Summary of significant accounting policies (Details) - USD ($)
$ in Thousands
Dec. 31, 2019
Oct. 22, 2019
Aug. 01, 2019
Jun. 30, 2019
Apr. 01, 2019
Mar. 31, 2019
Recently adopted accounting pronouncements            
Right-to-use liability $ 4,897     $ 4,363    
Property, plant and equipment, net 5,654         $ 12,159
Right-to-use asset 4,731 $ 18,425 $ 2,368      
Lease liabilities, current 1,011          
Lease liabilities, non-current 3,886          
Accrued expenses 4,557         2,801
Deferred rent, net of current portion           24
Financing obligation           6,561
Accumulated deficit $ (96,509)         $ (59,766)
ASU 2016-02            
Recently adopted accounting pronouncements            
Right-to-use liability         $ 837  
Property, plant and equipment, net         645  
Right-to-use asset         789  
Long term prepaid rent         5,006  
Lease liabilities, current         388  
Lease liabilities, non-current         449  
Accrued expenses         2,777  
Accumulated deficit         (59,673)  
ASU 2016-02 | Adjustments            
Recently adopted accounting pronouncements            
Property, plant and equipment, net         (11,514)  
Right-to-use asset         789  
Long term prepaid rent         5,006  
Lease liabilities, current         388  
Lease liabilities, non-current         449  
Accrued expenses         (24)  
Deferred rent, net of current portion         (24)  
Financing obligation         (6,561)  
Accumulated deficit         $ 93