Significant Accounting Policies, Disaggregation of Revenue (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2021	Dec. 31, 2020
Disaggregation by Revenue Source [Abstract]
Accounts receivable trade, net	$ 390	$ 801
Current portion of deferred revenue	6,231	4,510
Deferred revenue recognized	2,515
ASC 606 [Member]
Disaggregation by Revenue Source [Abstract]
Current portion of deferred revenue	458
ASC 842 [Member]
Disaggregation by Revenue Source [Abstract]
Current portion of deferred revenue	5,773
Spot Charter [Member]
Disaggregation by Revenue Source [Abstract]
Accounts receivable trade, net	362	801
Time Charter [Member]
Disaggregation by Revenue Source [Abstract]
Accounts receivable trade, net	$ 28	$ 0

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=124098289&loc=d3e6676-107765

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=124259787&loc=d3e4531-111522

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