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

Amount of amortization expense for lease with finite life acquired as part of real property acquisition at above market lease rate expected to be recognized in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

No definition available.

Name:	ctrm_AboveMarketLeaseAmortizationYearTwo
Namespace Prefix:	ctrm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount after accumulated amortization of the identifiable intangible asset established upon acquisition based on a favorable difference between the terms of an acquired lease and the current market terms for that lease at the acquisition date.

No definition available.

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

Amount of non-cash amortization of intangible asset (liability) for above and below market leases.

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

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

- References

No definition available.

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

Amount after amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life.

No definition available.