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Equity and Mezzanine Equity - Additional Information (Detail) - USD ($) |  | 9 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Feb. 20, 2020 | Sep. 30, 2020 | Feb. 19, 2020 | Jan. 29, 2020 | Dec. 31, 2019 | Jan. 11, 2019
Class of Stock [Line Items] |  |  |  |  |  |
Common stock, shares outstanding (in shares) | 60,290,000 | 34,183,869 | 86,290,000 |  | 32,593,651 |
Series D Preferred Stock |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Temporary equity, contract terms, minimum vote needed to trigger change in control from tender offer (as percent) |  | 90.00% |  |  |  |
Preferred Stock | Series D Preferred Stock |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Redeemable preferred stock, dividend rate percentage (as percent) |  | 7.00% |  |  |  |
Preferred Stock | Series E Preferred Stock |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Redeemable preferred stock, dividend rate percentage (as percent) |  | 6.625% |  |  |  |
Preferred Stock | Series F Preferred Stock |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Redeemable preferred stock, shares issued (in shares) |  | 45,102 |  |  |  |
Consideration received |  | $ 1,000,000.0 |  |  |  |
Maximum remaining capacity to sell common stock under open market sale agreement |  | $ 635,400,000 |  |  |  |
Redeemable preferred stock, dividend rate percentage (as percent) | 6.00% |  |  |  |  |
Redeemable preferred stock, shares authorized (in shares) | 26,000,000 |  |  |  |  |
Baird, Goldman Sachs, Stifel, Fifth Third, and U.S. Bancorp Investments, Inc. | Preferred Stock | Series E Preferred Stock |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Redeemable preferred stock, shares issued (in shares) |  | 239,399 |  |  |  |
Consideration received |  | $ 5,600,000 |  |  |  |
Maximum aggregate sales price of shares to be issued under open market sale agreement |  | 100,000,000.0 |  |  |  |
Maximum remaining capacity to sell common stock under open market sale agreement |  | $ 94,400,000 |  |  |  |
Common Stock ATM Program | Baird, Goldman Sachs, Stifel, Fifth Third, and U.S. Bancorp Investments, Inc. | Common Stock |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Redeemable preferred stock, shares issued (in shares) |  | 1,600,000 |  |  |  |
Consideration received |  | $ 32,400,000 |  |  |  |
Maximum aggregate sales price of shares to be issued under open market sale agreement |  | 250,000,000.0 |  |  |  |
Maximum remaining capacity to sell common stock under open market sale agreement |  | 204,600,000 |  |  |  |
2019 Universal Shelf |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Universal registration statement, amount authorized |  | 399,500,000 |  |  |  | $ 500,000,000.0
2020 Universal Shelf |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Universal registration statement, amount authorized |  | $ 798,900,000 |  | $ 800,000,000.0 |  |
2020 Universal Shelf | Preferred Stock | Series F Preferred Stock |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Universal registration statement, amount authorized |  |  |  | $ 636,500,000 |  |

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