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Equity (Narrative) (Details) - USD ($) |  | 3 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Feb. 22, 2024 | Mar. 31, 2024 | Mar. 31, 2023 | Feb. 23, 2024 | Mar. 15, 2024 | Dec. 31, 2023 | Dec. 01, 2023 | Jun. 15, 2023
Preferred Stock, Shares Authorized |  | 20,000,000 |  |  |  | 20,000,000 |  |
Preferred Stock, Shares Outstanding |  | 0 |  |  |  | 40,000 |  |
Preferred Stock, Par or Stated Value Per Share |  | $ 0.01 |  |  | $ 25,000 | $ 0.01 | $ 0.01 |
Preferred Stock Shares Redeemed |  | 0 |  |  |  |  |  |
Common Stock, Shares, Issued |  |  |  |  |  |  | 33,898,837 |
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share |  | $ 25.76 |  | $ 25.78 |  |  |  |
Preferred Stock, Liquidation Preference Per Share |  |  |  |  |  |  |  | $ 1,000
Preferred Stock Redemption Premium |  | $ 14,000,000.0 | $ 0 |  |  |  |  |
Pension Plan |  |  |  |  |  |  |  |
Defined Benefit Plan, Plan Assets, Contributions by Employer |  | 700,000 | 1,200,000 |  |  |  |  |
Other Postretirement Benefit Plan |  |  |  |  |  |  |  |
Defined Benefit Plan, Plan Assets, Contributions by Employer |  | 5,400,000 | $ 5,600,000 |  |  |  |  |
At The Market Program |  |  |  |  |  |  |  |
Common Stock Aggregate Sale Price | $ 900,000,000 | 199,800,000 |  |  |  |  |  |
ATM Program Equity Remaining Available for Issuance |  | $ 700.0 |  |  |  |  |  |
Forward February 23 |  |  |  |  |  |  |  |
Forward Contract Indexed to Issuer's Equity, Shares |  |  |  | 7,757,951 |  |  |  |
Series A Preferred Stock |  |  |  |  |  |  |  |
Preferred Stock, Shares Outstanding |  |  |  |  |  |  |  | 400,000
Preferred Stock, Redemption Amount |  |  |  |  |  |  |  | $ 400,000,000
Preferred Stock, Dividends Per Share, Declared |  | $ 0 | $ 28.25 |  |  |  |  |
Series B Preferred Stock |  |  |  |  |  |  |  |
Preferred Stock, Dividends Per Share, Declared |  | $ 406.25 | $ 812.50 |  |  |  |  |
Preferred Stock Redemption Premium |  | $ 14,000,000 |  |  |  |  |  |
Series B-1 Preferred Stock |  |  |  |  |  |  |  |
Preferred Stock, Par or Stated Value Per Share |  |  |  |  | $ 0.01 |  |  |
Preferred Stock, Redemption Amount |  |  |  |  | $ 500,000,000 |  |  |
Preferred Stock, Shares Issued |  | 20,000 |  |  | 20,000 |  |  |

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