Class of Warrant or Right, Remaining Term

No definition available.

Name:	mgen_ClassofWarrantorRightRemainingTerm
Namespace Prefix:	mgen_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(2))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=mgen_LiabilityClassifiedWarrantsIssuedApril2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=mgen_EquityclassifiedWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=mgen_EquityclassifiedWarrantsIssuedFebruary2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=mgen_EquityclassifiedWarrantsIssuedNovember2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=mgen_EquityclassifiedWarrantsAcquiredFebruary2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

WARRANTS - Stock Warrants Outstanding (Details) - $ / shares	3 Months Ended
	Mar. 31, 2020	Feb. 29, 2020	Dec. 31, 2019	Dec. 31, 2017
Class of Warrant or Right [Line Items]
Number of Underlying Shares (in shares)	7,535,815		46,522
Weighted average exercise price (in usd per share)	$ 1.13		$ 17.93
Issued April 2017
Class of Warrant or Right [Line Items]
Number of Underlying Shares (in shares)	11,718		11,718
Weighted average exercise price (in usd per share)	$ 8.53
Remaining Contractual Life at March 31, 2020 (No. Years)	5 years 29 days
Equity-classified warrants
Class of Warrant or Right [Line Items]
Number of Underlying Shares (in shares)	7,524,097		34,804
Weighted average exercise price (in usd per share)	$ 1.12
Issued February 2020 (2)
Class of Warrant or Right [Line Items]
Number of Underlying Shares (in shares)	7,500,000	7,500,000	0
Weighted average exercise price (in usd per share)	$ 1.10	$ 1.10
Remaining Contractual Life at March 31, 2020 (No. Years)	4 years 10 months 10 days
Issued November 2017
Class of Warrant or Right [Line Items]
Number of Underlying Shares (in shares)	24,097		24,097
Weighted average exercise price (in usd per share)	$ 7.15
Remaining Contractual Life at March 31, 2020 (No. Years)	4 years 7 months 17 days
Acquired February 2017
Class of Warrant or Right [Line Items]
Number of Underlying Shares (in shares)	0		10,707	13,534
Weighted average exercise price (in usd per share)	$ 0.00			$ 52.50