Adjusted total shares of common stock of combined company.

No definition available.

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- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

+ References

+ Details

Name:	us-gaap_CommonStockSharesIssued
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Data Type:	xbrli:sharesItemType
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- Definition

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644

+ Details

Name:	us-gaap_CommonStockSharesOutstanding
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Data Type:	xbrli:sharesItemType
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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_TypeOfArrangementAxis=MRNA_MergerAgreementMember
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Organization and Business Operations - Schedule Merger Agreement Based On Common Stock Outstanding (Details) - shares	Mar. 31, 2017	Dec. 31, 2016	Nov. 15, 2016	Dec. 31, 2015
Shares of Marina common stock outstanding as of November 15, 2016	89,771,379	89,771,379		58,392,827
Shares of Marina common stock issued to IThena upon closing of transaction	97,099,877	89,771,379		58,392,827
Merger Agreement [Member]
Shares of Marina common stock outstanding as of November 15, 2016			31,378,551
Divided by the percentage of Marina ownership of combined company			35.00%
Adjusted total shares of common stock of combined company			89,771,379
Multiplied by the assumed percentage of IThena ownership of combined company			65.00%
Shares of Marina common stock issued to IThena upon closing of transaction			58,392,828