Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Tax Credit Carryforward [Line Items]
Change in estimate related to restructuring transactions		$ 30.5
One-time tax reserves			$ 256.9
Deferred tax assets with full valuation allowance	$ 1,638.0	635.0
Deferred tax asset, potential valuation allowance	67.0
Valuation allowance recorded against deferred tax assets	8.0
Deferred tax asset, valuation allowance, excluding de-valued deferred tax assets	126.0	2.6
Deferred tax assets, tax credit carryforwards, excluding adoption of ASU 2013-11	119.7
Tax credit carryforward, valuation allowance	119.7
Foreign tax credit carryforwards	87.6
Tax credit carryforwards, research	23.7
Tax credit carryforward	8.4
Deferred tax assets, net operating loss	393.7
Operating loss carryforwards, valuation allowance	322.4
Operating loss carryforwards subject to offset in accordance with ASU 2013--11	22.4
Tax loss and deduction carryforwards	425.0	1,997.5
Valuation allowance	815.4	2,327.6
Undistributed earnings of foreign subsidiaries	1,200.0
Decrease in deferred tax liability associated with undistributed earnings of foreign subsidiaries	7.9
Total gross unrecognized tax benefits	251.7	372.1	331.7	$ 137.6
Unrecognized tax benefits that would impact effective tax rate	95.8
Expense (reversal of expense) for interest and penalties	0.5	1.0	(1.0)
Accrued interest and penalties	7.1	6.8
Minimum
Tax Credit Carryforward [Line Items]
Increase in unrecognized tax benefits is reasonably possible	5.0
Maximum
Tax Credit Carryforward [Line Items]
Increase in unrecognized tax benefits is reasonably possible	10.0
United Kingdom Tax Authority
Tax Credit Carryforward [Line Items]
Foreign income tax benefit	89.0	21.0
Foreign
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	2,599.0
Deferred tax asset, not subject to expiration	1,059.2
Deferred tax assets, operating loss carryforwards, subject to expiration	1,539.8
Domestic
Tax Credit Carryforward [Line Items]
Tax loss and deduction carryforwards	31.4
Deferred tax asset, not subject to expiration	149.3
Deferred Tax Assets That Cannot Be Benefitted
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance	164.0	65.1
Deferred Tax Assets Generated In Current Year
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance	71.0	69.9
Deferred Tax Asset, Tax On Foreign Income
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance	89.0	21.0
Deferred Tax Assets, Change In Judgment
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance	4.0	4.7
Deferred Tax Assets, True-up Adjustment
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance		(30.5)
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 Associated With Merger
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance		(81.8)
Deferred tax assets with full valuation allowance		465.0
Deferred Tax Asset Realization Remote
Tax Credit Carryforward [Line Items]
Deferred tax assets with full valuation allowance		170.0
Deferred Tax Asset Realization Remote | Foreign
Tax Credit Carryforward [Line Items]
Deferred tax assets with full valuation allowance		70.0
Deferred Tax Asset Realization Remote | State and Local Jurisdiction
Tax Credit Carryforward [Line Items]
Deferred tax assets with full valuation allowance		100.0
Deferred Tax Asset, Currency Translation And Other
Tax Credit Carryforward [Line Items]
Net increase (decrease) in valuation allowance		$ 19.4
Valuation Allowance, Federal Loss Carryforwards | Domestic
Tax Credit Carryforward [Line Items]
Valuation allowance	$ 31.4