The amount of accrued charter revenue, classified as current.

No definition available.

Name:	cmre_AccruedCharterRevenueCurrent
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

Name:	cmre_AccruedCharterRevenueNet
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

Name:	cmre_AccruedCharterRevenueNoncurrent
Namespace Prefix:	cmre_
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

Name:	cmre_AmortizationOfAssumedTimeCharterAsset
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

Name:	cmre_AmortizationOfTimeCharterAssumedLiability
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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

+ Details

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

- Definition

Percentage of voting equity interests acquired at the acquisition date in the business combination.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ Details

Name:	us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired
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/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 926
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=120154696&loc=d3e54445-107959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

+ Details

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

- Details

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

- Details

Name:	us-gaap_BalanceSheetLocationAxis=cmre_DeferredRevenueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 13 - 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			12 Months Ended
	Mar. 29, 2021	Nov. 12, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accrued Charter Revenue, Net			$ (22,980)	$ (34,284)
Accrued Charter Revenue, Current			7,361
Accrued Charter Revenue, Noncurrent			8,183	0
Amortization of Time Charter Assumed, Liability			621	0
Amortization of Assumed Time Charter, Asset			(424)	192	$ 191
York [Member]
Finite-Lived Intangible Assets, Net, Ending Balance			865	$ 1,030
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
Deferred Revenue [Member]
Accrued Charter Revenue Liability			$ (38,524)