Debt - Narrative (Details) - Line of Credit - USD ($)
1 Months Ended 3 Months Ended 6 Months Ended 9 Months Ended
Aug. 12, 2019
Jun. 17, 2019
Dec. 15, 2017
Oct. 31, 2017
Aug. 31, 2019
Jun. 30, 2019
Dec. 31, 2017
Jun. 16, 2019
Sep. 30, 2020
Sep. 30, 2019
Dec. 31, 2019
Sep. 30, 2017
Aug. 31, 2017
Aug. 24, 2017
Madryn Credit Agreement                            
Debt Instrument [Line Items]                            
Maximum borrowing capacity   $ 25,000,000.0                       $ 65,000,000.0
Borrowings on credit facility         $ 25,000,000.0   $ 10,000,000.0              
Outstanding principal balance             40,000,000.0   $ 65,000,000   $ 65,000,000      
Default interest rate                 4.00%          
Effective interest rate                 18.40%          
Weighted average interest rate                 10.60%          
Interest expense                 $ 5,900,000 $ 4,500,000        
Fair value of options                         $ 15,100,000  
Debt discount         1,600,000   $ 5,000,000.0              
Legal expenses         $ 300,000             $ 1,300,000    
Madryn Credit Agreement | London Interbank Offered Rate (LIBOR)                            
Debt Instrument [Line Items]                            
Credit agreement interest rate   8.00%           11.00%            
Amended Madryn Credit Agreement                            
Debt Instrument [Line Items]                            
Interest expense           $ 300,000     $ 700,000          
Madryn Credit Agreement - Term A                            
Debt Instrument [Line Items]                            
Maximum borrowing capacity                           $ 30,000,000.0
Madryn Credit Agreement - Term B-1                            
Debt Instrument [Line Items]                            
Borrowings on credit facility       $ 5,000,000.0                    
Madryn Credit Agreement - Term B-2                            
Debt Instrument [Line Items]                            
Borrowings on credit facility     $ 5,000,000.0                      
Madryn Credit Agreement - Term B-3 And B-4                            
Debt Instrument [Line Items]                            
Borrowings on credit facility $ 25,000,000.0                          
Madryn Credit Agreement - Term B-3                            
Debt Instrument [Line Items]                            
Additional borrowing capacity   $ 10,000,000.0                        
Madryn Credit Agreement - Term B-4                            
Debt Instrument [Line Items]                            
Additional borrowing capacity   $ 15,000,000.0