Product Sales - Schedule of Net Product Sales (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Revenues	$ 3,720.7	$ 3,362.7	$ 10,412.8	$ 9,682.9
Net product sales
Disaggregation of Revenue [Line Items]
Revenues	1,946.4	1,786.1	5,626.3	5,226.2
Libtayo
Disaggregation of Revenue [Line Items]
Revenues	288.6	232.4	849.9	619.3
Inmazeb
Disaggregation of Revenue [Line Items]
Revenues	35.6	3.3	36.6	7.7
U.S. \| ELYEA HD And EYLEA
Disaggregation of Revenue [Line Items]
Revenues	1,536.9	1,490.9	4,473.2	4,424.8
U.S. \| ELYEA HD
Disaggregation of Revenue [Line Items]
Revenues	392.3	42.7	896.5	42.7
U.S. \| EYLEA
Disaggregation of Revenue [Line Items]
Revenues	1,144.6	1,448.2	3,576.7	4,382.1
U.S. \| Libtayo
Disaggregation of Revenue [Line Items]
Revenues	194.5	144.1	536.1	384.0
U.S. \| Praluent
Disaggregation of Revenue [Line Items]
Revenues	52.9	40.4	179.0	121.1
U.S. \| Evkeeza
Disaggregation of Revenue [Line Items]
Revenues	32.4	19.1	87.6	53.3
Rest Of World \| Libtayo
Disaggregation of Revenue [Line Items]
Revenues	$ 94.1	$ 88.3	$ 313.8	$ 235.3