Income Taxes (Schedule of Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating losses	$ 102.9	$ 41.8
Income tax credits	328.1	371.6
Stock compensation	57.1	47.6
Accruals and allowances	65.2	105.8
Unrealized losses	18.8	0.0
Research and development expenses	3.5	5.2
Accrued royalties	0.8	89.1
ROU leases	46.2	0.0
Intangible assets	1,967.3	0.0
Gross deferred tax assets	2,589.9	661.1
Valuation allowance	(72.6)	(19.6)
Total deferred tax assets	2,517.3	641.5
Deferred tax liabilities:
Depreciable assets	(5.1)	(88.7)
Unrealized gains	0.0	(6.6)
Investment in foreign partnership	(2,249.5)	(566.6)
ROU leases	(53.9)	0.0
Intangible liabilities	0.0	(268.8)
Total deferred tax liabilities	(2,308.5)	(930.7)
Net deferred tax (liability) asset	$ 208.8
Net deferred tax (liability) asset		$ (289.2)