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Debt - Narrative (Details) |  |  | 1 Months Ended | 3 Months Ended | 6 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Mar. 15, 2022 USD ($) | Mar. 10, 2022 USD ($) deferral_period | Jun. 30, 2017 USD ($) | Jun. 30, 2024 USD ($) | Jun. 30, 2023 USD ($) | Jun. 30, 2024 USD ($) | Jun. 30, 2023 USD ($) | Dec. 31, 2023 USD ($) | Mar. 16, 2022 USD ($) | Feb. 15, 2022 USD ($) | Sep. 22, 2020 | Feb. 28, 2015 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Long-Term Debt |  |  |  | $ 1,390,400,000 |  | $ 1,390,400,000 |  | $ 1,389,200,000 |  |  |  |
Interest and other expenses |  |  |  | 13,900,000 | $ 14,000,000.0 | 27,900,000 | $ 28,100,000 |  |  |  |  |
Interest paid, including capitalized interest, operating and investing activities |  |  |  | $ 7,300,000 | $ 2,500,000 | $ 27,300,000 | $ 27,300,000 |  |  |  |  |
Senior Notes | Senior Notes, 4.35 Percent Due February 15, 2025 |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Stated interest rate |  |  |  | 4.35% |  | 4.35% |  |  |  |  |  |
Long-term debt, gross |  |  |  | $ 450,000,000.0 |  | $ 450,000,000.0 |  |  |  |  |  |
Face amount of debt |  |  |  |  |  |  |  |  |  |  |  | $ 250,000,000.0
Increase in senior notes |  |  | $ 200,000,000.0 |  |  |  |  |  |  |  |  |
Long-Term Debt |  |  |  | $ 0 |  | $ 0 |  | 449,600,000 |  |  |  |
Senior Notes | Senior Notes, 2.400 Percent Due September 30, 2030 |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Stated interest rate |  |  |  | 2.40% |  | 2.40% |  |  |  |  |  |
Long-term debt, gross |  |  |  | $ 400,000,000.0 |  | $ 400,000,000.0 |  |  |  |  |  |
Face amount of debt |  |  |  | 395,800,000 |  | 395,800,000 |  |  |  |  |  |
Long-Term Debt |  |  |  | $ 397,300,000 |  | $ 397,300,000 |  | 397,000,000.0 |  |  |  |
Effective interest rate |  |  |  | 2.52% |  | 2.52% |  |  |  |  |  |
Senior Notes | Senior Notes, 3.800 Percent Due February 23, 2033 |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Stated interest rate |  |  |  | 3.80% |  | 3.80% |  |  |  |  |  |
Long-term debt, gross |  |  |  |  |  |  |  |  |  | $ 400,000,000 |  |
Long-Term Debt |  |  |  | $ 396,200,000 |  | $ 396,200,000 |  | 396,000,000.0 |  | $ 395,100,000 |  |
Effective interest rate |  |  |  |  |  |  |  |  |  |  | 3.95% |
Junior Subordinated Debt [Member] | 5.875% Fixed-Rate Reset Junior Subordinated Debentures due 2062 |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Stated interest rate |  |  |  | 5.875% |  | 5.875% |  |  |  |  |  |
Long-term debt, gross |  | $ 150,000,000 |  |  |  |  |  |  |  |  |  |
Long-Term Debt |  | $ 144,700,000 |  | $ 147,100,000 |  | $ 147,100,000 |  | $ 146,600,000 |  |  |  |
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 | $ 600,000,000.0 |  |  | 458,000,000.0 |  | 458,000,000.0 |  |  | $ 800,000,000.0 |  |  |
Increase in revolving credit borrowing capacity | $ 200,000,000.0 |  |  |  |  |  |  |  |  |  |  |
Line of credit facility, amount outstanding |  |  |  | $ 0 |  | $ 0 |  |  |  |  |  |

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- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -SubTopic 10 -Topic 210 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481139/470-20-50-4 + Details
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