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

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)

v3.21.4
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)
 1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
May 30, 2020
USD ($)
Mar. 31, 2021
USD ($)
Sep. 30, 2021
USD ($)
Sep. 30, 2020
USD ($)
Dec. 31, 2020
USD ($)
shares
Dec. 31, 2019
USD ($)
Feb. 16, 2021
USD ($)
Apr. 30, 2020
USD ($)
Dec. 31, 2018
USD ($)
Summary of Significant Accounting Policies [Line Items]                  
Unrecognized tax benefits         $ 2,373,000 $ 1,438,000     $ 586,000
Taxes on income     $ 829,000 $ 899,000 1,200,000 902,000      
Goodwill impairment     0 0          
Intangible asset impairment     $ 0 $ 0          
Severance costs         $ 600,000 $ 579,000      
Ad serving services         96.50% 96.90%      
Product Concentration Risk | Revenue Benchmark | Ad Services                  
Summary of Significant Accounting Policies [Line Items]                  
Concentration risk, percentage     93.80% 97.00%          
Product Concentration Risk | Revenue Benchmark | Creative Services                  
Summary of Significant Accounting Policies [Line Items]                  
Concentration risk, percentage     4.80% 2.30%          
Customer Concentration Risk | Revenue Benchmark | Two Customers                  
Summary of Significant Accounting Policies [Line Items]                  
Concentration risk, percentage         18.00% 21.00%      
Software and Software Development Costs                  
Summary of Significant Accounting Policies [Line Items]                  
Useful lives (in years)     3 years            
Capitalization cost     $ 1,049,000            
Employee Severance                  
Summary of Significant Accounting Policies [Line Items]                  
Number of employee deposit, percent         8.33%        
Postemployment Retirement Benefits                  
Summary of Significant Accounting Policies [Line Items]                  
Maximum annual contributions per employee, percent         4.00% 4.00%      
Defined contribution plan, cost         $ 705,000 $ 569,000      
Fair Value, Recurring | Warrants Liability | Measurement Input, Risk Free Interest Rate                  
Summary of Significant Accounting Policies [Line Items]                  
Warrant measurement input     0.0007   0.001 0.012      
Fair Value, Recurring | Warrants Liability | Measurement Input, Price Volatility                  
Summary of Significant Accounting Policies [Line Items]                  
Warrant measurement input     0.70   0.75 0.70      
Geographic Distribution, Foreign                  
Summary of Significant Accounting Policies [Line Items]                  
Weighted average interest rate         0.01% 0.03%      
Paycheck Protection Program                  
Summary of Significant Accounting Policies [Line Items]                  
Unsecured debt               $ 3,516,000  
Notes payable         $ 3,012,000        
Series A preferred stocks | Fair Value, Recurring | Warrants Liability                  
Summary of Significant Accounting Policies [Line Items]                  
Expiration term of warrant (in years)     9 months 18 days   1 year 7 months 6 days        
Series C preferred stocks | Fair Value, Recurring | Warrants Liability                  
Summary of Significant Accounting Policies [Line Items]                  
Expiration term of warrant (in years)     7 months 6 days   1 year 6 months 2 years 6 months      
SSIG | Grant Agreement                  
Summary of Significant Accounting Policies [Line Items]                  
Related party transaction $ 504,000       $ 504,000        
Affiliated Entity | SSIG                  
Summary of Significant Accounting Policies [Line Items]                  
Proceeds from grant $ 504,000                
ION Acquisition Corp 2 LTD                  
Summary of Significant Accounting Policies [Line Items]                  
Deferred offering costs     $ 8,855,000   140,778   $ 14,438,150    
Offering costs         165,778   $ 14,438,150    
Unrecognized tax benefits     0   $ 0        
Unrecognized tax benefits, interest   $ 0 0            
Unrecognized tax benefits, penalties   0 0            
Taxes on income   $ 0 $ 0            
Expiration term of warrant (in years)     5 years   5 years        
ION Acquisition Corp 2 LTD | Class B ordinary shares                  
Summary of Significant Accounting Policies [Line Items]                  
Shares subject to forfeiture (in shares) | shares         825,000