Quarterly report pursuant to Section 13 or 15(d)

FAIR VALUE MEASUREMENTS - Recurring (Details)

v3.21.2
FAIR VALUE MEASUREMENTS - Recurring (Details)
$ / shares in Units, $ in Thousands
9 Months Ended 12 Months Ended
Sep. 30, 2021
USD ($)
$ / shares
Dec. 31, 2020
USD ($)
Money Market Funds    
Assets    
Net Asset Value Per Share | $ / shares $ 1.00  
Warrant    
Assets    
Equity Securities, FV-NI, Measurement Input 0.94 1.37
Equity Securities, FV-NI, Measurement Input [Extensible List] Volatility Volatility
Input increase (decrease) assumption, as a percent 20.00% 20.00%
Estimated change in fair value due to change in input $ 22 $ 115
Fair Value, Recurring [Member] | Short-term Investments [Member]    
Assets    
Assets at fair value 53,532 21,313
Fair Value, Recurring [Member] | Money Market Funds    
Assets    
Assets at fair value 18,481 8,636
Fair Value, Recurring [Member] | Corporate Bonds    
Assets    
Assets at fair value 35,051 12,677
Fair Value, Recurring [Member] | Warrant    
Assets    
Assets at fair value 18 239
Fair Value, Recurring [Member] | Common Stock [Member]    
Assets    
Assets at fair value 7,282  
Fair Value, Recurring [Member] | Preferred stock    
Assets    
Assets at fair value   5,173
Fair Value, Recurring [Member] | Notes Receivable [Member]    
Assets    
Assets at fair value   5,876
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 | Short-term Investments [Member]    
Assets    
Assets at fair value 18,481 8,636
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 | Money Market Funds    
Assets    
Assets at fair value 18,481 8,636
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 | Corporate Bonds    
Assets    
Assets at fair value 0 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 | Warrant    
Assets    
Assets at fair value 0 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 | Common Stock [Member]    
Assets    
Assets at fair value 7,282  
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 | Preferred stock    
Assets    
Assets at fair value   0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 | Notes Receivable [Member]    
Assets    
Assets at fair value   0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 | Short-term Investments [Member]    
Assets    
Assets at fair value 35,051 12,677
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 | Money Market Funds    
Assets    
Assets at fair value 0 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 | Corporate Bonds    
Assets    
Assets at fair value 35,051 12,677
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 | Warrant    
Assets    
Assets at fair value 0 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 | Common Stock [Member]    
Assets    
Assets at fair value 0  
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 | Preferred stock    
Assets    
Assets at fair value   0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 | Notes Receivable [Member]    
Assets    
Assets at fair value   0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 | Short-term Investments [Member]    
Assets    
Assets at fair value 0 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 | Money Market Funds    
Assets    
Assets at fair value 0 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 | Corporate Bonds    
Assets    
Assets at fair value 0 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 | Warrant    
Assets    
Assets at fair value 18 239
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 | Common Stock [Member]    
Assets    
Assets at fair value $ 0  
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 | Preferred stock    
Assets    
Assets at fair value   5,173
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 | Notes Receivable [Member]    
Assets    
Assets at fair value   $ 5,876