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Debt and Financing Arrangements - Narrative (Details) - USD ($)
Apr. 02, 2021
Mar. 12, 2021
Mar. 31, 2021
Dec. 31, 2020
Debt Instrument [Line Items]        
Short-term debt outstanding     $ 360,800,000 $ 153,100,000
2021 Credit Facility | 2021 Credit Facility        
Debt Instrument [Line Items]        
Debt term   5 years    
Line of credit, maximum borrowing capacity   $ 750,000,000    
Line of credit facility, accordion feature, higher borrowing capacity option   1,250,000,000    
Maximum subsidiary borrowings   $ 75,000,000    
Line of credit facility covenants maximum debt to capitalization percentage   65.00%    
2021 Credit Facility | Letter of Credit        
Debt Instrument [Line Items]        
Line of credit, maximum borrowing capacity   $ 50,000,000    
Senior Notes | Senior notes at 2.300%        
Debt Instrument [Line Items]        
Interest rate, stated percentage   2.30% 2.30%  
Face amount   $ 300,000,000    
Proceeds from offering   $ 295,500,000    
Senior Notes | Senior notes at 3.625%        
Debt Instrument [Line Items]        
Interest rate, stated percentage     3.625%  
Senior Notes | Senior notes at 3.625% | Subsequent Event        
Debt Instrument [Line Items]        
Interest rate, stated percentage 3.625%      
Debt instrument, amount paid $ 300,000,000      
Loss on extinguishment of debt 16,800,000      
Loss on extinguishment of debt, cash premium $ 16,000,000.0