Quarterly report pursuant to Section 13 or 15(d)

RECEIVABLES - Narrative (Details)

v3.21.2
RECEIVABLES - Narrative (Details) - USD ($)
 9 Months Ended 12 Months Ended
Sep. 30, 2021
Dec. 31, 2020
Receivables [Abstract]    
Allowance for doubtful accounts $ 0 $ 0
Notes Receivable    
Concentration Risk [Line Items]    
Maximum amount of loss $ 3,800,000  
Customer concentration | Total receivables | Apple, Inc.    
Concentration Risk [Line Items]    
Concentration percentage 47.90% 48.90%
Customer concentration | Total receivables | Google, Inc.    
Concentration Risk [Line Items]    
Concentration percentage 38.30% 42.70%
Customer concentration | Total notes receivable | Notes Receivable    
Concentration Risk [Line Items]    
Concentration percentage 77.30%  
Customer concentration | Total notes receivable | Notes Receivable | Certain intellectual property created, developed or acquired by the developers    
Concentration Risk [Line Items]    
Concentration percentage 67.20%