The number of vessels to be acquired by the entity.

No definition available.

Name:	ctrm_NumberOfVesselsToBeAcquired
Namespace Prefix:	ctrm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Purchase price of long-lived, physical asset used in the normal conduct of business and not intended for resale.

+ References

No definition available.

+ Details

Name:	ctrm_PropertyPlantAndEquipmentPurchasePrice
Namespace Prefix:	ctrm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The gross daily hire rate for the vessel under the time charter contract.

+ References

No definition available.

+ Details

Name:	ctrm_TimeCharterContractGrossDailyHireRate
Namespace Prefix:	ctrm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percentage of profits above the minimum gross daily hire rate shared with the charterer of the vessel under the time charter contract based on a predetermined formula.

+ References

No definition available.

+ Details

Name:	ctrm_TimeCharterContractProfitSharingPercentage
Namespace Prefix:	ctrm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Term of time charter contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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

- Definition

Term of time charter contract extension that can be executed at the option of the charterer,in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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

- Definition

Amount of acquisition of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentAdditions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=ctrm_AframaxLongRange2TankerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

Subsequent Events, Vessel Acquisitions (Details) - Subsequent Event [Member]		1 Months Ended	2 Months Ended
	Feb. 05, 2021 USD ($) Vessel	Mar. 02, 2021 USD ($)	Mar. 18, 2021 USD ($)	Mar. 17, 2021 USD ($)	Mar. 11, 2021 USD ($)	Mar. 09, 2021 USD ($)	Feb. 18, 2021 USD ($)
Magic Orion [Member]
Vessel Acquisitions [Abstract]
Purchase price of delivered vessel				$ 17,500,000
Magic Venus [Member]
Vessel Acquisitions [Abstract]
Purchase price of delivered vessel		$ 15,850,000
Magic Argo [Member]
Vessel Acquisitions [Abstract]
Purchase price of delivered vessel			$ 14,500,000
Aframax LR2 Tankers [Member]
Vessel Acquisitions [Abstract]
Number of vessels to be acquired \| Vessel	2
Purchase price of vessels	$ 27,200,000
Term of time charter contract	1 year
Gross daily hire rate	$ 15,000
Profit sharing percentage	50.00%
Term of time charter contract extension	1 year
Kamsarmax Vessel [Member]
Vessel Acquisitions [Abstract]
Purchase price of vessels					$ 16,900,000	$ 15,500,000	$ 14,800,000