Annual report pursuant to Section 13 and 15(d)

Income Taxes - Narrative (Details)

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Income Taxes - Narrative (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Operating Loss Carryforwards [Line Items]        
Percentage of Net Operating Losses Limited upon Tax Reform Enactment 80.00%      
Tax Cuts And Jobs Act Of 2017, provisional income tax expense $ 0.1      
Undistributed earnings of foreign subsidiaries 11.3      
Future annual required taxable income for state tax purposes 69.6      
Unrecognized tax benefits 1.6 $ 4.8 $ 5.0 $ 81.9
Unrecognized tax benefit that would impact effective tax rate, net of federal tax benefits 0.1      
Decrease resulting from prior period tax positions 3.4 0.6 $ 78.2  
Decrease to prior period tax positions related to Tax Cuts and Jobs Act of 2017   $ 0.5    
Discontinued Operations, Disposed of by Sale        
Operating Loss Carryforwards [Line Items]        
Decrease resulting from prior period tax positions $ 3.1