Product Sales - Schedule of Net Product Sales (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 1,952.0	$ 1,577.8	$ 3,780.2	$ 2,950.4
Product
Disaggregation of Revenue [Line Items]
Revenues	1,226.9	1,205.3	2,463.6	2,309.7
UNITED STATES | EYLEA
Disaggregation of Revenue [Line Items]
Revenues	1,113.7	1,160.3	2,285.7	2,234.4
UNITED STATES | Libtayo
Disaggregation of Revenue [Line Items]
Revenues	63.3	40.8	125.0	67.6
UNITED STATES | Praluent
Disaggregation of Revenue [Line Items]
Revenues	47.2		47.2
UNITED STATES | ARCALYST
Disaggregation of Revenue [Line Items]
Revenues	2.7	4.2	5.7	7.7
UNITED STATES | Product
Disaggregation of Revenue [Line Items]
Revenues	$ 1,226.9	$ 1,205.3	$ 2,463.6	$ 2,309.7