No definition available.

Name:	nmmc_ProposedPublicOfferingOfUnitsAbstract
Namespace Prefix:	nmmc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of new units issued during the period. Each unit consists of one share of Class A common stock and one-half of one warrant.

+ References

No definition available.

+ Details

Name:	nmmc_UnitsIssuedDuringPeriodSharesNewIssues
Namespace Prefix:	nmmc_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of securities into which each unit may be converted. For example, but not limited to, each unit may be converted into two shares of common stock.

+ References

No definition available.

+ Details

Name:	nmmc_UnitsNumberOfSecuritiesCalledByUnits
Namespace Prefix:	nmmc_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21475-112644

+ Details

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

- Definition

Number of securities into which each warrant or right may be converted. For example, but not limited to, each warrant may be converted into two shares.

+ References

No definition available.

+ Details

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

- Definition

Per share or per unit amount of equity securities issued.

+ References

No definition available.

+ Details

Name:	us-gaap_SharesIssuedPricePerShare
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Details

Name:	us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_IPOMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_OverAllotmentOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

PUBLIC OFFERING (Q3) (Details) - $ / shares		3 Months Ended
PUBLIC OFFERING (Q3) (Details) - $ / shares	Sep. 22, 2020	Sep. 30, 2020	Sep. 30, 2021	Dec. 31, 2020
Public Warrants [Member]
Proposed Public Offering [Abstract]
Number of securities to be called by each unit (in shares)			0.5
Class A Common Stock [Member]
Proposed Public Offering [Abstract]
Number of securities to be called by each unit (in shares)	1		1
Initial Public Offering [Member]
Proposed Public Offering [Abstract]
Units issued (in shares)		13,225,000
Initial Public Offering [Member] \| Public Shares [Member]
Proposed Public Offering [Abstract]
Units issued (in shares)	13,225,000
Unit price (in dollars per share)	$ 10.00
Initial Public Offering [Member] \| Public Warrants [Member]
Proposed Public Offering [Abstract]
Number of securities to be called by each unit (in shares)	0.5
Warrants exercise price (in dollars per share)	$ 11.50
Initial Public Offering [Member] \| Class A Common Stock [Member]
Proposed Public Offering [Abstract]
Number of securities to be called by each unit (in shares)	1			1
Number of securities called by each warrant (in shares)	1			1
Over-Allotment Option [Member] \| Public Shares [Member]
Proposed Public Offering [Abstract]
Units issued (in shares)	1,725,000
Unit price (in dollars per share)	$ 10.00