Annual report pursuant to Section 13 and 15(d)

Commitments and Contingencies - Narrative (Details)

v3.19.1
Commitments and Contingencies - Narrative (Details)
$ in Millions
 3 Months Ended 12 Months Ended
Dec. 31, 2018
USD ($)
ft²
Dec. 31, 2018
USD ($)
ft²
extension_option
lease_agreement
Dec. 31, 2017
USD ($)
Loss Contingencies [Line Items]      
Rent expense (per month) | $   $ 0.5 $ 0.5
Freising, Germany      
Loss Contingencies [Line Items]      
Number of lease agreements | lease_agreement   4  
Area of leased property   19,000  
Boston, Massachusetts      
Loss Contingencies [Line Items]      
Area of leased property   3,950  
Hallbergmoos, Germany      
Loss Contingencies [Line Items]      
Area of leased property 105,000    
Lease term   150 months  
Number of agreement extension options | extension_option   2  
Lease extension term   60 months  
Rent expense (per month) | $   $ 0.2  
Security deposit | $ $ 0.8 $ 0.8  
Leases in Same Building | Freising, Germany      
Loss Contingencies [Line Items]      
Number of lease agreements | lease_agreement   3  
Leases with Defined Termination Date | Freising, Germany      
Loss Contingencies [Line Items]      
Number of lease agreements | lease_agreement   2  
Leases Expected to be Delivered by December 2019 | Hallbergmoos, Germany      
Loss Contingencies [Line Items]      
Area of leased property 96,400    
Leases Expected to be Delivered by May 2020 | Hallbergmoos, Germany      
Loss Contingencies [Line Items]      
Area of leased property 8,600    
Leases Expected to be Delivered by October 2024 | Hallbergmoos, Germany      
Loss Contingencies [Line Items]      
Area of leased property 22,300    
Leases with First Right of Refusal for Additional Area | Hallbergmoos, Germany      
Loss Contingencies [Line Items]      
Area of leased property 13,400