Debt - Additional Information (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($)
Standby Letters of Credit
Debt Additional Information
Letters of Credit Outstanding, Amount	$ 0.0
Three-year Unsecured Revolving Credit Facility
Debt Additional Information
Letters of Credit Outstanding, Amount	0.0
4.125% Senior Notes due 2051 | Senior Notes
Debt Additional Information
Debt Instrument, Face Amount	600.0
Notes 4.500 Due 2025
Debt Additional Information
Debt Instrument, Repurchased Face Amount	500.0
Cost Related to Early Retirement of Debt	$ 67.3