RELATED PARTY TRANSACTIONS, Founder Shares (Details)		6 Months Ended	12 Months Ended
RELATED PARTY TRANSACTIONS, Founder Shares (Details)	Jul. 14, 2020 USD ($) shares	Dec. 31, 2020 USD ($)	Dec. 31, 2021 USD ($) $ / shares	Sep. 22, 2020 shares	Sep. 17, 2020 $ / shares	Jul. 13, 2020 shares
Founder Shares [Abstract]
Proceeds from issuance of Class B common stock to Sponsor \| $		$ 25,000	$ 0
Stock conversion basis at time of business combination			1
Share price (in dollars per share) \| $ / shares					$ 10.00
Class A Common Stock [Member]
Founder Shares [Abstract]
Number of trading days			30 days
Trading day threshold period			20 days
Class A Common Stock [Member] \| Minimum [Member]
Founder Shares [Abstract]
Share price (in dollars per share) \| $ / shares			$ 18.00
Founder Shares [Member] \| Sponsor [Member] \| Class A Common Stock [Member]
Founder Shares [Abstract]
Stock conversion basis at time of business combination			1
Holding period for transfer, assignment or sale of Founder Shares			1 year
Number of trading days			20 days
Trading day threshold period			30 days
Founder Shares [Member] \| Sponsor [Member] \| Class A Common Stock [Member] \| Minimum [Member]
Founder Shares [Abstract]
Share price (in dollars per share) \| $ / shares			$ 12.00
Threshold period after initial Business Combination			150 days
Founder Shares [Member] \| Sponsor [Member] \| Class B Common Stock [Member]
Founder Shares [Abstract]
Shares issued (in shares) \| shares	3,306,250
Proceeds from issuance of Class B common stock to Sponsor \| $	$ 25,000
Ownership interest, as converted percentage			20.00%
Number of shares no longer subject to forfeiture (in shares) \| shares				431,250
Founder Shares [Member] \| Sponsor [Member] \| Class B Common Stock [Member] \| Maximum [Member]
Founder Shares [Abstract]
Number of shares subject to forfeiture (in shares) \| shares						431,250

North Mountain Merger Corp. 10-K