Accrued expenses and other current liabilities (Details) $ in Thousands, € in Millions		6 Months Ended
	Nov. 30, 2016 USD ($)	Jun. 30, 2017 EUR (€)	Jun. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Accrued expenses and other current liabilities
Accruals for services provided by vendors-not yet billed				$ 3,092	$ 3,824
Personnel related accruals and liabilities				3,974	5,559
Other current liabilities				2,374	383
Total				9,440	$ 9,766
Severance costs	$ 1,100		$ 900
Restructuring Reserve
Beginning Balance			1,148
Accrued through profit and loss			908
Payments			(1,435)
Currency translation effects			48
Ending Balance			669
Glybera
Restructuring Reserve
Repayment of upfront payment		€ 2.0	$ 2,300
Accrued liability towards repayment of installments		1.5		1,700
Additional payment depending on the number of patients treated before withdrawal		1.8		2,000
Glybera | Other Current Liabilities
Restructuring Reserve
Accrued liability current towards repayment of installments		€ 0.5		600
Accrued liability current in relation to Phase IV termination				600
Glybera | Other Expense
Restructuring Reserve
Accrued liability in relation to Phase IV termination				$ 900