Legal Matters (Details) € in Thousands	Jul. 31, 2017 claim	Sep. 26, 2016 EUR (€)	Apr. 01, 2019 claim	Feb. 25, 2019 claim	Feb. 14, 2019 claim
Amgen v.s. Regeneron | Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, damages sought, per unit produced | €		€ 10
Loss contingency, damages sought | €		€ 10,000
'165 Patent | Amgen v.s. Regeneron | Pending Litigation
Loss Contingencies [Line Items]
Pending claims				2
Invalid claims				2
'487 Patent
Loss Contingencies [Line Items]
Number of IPR filed	2
Number of claims invalidated					17
'741 Patent | Amgen v.s. Regeneron | Pending Litigation
Loss Contingencies [Line Items]
Pending claims				1
'688 Patent | Pending Litigation
Loss Contingencies [Line Items]
Asserted claims			9