Debt - Narrative (Details)			1 Months Ended	3 Months Ended
	Mar. 10, 2022 USD ($) deferral_period	Jun. 04, 2019 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Feb. 15, 2022 USD ($)	Sep. 22, 2020 USD ($)	Jun. 08, 2018 USD ($)	Feb. 28, 2015 USD ($)
Debt Instrument [Line Items]
Long-Term Debt				$ 1,389,800,000		$ 1,389,200,000
Interest and other expenses				14,000,000	$ 14,100,000
Interest paid, including capitalized interest, operating and investing activities				20,000,000	$ 24,800,000
Derivative, Gain on Derivative				5,900,000
Senior Notes, 2.400 Percent Due September 30, 2030
Debt Instrument [Line Items]
Long-Term Debt								$ 395,800,000
Senior Notes, 3.800 Percent Due February 23, 2033
Debt Instrument [Line Items]
Long-Term Debt							$ 395,100,000
5.875% Fixed-Rate Reset Junior Subordinated Debentures due 2062
Debt Instrument [Line Items]
Long-Term Debt	$ 144,700,000
Senior Notes | Senior Notes, 4.35 Percent Due February 15, 2025
Debt Instrument [Line Items]
Long-Term Debt				$ 0		449,600,000
Stated interest rate				4.35%
Long-term debt, gross				$ 450,000,000
Face amount of debt										$ 250,000,000
Increase in senior notes			$ 200,000,000
Senior Notes | Senior Notes, 2.400 Percent Due September 30, 2030
Debt Instrument [Line Items]
Long-Term Debt				397,100,000		397,000,000.0
Stated interest rate								2.40%
Long-term debt, gross				400,000,000
Effective interest rate								2.52%
Senior Notes | Senior Notes, 3.800 Percent Due February 23, 2033
Debt Instrument [Line Items]
Long-Term Debt				396,100,000		396,000,000.0
Stated interest rate							3.80%
Long-term debt, gross				400,000,000
Effective interest rate								3.95%
Senior Notes | 5.875% Fixed-Rate Reset Junior Subordinated Debentures due 2062
Debt Instrument [Line Items]
Long-Term Debt				146,900,000		$ 146,600,000
Long-term debt, gross				150,000,000
Junior Subordinated Debt [Member] | 5.875% Fixed-Rate Reset Junior Subordinated Debentures due 2062
Debt Instrument [Line Items]
Stated interest rate	5.875%
Debt Instrument, Basis Spread on Variable Rate	4.14%
Debt Instrument, Interest Deferrals, Number Of Deferral Periods | deferral_period	1
Debt Instrument, Interest Deferrals, Period	5 years
Revolving Credit Facility | Notes Payable under Revolving Credit Agreement | Second Amended and Restated Credit Agreement
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 800,000,000		424,000,000					$ 600,000,000
Increase in revolving credit borrowing capacity		$ 200,000,000
Line of credit facility, amount outstanding				$ 0