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 ($)
$ in Thousands
1 Months Ended 12 Months Ended
Sep. 30, 2020
Dec. 31, 2020
Jun. 30, 2021
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  
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
Fair value assets of transfer level 2 to level 1   0 0 0
Fair value assets of transfer level 1 to level 3   0 0 0
Fair value liabilities of transfer level 1 to level 2   0 0 0
Fair value liabilities of transfer level 2 to level 1   0 0 0
Fair value liabilities of transfer level 1 to level 3   $ 0 $ 0 $ 0
Evolv Technologies Holdings, Inc. | 2020 Convertible Notes        
Valuation of Embedded Derivative Liability        
Percentage of conversion 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 $ 1,000