Income Taxes (NOL and Tax Credit Carryforwards) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
Deferred income taxes	$ (28.7)	$ (273.8)	$ (245.1)
State
Operating Loss Carryforwards [Line Items]
NOL carryforwards	114.2
NOL carryforwards for which deferred tax assets have not been recorded	476.4
Research
Operating Loss Carryforwards [Line Items]
Credit carryforwards	16.8
Credit carryforwards for which deferred tax assets have not been recorded	4.0
State NOL Expiring 2016 through 2035 | State
Operating Loss Carryforwards [Line Items]
NOL carryforwards	$ 883.5