Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2017	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net benefit related to U.S. Tax Reform	$ 29.9			$ 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
Tax Credit Carryforward, Valuation Allowance	946.7			946.7
Tax benefit due to tax planning strategies		$ 29.3	$ 18.7
Deferred tax assets, net operating loss	2,022.1			2,022.1	$ 2,033.0
Valuation allowance	3,217.7			3,217.7	3,296.0
Foreign tax credit carryforwards	912.6			912.6
Change in deferred tax liability associated with undistributed earnings				(64.4)
Deferred tax liabilities, undistributed foreign earnings	22.6			22.6
Undistributed earnings of foreign subsidiaries	1,500.0			1,500.0
Net increase (decrease) in valuation allowance						$ 669.7
Minimum tax credit carryforwards	35.9			35.9
Deferred Tax Assets, Tax Credit Carryforwards, Research	19.6			19.6
Total gross unrecognized tax benefits	48.6		$ 53.0	48.6	58.7	53.0	$ 56.7
Unrecognized tax benefits that would impact effective tax rate	46.0			46.0
Accrued interest and penalties	9.9			9.9	9.3
Expense for interest and penalties					$ 2.5	$ 2.8
Operating Loss Carryforwards, Valuation Allowance	1,961.5			1,961.5
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	1,922.2			$ 1,922.2
Newly enacted tax rate				21.00%
State and Local Jurisdiction [Member]
Operating loss carryforwards	1,512.4			$ 1,512.4
Operating Loss Carryforwards, Valuation Allowance	99.9			99.9
Deferred tax assets, state tax loss carryforwards	99.9			99.9
Foreign [Member]
Operating Loss Carryforwards, Valuation Allowance	1,861.6			1,861.6
Beginning [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Lower Bound	5.0			$ 5.0
Beginning [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Expiration Dates				Jan. 01, 2018
Beginning [Member] | Foreign [Member]
Tax Credit Carryforward, Expiration Date				Jan. 01, 2018
Operating Loss Carryforwards, Expiration Dates				Jan. 01, 2018
Ending [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Lower Bound	8.0			$ 8.0
Ending [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Expiration Dates				Dec. 31, 2037
Ending [Member] | Foreign [Member]
Tax Credit Carryforward, Expiration Date				Dec. 31, 2027
Operating Loss Carryforwards, Expiration Dates				Dec. 31, 2034
Research Tax Credit Carryforward [Member] | Beginning [Member]
Tax Credit Carryforward, Expiration Date				Jan. 01, 2027
Research Tax Credit Carryforward [Member] | Ending [Member]
Tax Credit Carryforward, Expiration Date				Dec. 31, 2037
Investment Tax Credit Carryforward [Member]
Tax credit carryforward	12.9			$ 12.9
Investment Tax Credit Carryforward [Member] | Beginning [Member]
Tax Credit Carryforward, Expiration Date				Jan. 01, 2018
Investment Tax Credit Carryforward [Member] | Ending [Member]
Tax Credit Carryforward, Expiration Date				Dec. 31, 2032
Foreign [Member]
Operating loss carryforwards	7,448.4			$ 7,448.4
Operating loss carryforwards, not subject to expiration	7,060.4			7,060.4
Operating loss carryforwards, subject to expiration	388.0			$ 388.0
EMEA [Member]
Net increase (decrease) in valuation allowance	$ 25.5