Income Taxes (Operating Loss and Tax Credit Carryforwards) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
U.S. Federal net operating loss carryforwards	$ 589.0	$ 528.5
United States [Member]
U.S. Federal net operating loss carryforwards	680.0
U.S. credit carryforwards	121.5
State and Local Jurisdiction [Member]
U.S. credit carryforwards	34.7
U.S. State net operating loss carryforwards	3,484.2
Non-U.S. [Member]
Non-U.S. net operating loss carryforwards	752.0
Non-U.S. credit carryforwards	$ 8.0