Segment Information - Geographic Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Revenue, Major Customer [Line Items]
Revenue	$ 9,890.6	$ 9,675.9	$ 9,835.6
Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	9,890.6	9,675.9	9,835.6
Long-lived assets	3,320.8	3,537.7	3,729.7
U.S. | Reportable Segment
Revenue, Major Customer [Line Items]
Long-lived assets	1,236.7	1,366.1	1,443.0
Europe | Reportable Segment
Revenue, Major Customer [Line Items]
Long-lived assets	2,053.8	2,139.2	2,248.0
Germany | Reportable Segment
Revenue, Major Customer [Line Items]
Long-lived assets	12.2	13.3	17.5
Asia | Reportable Segment
Revenue, Major Customer [Line Items]
Long-lived assets	5.9	8.5	8.3
Other | Reportable Segment
Revenue, Major Customer [Line Items]
Long-lived assets	12.2	10.6	12.9
Product revenue, net
Revenue, Major Customer [Line Items]
Revenue	7,119.4	7,213.5	7,246.7
Product revenue, net | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	7,119.4	7,213.5	7,246.7
Product revenue, net | U.S.
Revenue, Major Customer [Line Items]
Revenue	3,547.9	3,237.3	3,141.4
Product revenue, net | U.S. | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	3,547.9	3,237.3	3,141.4
Product revenue, net | Europe | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	1,871.6	2,171.5	2,127.4
Product revenue, net | Germany | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	853.0	955.6	868.0
Product revenue, net | Asia | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	419.1	366.9	649.4
Product revenue, net | Other | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	427.8	482.2	460.5
Revenue from anti-CD20 therapeutic programs
Revenue, Major Customer [Line Items]
Revenue	1,860.6	1,749.9	1,689.6
Revenue from anti-CD20 therapeutic programs | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	1,860.6	1,749.9	1,689.6
Revenue from anti-CD20 therapeutic programs | U.S. | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	1,775.4	1,673.6	1,618.5
Revenue from anti-CD20 therapeutic programs | Europe | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	1.8	0.6	0.4
Revenue from anti-CD20 therapeutic programs | Germany | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	0.0	0.0	0.0
Revenue from anti-CD20 therapeutic programs | Asia | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	0.0	0.0	0.0
Revenue from anti-CD20 therapeutic programs | Other | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	83.4	75.7	70.7
Contract manufacturing, royalty and other revenue
Revenue, Major Customer [Line Items]
Revenue	732.9	652.6	899.3
Contract manufacturing, royalty and other revenue | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	732.9	652.6	899.3
Contract manufacturing, royalty and other revenue | U.S. | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	414.7	395.0	673.6
Contract manufacturing, royalty and other revenue | Europe | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	10.8	0.4	11.7
Contract manufacturing, royalty and other revenue | Germany | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	0.0	0.0	0.0
Contract manufacturing, royalty and other revenue | Asia | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	307.4	257.2	214.0
Contract manufacturing, royalty and other revenue | Other | Reportable Segment
Revenue, Major Customer [Line Items]
Revenue	$ 0.0	$ 0.0	$ 0.0