Concentration of credit risk and current expected credit losses (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Net Product Revenues | Customer Concentration Risk | Customer A
Concentration of risk
Percentage of concentration risk	19.00%	18.00%
Net Product Revenues | Customer Concentration Risk | Customer B
Concentration of risk
Percentage of concentration risk	13.00%	15.00%
Net Product Revenues | Customer Concentration Risk | Customer C
Concentration of risk
Percentage of concentration risk	18.00%	16.00%
Net Product Revenues | Customer Concentration Risk | Customer D
Concentration of risk
Percentage of concentration risk	11.00%	12.00%
Accounts Receivable | Credit Concentration Risk | Collaboration Partner A, B, C and D
Concentration of risk
Percentage of concentration risk	24.00%		30.00%
Accounts Receivable | Credit Concentration Risk | Customer A, B, C and D
Concentration of risk
Percentage of concentration risk	40.00%		39.00%