CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($)	10 Months Ended	12 Months Ended
Sep. 30, 2017	Sep. 30, 2018
REVENUES:
Address commissions	$ 74,271	$ 153,406

Address commissions represent discount (sales incentive) on services rendered by the Company and no identifiable benefit is received in exchange for the consideration provided to the charterer.

No definition available.

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