisition, Percentage of Voting Interests Acquired			60.00%
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)			7 years 4 months 24 days
Company Owning Cape Artemisio [Member] \| York [Member]
Business Acquisition, Percentage of Voting Interests Acquired		51.00%
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)		4 years 3 months 18 days
Company Owning Arkadia [Member] \| York [Member]
Business Acquisition, Percentage of Voting Interests Acquired	51.00%
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)	2 months 12 days
Deferred Revenue [Member]
Accrued Charter Revenue Liability				$ 28,352		$ 30,988