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Debt - Additional Information (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Debt Instrument [Line Items]        
Cash payments paid for interest     $ 56.9 $ 53.4
Amortization of treasury lock settlements   $ 1.3   3.9
Amortization of financing costs $ 0.5 $ 0.7 1.5 $ 2.1
Senior Notes | Fixed-Rate Senior Notes        
Debt Instrument [Line Items]        
Book value of fixed rate debt 2,493.5   2,493.5  
Long-term debt (fixed-rate debt), fair value $ 2,776.3   $ 2,776.3