Annual report pursuant to Section 13 and 15(d)

Income Taxes, Tax Credits and Unrecognized Tax Benefits (Details)

v3.20.4
Income Taxes, Tax Credits and Unrecognized Tax Benefits (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Income Tax Disclosure [Abstract]      
Gross Unrecognized Tax Benefits, Including Interest $ 4.1 $ 3.9 $ 2.3
Reconciliation of the total amounts of unrecognized tax benefits [Roll Forward]      
Balance at January 1 3.7 2.3 2.1
Gross Increases - Tax Positions Prior Periods 0.1 2.0 0.6
Gross Decreases - Tax Positions Prior Periods 0.0 (0.8) (0.7)
Gross Increases - Current Period Tax Positions 0.6 0.4 0.4
Decreases - Settlements with Taxing Authorities (0.1) 0.0 (0.1)
Reductions - Lapse of Statute of Limitations (0.6) (0.2) 0.0
Balance at December 31 3.7 3.7 $ 2.3
Possible Decrease in Unrecognized Tax Benefits in 2017 0.5    
Tax Credit Carryforward [Line Items]      
Tax Credit Carryforward, Amount 51.4    
Tax Credit Carryforwards 51.1 $ 71.8  
Tax Credit Carryforward, Expiration Date 51.4    
General Business Credits [Member]      
Tax Credit Carryforward [Line Items]      
Tax Credit Carryforwards 7.5    
State Tax Credits [Member]      
Tax Credit Carryforward [Line Items]      
Tax Credit Carryforwards $ 43.9