Income Taxes (Deferred Tax Assets (Liabilities) Resulting From Temporary Differences) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Tax loss and deduction carryforwards	$ 2,111.5	$ 2,144.3
Tax credit carryforwards	658.3	830.5
All other future deductions	485.5	560.8
Valuation allowance	(2,960.0)	(3,257.5)
Total deferred tax assets	295.3	278.1
Deferred tax liabilities:
Total deferred tax liabilities	(142.2)	(85.1)
Net deferred tax assets	$ 153.1	$ 193.0