Intangible assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Intangible assets
Total intangible assets	$ 14,388		$ 14,388		$ 12,707
Less accumulated amortization	(5,642)		(5,642)		(4,383)
Intangible assets, net	8,746		8,746		8,324
Amortization expense	700	$ 200	800	$ 300
Licenses
Intangible assets
Total intangible assets	9,058		9,058		7,799
Acquired research & development
Intangible assets
Total intangible assets	5,330		5,330		$ 4,908
Chiesi Pharmaceutical | Other Expense
Intangible assets
Amortization expense	$ 600		$ 600