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

Summary of Significant Accounting Policies - Disaggregated revenue (Details)

v3.21.2
Summary of Significant Accounting Policies - Disaggregated revenue (Details) - USD ($)
 3 Months Ended 5 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Jun. 30, 2020
Jun. 30, 2021
Jun. 30, 2020
Dec. 31, 2020
Dec. 31, 2019
Disaggregation of Revenue [Line Items]              
Total revenue $ 0 $ 0 $ 0 $ 0      
Evolv Technologies Holdings, Inc.              
Disaggregation of Revenue [Line Items]              
Total revenue 4,480,000 649,000   8,479,000 $ 1,289,000 $ 4,785,000 $ 5,846,000
Maintenance revenue included in subscription revenue 400,000 100,000   700,000 300,000 600,000 300,000
Evolv Technologies Holdings, Inc. | Product revenue              
Disaggregation of Revenue [Line Items]              
Total revenue 2,452,000 17,000   4,954,000 73,000 1,279,000 4,192,000
Evolv Technologies Holdings, Inc. | Subscription revenue              
Disaggregation of Revenue [Line Items]              
Total revenue 1,513,000 490,000   2,813,000 949,000 2,637,000 1,096,000
Evolv Technologies Holdings, Inc. | Service revenue              
Disaggregation of Revenue [Line Items]              
Total revenue           350,000 136,000
Evolv Technologies Holdings, Inc. | Maintenance revenue              
Disaggregation of Revenue [Line Items]              
Total revenue $ 224,000 $ 141,000   $ 356,000 $ 262,000 $ 519,000 $ 422,000