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Shareholders' Equity (Narrative) (Detail) $ / shares in Units, $ in Millions | 1 Months Ended | 12 Months Ended
--- | --- | ---
Jan. 31, 2023 $ / shares | Jun. 30, 2022 USD ($) shares | May 31, 2020 USD ($) $ / shares shares | Jun. 30, 2015 USD ($) $ / shares shares | Dec. 31, 2023 $ / shares | Dec. 31, 2022 $ / shares | Dec. 31, 2021 $ / shares | Dec. 31, 2020 $ / shares
Temporary Equity [Line Items] |  |  |  |  |  |  |  |
Cash dividends declared per common share (usd per share) |  |  |  |  |  | $ 1.36 | $ 1.24 | $ 1.12
Forecast |  |  |  |  |  |  |  |
Temporary Equity [Line Items] |  |  |  |  |  |  |  |
Cash dividends declared per common share (usd per share) |  |  |  |  | $ 1.60 |  |  |
Subsequent Event |  |  |  |  |  |  |  |
Temporary Equity [Line Items] |  |  |  |  |  |  |  |
Cash dividends declared per common share (usd per share) | $ 0.40 |  |  |  |  |  |  |
Series D Preferred Stock |  |  |  |  |  |  |  |
Temporary Equity [Line Items] |  |  |  |  |  |  |  |
Sale of stock (in shares) | shares |  |  |  | 5,000,000 |  |  |  |
Sale of stock, proceeds | $ |  |  |  | $ 125.0 |  |  |  |
Preferred stock, liquidation value per share (usd per share) |  |  |  | $ 25 |  | $ 25 | 25 |
Preferred stock, dividend rate |  |  |  | 6.50% |  |  |  |
Series D Preferred Stock | London Interbank Offered Rate (LIBOR) |  |  |  |  |  |  |  |
Temporary Equity [Line Items] |  |  |  |  |  |  |  |
Preferred stock, dividend rate, variable spread |  |  |  | 4.06% |  |  |  |
Series D Preferred Stock | Secured Overnight Financing Rate (SOFR) |  |  |  |  |  |  |  |
Temporary Equity [Line Items] |  |  |  |  |  |  |  |
Preferred stock, dividend rate, variable spread |  |  |  |  |  | 4.06% |  |
Dividend rate, spread on floating rate |  |  |  |  |  | 0.0026161 |  |
Series E Preferred Stock |  |  |  |  |  |  |  |
Temporary Equity [Line Items] |  |  |  |  |  |  |  |
Sale of stock (in shares) | shares |  |  | 11,500 |  |  |  |  |
Sale of stock, proceeds | $ |  |  | $ 287.5 |  |  |  |  |
Preferred stock, liquidation value per share (usd per share) |  |  | $ 25,000 |  |  | $ 25,000 | $ 25,000 |
Preferred stock, dividend rate |  |  | 6.875% |  |  |  |  |
Series E Preferred Stock | US Treasury (UST) Interest Rate |  |  |  |  |  |  |  |
Temporary Equity [Line Items] |  |  |  |  |  |  |  |
Dividend rate, spread on floating rate |  |  | 0.06507 |  |  |  |  |
Depositary shares |  |  |  |  |  |  |  |
Temporary Equity [Line Items] |  |  |  |  |  |  |  |
Sale of stock (in shares) | shares |  |  | 11,500,000 |  |  |  |  |
Ratio of preferred stock to depositary shares |  |  | 0.001 |  |  |  |  |
Public Offering | Common stock |  |  |  |  |  |  |  |
Temporary Equity [Line Items] |  |  |  |  |  |  |  |
Sale of stock (in shares) | shares |  | 3,450,000 |  |  |  |  |  |
Sale of stock, proceeds | $ |  | $ 285.7 |  |  |  |  |  |

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