Quarterly report pursuant to Section 13 or 15(d)

Presentation and Summary of Significant Accounting Policies - Additional Information (Details)

v3.20.2
Presentation and Summary of Significant Accounting Policies - Additional Information (Details)
$ in Thousands
3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2020
USD ($)
Customer
Jun. 30, 2019
USD ($)
Customer
Jun. 30, 2020
USD ($)
Customer
Jun. 30, 2019
USD ($)
Customer
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Apr. 15, 2020
USD ($)
Significant Accounting Policies [Line Items]              
Positive (negative) cash flows from operations     $ (2,777) $ (16,606) $ (30,117) $ (41,770)  
Net loss $ 11,793 $ 16,691 24,477 32,997 62,078 $ 61,104  
Accumulated deficit 256,966   256,966   232,489    
Proceeds from common stock offerings, net     6,527 $ 11,778      
Proceeds from the exercise of warrants     2,100        
Cash and cash equivalents 50,081   50,081   $ 44,065    
Transaction price remaining performance obligations $ 4,463   $ 4,463        
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]              
Significant Accounting Policies [Line Items]              
Number of major customers | Customer 10 10 10 10      
Concentration risk percentage 40.00% 26.00% 34.00% 25.00%      
Customer One [Member] | Sales Revenue, Net [Member] | Customer Concentration Risk [Member]              
Significant Accounting Policies [Line Items]              
Number of major customers | Customer 1            
Concentration risk percentage 11.00%            
Other Customer [Member] | Sales Revenue, Net [Member] | Customer Concentration Risk [Member]              
Significant Accounting Policies [Line Items]              
Number of major customers | Customer   0 0 0      
Concentration risk percentage   10.00% 10.00% 10.00%      
Paycheck Protection Program [Member]              
Significant Accounting Policies [Line Items]              
Unsecured loans aggregate amount             $ 6,491
Equity Distribution Agreement [Member]              
Significant Accounting Policies [Line Items]              
Proceeds from common stock offerings, net     $ 6,006        
Equity Distribution Agreement [Member] | Maximum [Member]              
Significant Accounting Policies [Line Items]              
Aggregate available offering price, common stock     $ 18,538