Summary of significant accounting policies (Details)	3 Months Ended
	Mar. 31, 2020 issuer item instrument
Concentrations of Credit Risk
Number of issuer to which company limits the amount of credit exposure other than US Government guaranteed securities | issuer	1
Number of financial investment to which company limits the amount of credit exposure other than US Government guaranteed securities | instrument	1
Variable Interest Entities
Number of entities in which variable interest held | item	0
JAKAFI
Inventory
Shelf life for finished goods inventory, maximum	36 months
ICLUSIG
Inventory
Shelf life for finished goods inventory, maximum	36 months