Legal Matters (Details) $ in Millions	Jul. 31, 2017 claim	Sep. 26, 2016 EUR (€)	Dec. 31, 2019 USD ($)	Apr. 01, 2019 claim	Feb. 25, 2019 claim	Feb. 14, 2019 claim	Dec. 31, 2018 USD ($)
Loss Contingencies [Line Items]
Accruals for loss contingencies | $			$ 100.0				$ 30.0
Amgen v.s. Regeneron | Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, damages sought, per unit produced | €		€ 10,000
Loss contingency, damages sought | €		€ 10,000,000.0
'165 Patent | Amgen v.s. Regeneron | Pending Litigation
Loss Contingencies [Line Items]
Pending claims					2
Invalid claims					2
'741 Patent | Amgen v.s. Regeneron | Pending Litigation
Loss Contingencies [Line Items]
Pending claims					1
'487 Patent
Loss Contingencies [Line Items]
Number of IPR filed	2
Number of claims invalidated						17
'688 Patent | Pending Litigation
Loss Contingencies [Line Items]
Asserted claims				9