General form of registration statement for all companies including face-amount certificate companies

Fair Value Measurements - Additional Information (Details)

v3.21.2
Fair Value Measurements - Additional Information (Details) - USD ($)
1 Months Ended 2 Months Ended 6 Months Ended 12 Months Ended
Jun. 21, 2021
Jan. 31, 2021
Sep. 30, 2020
Feb. 28, 2021
Jun. 30, 2021
Dec. 31, 2020
Dec. 31, 2020
Mar. 31, 2020
Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                  
Fair value assets of transfer level 1 to level 2         $ 0        
Fair value assets of transfer level 2 to level 1         0        
Fair value assets of transfer level 1 to level 3         0        
Fair value liabilities of transfer level 1 to level 2         0        
Fair value liabilities of transfer level 2 to level 1         0        
Fair value liabilities of transfer level 1 to level 3         0        
Valuation of Embedded Derivative Liability                  
Derivative liability           $ 21,519,000 $ 21,519,000    
Evolv Technologies Holdings, Inc.                  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                  
Fair value assets of transfer level 1 to level 2         0 0 0   $ 0
Fair value assets of transfer level 2 to level 1         0 0 0   0
Fair value assets of transfer level 1 to level 3         0 0 0   0
Fair value liabilities of transfer level 1 to level 2         0 0 0   0
Fair value liabilities of transfer level 2 to level 1         0 0 0   0
Fair value liabilities of transfer level 1 to level 3         0 $ 0 $ 0   $ 0
Valuation of Embedded Derivative Liability                  
Expected dividend yield         $ 0        
Percentage of shares issued to inverstors, conversion price equal           80.00%      
Evolv Technologies Holdings, Inc. | 2020 Convertible Notes                  
Valuation of Embedded Derivative Liability                  
Probability of completing specified financing     100.00%            
Percentage of coversion price per share of securities by investors     80.00%            
Percentage of conversion option was deemed at fair value of capital stock     20.00%       20.00%    
Fair value of the embedded derivative at issuance     $ 1,000,000.0     $ 1,000,000.0 $ 1,000,000.0    
Evolv Technologies Holdings, Inc. | 2021 Convertible Notes                  
Valuation of Embedded Derivative Liability                  
Probability of completing specified financing               100.00%  
Percentage of coversion price per share of securities by investors   80.00%              
Percentage of conversion option was deemed at fair value of capital stock   20.00%              
Fair value of the embedded derivative at issuance   $ 7,000,000.0              
Embedded derivative liability               $ 9,200,000  
Percentage of shares issued to inverstors, conversion price equal       80.00%          
Number of shares issued upon conversion of debt 1,000,000                
Derivative liability $ 9,800,000