Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Tax Credit Carryforward [Line Items]
One-time tax reserves	$ 256.9	$ 98.7
Net increase (decrease) in valuation allowance	(297.5)
Net benefit related to U.S. Tax Reform			$ 29.9
Valuation allowance release related to U.S Tax Reform			33.5
Uncertain tax position related to U.S Tax Reform			3.6
Write-off of deferred tax asset related to U.S. Tax Reform			161.4
Reversal of deferred tax liability related to unremitted earnings due to U.S. Tax Reform			66.7
Establishment of deferred tax assets for other miscellaneous withholding tax items due to U.S. Tax Reform			5.5
One-time tax on offshore earnings due to U.S. Tax Reform			2.9
Deferred tax assets, tax credit carryforwards, excluding adoption of ASU 2013-11	670.3
Tax credit carryforward, valuation allowance	649.5
Tax credit carryforwards subject to offset of ASU 2013-11	11.9
Foreign tax credit carryforwards	629.5
Tax credit carryforwards, research	21.6
Deferred tax assets, not subject to expiration	8.9
Tax credit carryforward	10.3
Deferred tax assets, net operating loss	2,136.5
Operating loss carryforwards, valuation allowance	2,018.6
Operating loss carryforwards subject to offset in accordance with ASU 2013--11	25.0
Operating loss carryforwards	1,443.7
Change in deferred tax liability associated with undistributed earnings	12.5
Deferred tax liabilities, undistributed foreign earnings	6.1
Undistributed earnings of foreign subsidiaries	1,200.0
Total gross unrecognized tax benefits	331.7	137.6	48.6	$ 58.7
Unrecognized tax benefits that would impact effective tax rate	130.9
Expense for interest and penalties	1.0
Accrued interest and penalties	6.3	7.4
Foreign
Tax Credit Carryforward [Line Items]
Deferred tax assets, net operating loss	2,011.5
Operating loss carryforwards, valuation allowance	1,918.5
State and Local Jurisdiction
Tax Credit Carryforward [Line Items]
Operating loss carryforwards, valuation allowance	100.0
Deferred tax assets, state tax loss carryforwards	100.0
Europe, Middle East & Africa
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance			$ 25.5
Foreign
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	9,553.3
Deferred tax asset, not subject to expiration	7,611.6
Undistributed earnings of foreign subsidiaries	1,941.5
Deferred Tax Assets Utilization Of Foreign Tax Credits
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance	(232.5)
Deferred Tax Assets Tax Rate Change And Write Off
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance	$ (66.5)
Deferred Tax Asset Generated In Current Year
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance		138.6
Deferred Tax Assets Expensed Or Written Off In Current Year
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance		93.0
Excess Tax Basis Reallocated
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance		57.2
State Deferred Tax Assets
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance		15.3
Other Deferred Tax Assets
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance		11.7
Deferred Tax Assets Associated With Repatriation Of Earnings
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance		$ 8.8