Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.1
Presentation and Summary of Significant Accounting Policies - Additional Information (Details)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2020
USD ($)
Customer
Mar. 31, 2019
USD ($)
Customer
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Apr. 15, 2020
USD ($)
Significant Accounting Policies [Line Items]          
Positive (negative) cash flows from operations $ 1,503 $ (4,632) $ (30,117) $ (41,770)  
Net loss 12,684 16,306 62,078 $ 61,104  
Accumulated deficit 245,173   232,489    
Proceeds from common stock offerings, net 3,505 $ 4,160      
Cash and cash equivalents 49,165   $ 44,065    
Transaction price remaining performance obligations $ 5,767        
Transaction price remaining performance obligations percentage 64.00%        
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]          
Significant Accounting Policies [Line Items]          
Number of major customers | Customer 10 10      
Concentration risk percentage 32.00% 28.00%      
Paycheck Protection Program [Member] | Subsequent Event [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 $ 2,984        
Equity Distribution Agreement [Member] | Maximum [Member]          
Significant Accounting Policies [Line Items]          
Aggregate available offering price, common stock $ 21,737