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Debt (Tables) | 9 Months Ended
--- | ---
Sep. 30, 2025
Debt Disclosure [Abstract] |
Schedule of Debt | The following table summarizes the Company’s Debt:
| December 31, 2024 |  | September 30, 2025
Senior bank debt | $— |  | $100.0
Senior notes | 1,092.1 |  | 743.1
Junior subordinated notes | 1,189.0 |  | 1,189.3
Junior convertible securities | 339.1 |  | 339.2
Debt | $2,620.2 |  | $2,371.6
Schedule of Principal Terms of Senior and Junior Subordinated Notes | The principal terms of the senior notes outstanding as of September 30, 2025 are presented and described below:
|  | 2030 Senior Notes |  | 2034 Senior Notes
Issue date |  | June 2020 |  | August 2024
Maturity date |  | June 2030 |  | August 2034
Par value (in millions) |  | $350.0 |  | $400.0
Stated coupon |  | 3.30% |  | 5.50%
Coupon frequency |  | Semi-annually |  | Semi-annually
Call price |  | As defined |  | As defined
As of September 30, 2025, the Company had junior subordinated notes outstanding, the respective principal terms of which are presented and described below:
|  | 2059 Junior Subordinated Notes |  | 2060 Junior Subordinated Notes |  | 2061 Junior Subordinated Notes |  | 2064 Junior Subordinated Notes
Issue date |  | March 2019 |  | September 2020 |  | July 2021 |  | March 2024
Maturity date |  | March 2059 |  | September 2060 |  | September 2061 |  | March 2064
Par value (in millions) |  | $300.0 |  | $275.0 |  | $200.0 |  | $450.0
Stated coupon |  | 5.875% |  | 4.75% |  | 4.20% |  | 6.75%
Coupon frequency |  | Quarterly |  | Quarterly |  | Quarterly |  | Quarterly
Call price |  | As defined |  | As defined |  | As defined |  | As defined
NYSE Symbol |  | MGR |  | MGRB |  | MGRD |  | MGRE
Schedule of Convertible Securities | The fol lowing table presents interest expense recorded in connection with the junior convertible securities:
|  | For the Three Months Ended September 30, |  | For the Nine Months Ended September 30,
|  | 2024 |  | 2025 |  | 2024 |  | 2025
Contractual interest expense |  | $4.4 |  | $4.4 |  | $13.2 |  | $13.2
Amortization of debt issuance costs |  | 0.1 |  | 0.1 |  | 0.2 |  | 0.2
Total |  | $4.5 |  | $4.5 |  | $13.4 |  | $13.4
Effective interest rate |  | 5.21% |  | 5.21% |  | 5.21% |  | 5.21%

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