Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017		Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Income tax benefit (provision)	$ 54.0	$ 133.0	$ 126.0	$ 124.0	$ 1,978.0	[1]	$ 89.0		$ 153.0		$ (66.0)		$ 437.0	$ 2,154.0	[1]	$ (3.0)
Provisional tax included in income tax expense from normal operations													412.0
Provisional tax included in income tax expense from change in tax rate													25.0
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Change in Tax Rate, Deferred Tax Asset, Provisional Income Tax Expense (Benefit)														347.0
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Transition Tax for Accumulated Foreign Earnings, Provisional Income Tax Expense (Benefit)														1,100.0
Reduction of tax benefit due to foreign exchange losses and translation adjustments														35.0
Tax Cuts And Jobs Act Of 2017 Global Intangible Low-Taxed Income Provisional Tax (GILTI tax)													55.0
Tax Cuts And Jobs Act Of 2017 Foreign Derived Intangible Income Provisional Tax (FDII benefit)													10.0
Tax Cuts And Jobs Act Of 2017 Provisional Tax From Truing Up Toll Charge													20.0
Tax Cuts and Jobs Act of 2017, Net Operating Loss Carryforward	35.0												$ 35.0
Tax Cuts and Jobs Act of 2017, Net Operating Loss Carryback, Period													2 years
Tax Cuts and Jobs Act of 2017, Net Operating Loss Carryforward, Period													20 years
Tax Cuts and Jobs Act of 2017, Foreign Tax Credit Carryforward	22.0												$ 22.0
Deferred tax assets valuation allowance	317.0				456.0								317.0	456.0
Unrecognized tax benefits that would impact effective tax rate	263.0				97.0								$ 263.0	$ 97.0		$ 92.0
Percentage of U.S. Subsidiaries Join in Filing of Consolidated United States Federal Income Tax Returns													80.00%
Statutory U.S. income tax rate													21.00%	35.00%		35.00%
Undistributed earnings of foreign subsidiaries	1,500.0				$ 15,400.0								$ 1,500.0	$ 15,400.0
Unremitted foreign earnings, percent														94.00%
Historic foreign earnings to be indefinitely reinvested, percent														6.00%
Foreign earnings repatriated													4,200.0
Additional income tax as result of agreement with IRS				172.0
Interest expense, net of tax benefit				$ 12.0
National Tax Service of Korea [Member]
Income tax expected refund as result of agreement with tax authority	$ 425.0												$ 425.0
Foreign Tax Authority [Member] | National Tax Agency, Japan [Member] | Tax Year 2011 [Member]
Open tax year													2011
Foreign Tax Authority [Member] | National Tax Administration of Taiwan [Member] | Tax Year 2012 [Member]
Open tax year													2012
Foreign Tax Authority [Member] | National Tax Service of Korea [Member] | Tax Year 2012 [Member]
Open tax year													2012
Minimum [Member]
US Statutes of Limitations Period													3 years
Foreign Statutes of Limitations Period													3 years
Maximum [Member]
US Statutes of Limitations Period													5 years
Foreign Statutes of Limitations Period													10 years
Accounting Standards Update 2016-16 [Member]
Cumulative tax benefits in beginning retained earnings													$ 5.0

[1] In December 2017, the U.S. enacted the 2017 Tax Act which resulted in significant changes to our provision for income taxes during the fourth quarter of 2017. Refer to Note 4 (Income Taxes) to the Consolidated Financial Statements for additional information.