Debt - Long Term Debt (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Mar. 10, 2022	Feb. 15, 2022	Sep. 22, 2020
Debt Instrument [Line Items]
Long-term Debt	$ 1,388.1	$ 1,386.9
Derivative, Gain (Loss) on Derivative, Net	0.5
Gain (Loss) on Derivative Instruments, Net, Pretax	0.3
2.400% Senior Notes due September 30, 2030
Debt Instrument [Line Items]
Long-term Debt					$ 395.8
Senior Notes, 3.800 Percent Due February 23, 2033
Debt Instrument [Line Items]
Long-term Debt				$ 395.1
5.875% Fixed-Rate Reset Junior Subordinated Debentures due 2062
Debt Instrument [Line Items]
Long-term Debt			$ 144.7
Senior Notes | 4.350% Senior Notes due February 15, 2025
Debt Instrument [Line Items]
Long-term Debt	$ 449.5	449.3
Stated interest rate	4.35%
Senior Notes | 2.400% Senior Notes due September 30, 2030
Debt Instrument [Line Items]
Long-term Debt	$ 396.8	396.6
Stated interest rate					2.40%
Senior Notes | Senior Notes, 3.800 Percent Due February 23, 2033
Debt Instrument [Line Items]
Long-term Debt	395.7	395.5
Stated interest rate				3.80%
Senior Notes | Senior Notes, 5.875 Percent Due March 15, 2062
Debt Instrument [Line Items]
Long-term Debt	$ 146.1	$ 145.5
Junior Debt | Senior Notes, 5.875 Percent Due March 15, 2062
Debt Instrument [Line Items]
Stated interest rate			5.875%