Summary of Significant Accounting Policies - Property, plant and equipment (Details)	12 Months Ended
	Dec. 31, 2017
IT equipment | Minimum
Property, Plant and Equipment
Estimated useful life of property, plant and equipment	3 years
IT equipment | Maximum
Property, Plant and Equipment
Estimated useful life of property, plant and equipment	5 years
Laboratory equipment | Minimum
Property, Plant and Equipment
Estimated useful life of property, plant and equipment	5 years
Laboratory equipment | Maximum
Property, Plant and Equipment
Estimated useful life of property, plant and equipment	10 years
Other equipment | Minimum
Property, Plant and Equipment
Estimated useful life of property, plant and equipment	3 years
Other equipment | Maximum
Property, Plant and Equipment
Estimated useful life of property, plant and equipment	10 years