Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Condensed Financial Statements (Details)

v3.20.1
Summary of Significant Accounting Policies - Condensed Financial Statements (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Jan. 01, 2019
Dec. 31, 2017
Statement of Financial Position [Abstract]        
Prepaid expenses and other current assets $ 4,072 $ 4,574 $ 5,290  
Other non-current assets 3,146 910 2,030  
Assets 141,097 141,341 143,177  
Deferred revenues, current portion 11,256 35,612    
Deferred revenue, net of current portion 47,258 53,303 56,780  
Total Liabilities 89,745 101,406 104,883  
Accumulated Deficit (174,176) (147,066) (148,707)  
Total stockholders' equity 51,352 39,935 38,294 $ 11,522
Total liabilities and stockholders' equity 141,097 141,341 143,177  
Income Statement [Abstract]        
Revenue 46,279 29,101    
General and administrative 18,440 18,442    
Loss from operations (27,157) (30,831)    
Loss before income taxes (25,469) (27,066)    
Net loss (25,469) (26,754)    
Comprehensive loss (24,482) $ (25,041)    
Calculated under Revenue Guidance in Effect before Topic 606        
Statement of Financial Position [Abstract]        
Prepaid expenses and other current assets 3,948      
Other non-current assets 2,331      
Assets 140,158      
Deferred revenues, current portion 14,638      
Deferred revenue, net of current portion 38,189      
Total Liabilities 84,058      
Accumulated Deficit (169,428)      
Total stockholders' equity 56,100      
Total liabilities and stockholders' equity 140,158      
Income Statement [Abstract]        
Revenue 48,594      
General and administrative 17,582      
Loss from operations (25,700)      
Loss before income taxes (24,012)      
Net loss (24,012)      
Comprehensive loss (23,025)      
Accounting Standards Update 2014-09        
Statement of Financial Position [Abstract]        
Prepaid expenses and other current assets     716  
Other non-current assets     1,120  
Assets     1,836  
Deferred revenue, net of current portion     3,477  
Total Liabilities     3,477  
Accumulated Deficit     (1,641)  
Total stockholders' equity     (1,641)  
Total liabilities and stockholders' equity     $ 1,836  
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606        
Statement of Financial Position [Abstract]        
Prepaid expenses and other current assets (124)      
Other non-current assets (815)      
Assets (939)      
Deferred revenues, current portion 3,382      
Deferred revenue, net of current portion (9,069)      
Total Liabilities (5,687)      
Accumulated Deficit 4,748      
Total stockholders' equity 4,748      
Total liabilities and stockholders' equity (939)      
Income Statement [Abstract]        
Revenue 2,315      
General and administrative (858)      
Loss from operations 1,457      
Loss before income taxes 1,457      
Net loss 1,457      
Comprehensive loss $ 1,457