Collaboration, License, and Other Agreements - Schedule of Collaboration Revenue Earned From Bayer (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 12,172.9	$ 16,071.7	$ 8,497.1
Outside United States | Bayer | Other collaboration revenue | Regeneron's share of profits in connection with commercialization of EYLEA outside the United States
Disaggregation of Revenue [Line Items]
Revenues	1,317.4	1,349.2	1,107.9
Outside United States | Bayer | Other collaboration revenue | Reimbursement for manufacturing of commercial supplies
Disaggregation of Revenue [Line Items]
Revenues	91.4	60.1	78.2
Outside United States | Bayer | Other collaboration revenue | One-time payment in connection with change in Japan arrangement
Disaggregation of Revenue [Line Items]
Revenues	21.9	0.0	0.0
Outside United States | Bayer | Reduction of R&D expense | Reimbursement of R&D expenses
Disaggregation of Revenue [Line Items]
Revenues	51.0	46.1	46.7
Outside United States | Bayer | Reduction of R&D expense | Regeneron's obligation for its share of Bayer R&D expenses
Disaggregation of Revenue [Line Items]
Revenues	$ (34.3)	$ (40.9)	$ (35.8)