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Description of Business - Stock Issuance (Details) - shares |  |  | 6 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Apr. 09, 2021 | Dec. 15, 2020 | Jun. 30, 2021 | Dec. 31, 2020
8.625% Series A Cumulative, Perpetual Preferred Stock |  |  |  |
Stock |  |  |  |
Preferred stock, dividend rate (as a percent) |  | 8.625% | 8.625% | 8.625%
8.375% Series B Cumulative, Perpetual Preferred Stock |  |  |  |
Stock |  |  |  |
Preferred stock, dividend rate (as a percent) | 8.375% |  | 8.375% | 8.375%
Depositary share's fractional interest in share of preferred stock | 0.001 |  |  |
8.375% Series B Cumulative, Perpetual Preferred Stock | Public Offering of Depository Shares and Series B Preferred Shares |  |  |  |
Stock |  |  |  |
Preferred stock, dividend rate (as a percent) |  |  | 8.375% |
Depositary share's fractional interest in share of preferred stock |  |  | 0.001 |

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