Annual report pursuant to Section 13 and 15(d)

Income Taxes (Narrative) (Details)

v3.8.0.1
Income Taxes (Narrative) (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Dec. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Operating Loss Carryforwards [Line Items]          
Effective income tax rate     (2.00%) 35.00% 38.00%
Corporate tax rate     35.00%    
Tax Cuts and Jobs Act of 2017, income tax benefit $ 47.7   $ 47.7    
Agreement to Allocate Consolidated Income Tax Liability and Benefits     39.3 $ 26.2 $ 19.2
Recognized interest or penalties 0.0   0.0    
State [Member]          
Operating Loss Carryforwards [Line Items]          
State operating loss carryforwards $ 240.2   $ 240.2    
Scenario, Plan [Member]          
Operating Loss Carryforwards [Line Items]          
Corporate tax rate   21.00%