Name:	ctrm_RelatedPartyTransactionCommissionRate
Namespace Prefix:	ctrm_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

A commission charged by a related party in connection with each vessel sale and purchase transaction.

No definition available.

Name:	ctrm_RelatedPartyTransactionCommissionRateOnEachVesselSaleAndPurchaseTransaction
Namespace Prefix:	ctrm_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Fixed daily fee charged by a related party to provide a wide range of shipping services such as crew management, technical management, operational employment management, insurance arrangements, provisioning, bunkering, accounting services, general administration and audit support.

No definition available.

Name:	ctrm_RelatedPartyTransactionFixedDailyFee
Namespace Prefix:	ctrm_
Data Type:	srt-types:perUnitItemType
Balance Type:	na
Period Type:	duration

Recovery fee multiplier applied to the total amount of the flat management fee calculated on an annual basis under an agreement with a related party.

No definition available.

Name:	ctrm_RelatedPartyTransactionManagementRecoveryFeeMultiplier
Namespace Prefix:	ctrm_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

Termination fee multiplier applied to the total amount of the flat management fee and the per vessel management fee calculated on an annual basis under an agreement with a related party.

No definition available.

Name:	ctrm_RelatedPartyTransactionManagementTerminationFeeMultiplier
Namespace Prefix:	ctrm_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

Fixed quarterly fee charged by a related party to provide a shipping related administrative services.

No definition available.

Name:	ctrm_RelatedPartyTransactionQuarterlyManagementFee
Namespace Prefix:	ctrm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Term of related party agreement renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

No definition available.

Name:	ctrm_RelatedPartyTransactionRenewalTermOfAgreement
Namespace Prefix:	ctrm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Term of related party agreement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

No definition available.

Name:	ctrm_RelatedPartyTransactionTermOfAgreement
Namespace Prefix:	ctrm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Amount of gain (loss) on sale or disposal of property, plant and equipment assets, excluding oil and gas property and timber property.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 5
-URI https://asc.fasb.org/extlink&oid=126905981&loc=d3e2443-110228

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230

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

- References

No definition available.

Name:	us-gaap_GainLossOnSaleOfPropertyPlantEquipmentAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

Name:	us-gaap_RelatedPartyTransactionDueFromToRelatedPartyCurrentAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=ctrm_CastorShipsSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RelatedPartyTransactionAxis=ctrm_ManagementAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RelatedPartyTransactionAxis=ctrm_CommercialShipmanagementAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

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

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=ctrm_PavimarSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: