Registration of securities issued in business combination transactions

COMMITMENTS AND CONTINGENCIES (FY) (Details)

v3.21.4
COMMITMENTS AND CONTINGENCIES (FY) (Details)
3 Months Ended 9 Months Ended 12 Months Ended
Mar. 31, 2020
USD ($)
Sep. 30, 2021
USD ($)
Dec. 31, 2020
USD ($)
$ / shares
Oct. 16, 2020
USD ($)
Sep. 30, 2020
USD ($)
Aug. 13, 2020
item
Loss Contingencies [Line Items]            
Maximum number of demands for registration of securities | item           3
Deferred underwriting fee payable   $ 8,050,000 $ 8,050,000   $ 8,050,000  
Aggregate purchase price $ 25,000   $ 25,000      
If there are only two advisors            
Loss Contingencies [Line Items]            
Cash fee payable, percentage       33.33%    
Underwriting Agreement            
Loss Contingencies [Line Items]            
Deferred fee per unit | $ / shares     $ 0.35      
Deferred underwriting fee payable     $ 8,050,000      
Forward Purchase Agreement            
Loss Contingencies [Line Items]            
Aggregate purchase price   $ 100,000,000.0 $ 100,000,000.0      
Commitment fee (in percent)   2.00% 2.00%      
Open Market or Privately Negotiated Transactions            
Loss Contingencies [Line Items]            
Aggregate purchase price   $ 85,000,000.0 $ 85,000,000.0      
Right of First Refusal            
Loss Contingencies [Line Items]            
Percentage of outstanding common stock of the post-business combination   5.00% 5.00%      
Maximum duration (in years)   3 years 3 years      
Advisory Agreement            
Loss Contingencies [Line Items]            
Cash fee payable for financial advisory services       $ 7,350,000    
Cash fee payable, percentage       50.00%    
Threshold minimum percentage of gross proceeds of the total Securities sold in the Acquisition payable as cash fee       2.00%    
Advisory services fee incurred     $ 0      
Advisory Agreement | If there are only two advisors            
Loss Contingencies [Line Items]            
Percentage of gross proceeds of the total Securities sold in the Acquisition payable as cash fee       4.50%    
Advisory Agreement | If there are only three advisors            
Loss Contingencies [Line Items]            
Percentage of gross proceeds of the total Securities sold in the Acquisition payable as cash fee       6.00%    
Maximum            
Loss Contingencies [Line Items]            
Commitment carrying costs     1,000,000.0      
Maximum | Forward Purchase Agreement            
Loss Contingencies [Line Items]            
Commitment carrying costs   $ 1,000,000.0 100,000,000.0      
Additional financing amount   $ 400,000,000 $ 400,000,000