Intangible Assets and Goodwill (Schedule of Intangible Assets and Goodwill) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$ 298.0
Intangible Assets, Cost	4,778.4	$ 4,760.4
Intangible Assets, Accumulated Amortization	1,434.1	1,119.1
Intangible assets, net	3,344.3	3,641.3
Goodwill, Cost	5,040.3	5,040.3
Goodwill, Accumulated Amortization	2.9	2.9
Goodwill	5,037.4	5,037.4
Licensing Agreements
Intangible Assets [Line Items]
Finite-lived Intangible Assets, Cost	57.0	39.0
Finite-lived Intangible Assets, Accumulated Amortization	(34.7)	(29.3)
Finite-lived Intangible Assets, Net	22.3	9.7
Patents [Member]
Intangible Assets [Line Items]
Finite-lived Intangible Assets, Cost	10.5	10.5
Finite-lived Intangible Assets, Accumulated Amortization	(10.5)	(10.5)
Finite-lived Intangible Assets, Net	$ 0.0	0.0
Intangible Assets, Estimated Life (months)	7 years
Purchased Technology [Member]
Intangible Assets [Line Items]
Finite-lived Intangible Assets, Cost	$ 4,710.5	4,710.5
Finite-lived Intangible Assets, Accumulated Amortization	(1,388.7)	(1,079.1)
Finite-lived Intangible Assets, Net	3,321.8	3,631.4
Other Intangibles [Member]
Intangible Assets [Line Items]
Finite-lived Intangible Assets, Cost	0.4	0.4
Finite-lived Intangible Assets, Accumulated Amortization	(0.2)	(0.2)
Finite-lived Intangible Assets, Net	$ 0.2	$ 0.2
Intangible Assets, Estimated Life (months)	5 years
Minimum | Licensing Agreements
Intangible Assets [Line Items]
Intangible Assets, Estimated Life (months)	3 years
Minimum | Purchased Technology [Member]
Intangible Assets [Line Items]
Intangible Assets, Estimated Life (months)	6 years
Maximum | Licensing Agreements
Intangible Assets [Line Items]
Intangible Assets, Estimated Life (months)	8 years
Maximum | Purchased Technology [Member]
Intangible Assets [Line Items]
Intangible Assets, Estimated Life (months)	16 years
Synageva BioPharma Corp. [Member] | Purchased Technology [Member]
Intangible Assets [Line Items]
Finite-lived Intangible Assets, Net	$ 2,992.4