Annual report pursuant to Section 13 and 15(d)

Income Taxes (Narrative) (Details)

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Income Taxes (Narrative) (Details) - USD ($)
3 Months Ended 12 Months Ended
Dec. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Operating Loss Carryforwards [Line Items]        
Effective income tax rate   25.00% (2.00%) 35.00%
Corporate tax rate   21.00% 35.00%  
Tax Cuts and Jobs Act of 2017, income tax benefit $ 47,700,000      
Agreement to Allocate Consolidated income tax liability and benefits payments   $ 23,100,000 $ 39,300,000 $ 26,200,000
Recognized interest or penalties   0    
State [Member]        
Operating Loss Carryforwards [Line Items]        
State operating loss carryforwards   $ 224,300,000