Legal Matters (Details) $ in Millions	Jul. 31, 2017 claim	Sep. 26, 2016 EUR (€)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Feb. 25, 2019 claim	Feb. 14, 2019 claim
Loss Contingencies [Line Items]
Loss contingency accrual | $			$ 117.0	$ 100.0
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