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Related-Party Transactions - Additional Information (Detail) |  |  |  | 1 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | ---
Jul. 14, 2020 | Feb. 20, 2020 $ / shares shares | Jan. 08, 2019 | Jul. 31, 2015 | Dec. 31, 2020 USD ($) officer | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |
Number of executive officers | officer |  |  |  |  |  | 2 |  |
Due to adviser and administrator | [1] |  |  |  |  | $ 2,960,000 | $ 2,904,000 |
Annual base management fee, in percentage of stockholders' equity, adjusted to unrealized gains or losses (as percent) |  | 0.425% |  | 1.50% |  |  |  |
Quarterly base management fee, in percentage of stockholders' equity, adjusted to unrealized gains or losses (as percent) |  | 0.10625% |  | 0.375% |  |  |  |
Base management fee | [2] |  |  |  |  | $ 5,648,000 | 5,174,000 | $ 5,054,000
Pre-incentive quarterly fee FFO in percentage of common stockholders' equity that will reward the adviser (as percent) |  |  |  |  |  | 2.00% |  |
Pre-incentive annual fee FFO in percentage of common stockholders' equity that will reward the adviser (as percent) |  |  |  |  |  | 8.00% |  |
Amount to be paid to adviser in percentage of pre-incentive fee condition one (as percent) |  |  |  |  |  | 15.00% |  |
Incentive fee | [2] |  |  |  |  | $ 4,301,000 | 3,688,000 | 3,042,000
Portion of incentive fee waived |  |  |  |  |  | $ 0 | 0 | 0
Capital gains-based incentive fee percentage (as percent) |  |  |  |  |  | 15.00% |  |
Capital gain fee |  |  |  |  |  | $ 0 | 0 | 0
Notice period for termination of agreement without cause |  |  |  |  |  | 120 days |  |
Percentage of independent directors to terminate the Amended Advisory Agreement (as a percent) |  |  |  |  | 66.67% |  |  |
Termination fee payable (as percent) |  |  |  |  | 200.00% |  |  |
Payment period for termination of agreement |  |  |  |  |  | 24 months |  |
Notice period for termination of agreement with cause |  |  |  |  |  | 30 days |  |
Administration fee | [2] |  |  |  |  | $ 1,598,000 | 1,690,000 | 1,605,000
Fees paid |  |  |  |  |  | $ 100,000 | $ 200,000 | $ 100,000
Financing fee on total secured mortgages (as percent) |  |  |  |  |  | 0.25% | 0.20% | 0.11%
Selling commissions (as percent) |  |  | 6.00% |  |  |  |  |
Dealer management fee (as percent) |  |  | 3.00% |  |  |  |  |
Dealer Management Agreement | Series F Cumulative Redeemable Preferred Stock | Preferred Stock |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |
Preferred stock, dividend rate (as percent) |  |  | 6.00% |  |  |  |  |
Redeemable preferred stock, shares authorized (in shares) | shares |  |  | 20,000,000 |  |  |  |  |
Redeemable preferred stock, par value (in dollars per share) | $ / shares |  |  | $ 0.001 |  |  |  |  |
Redeemable preferred stock, dividend reinvestment plan, shares authorized (in shares) | shares |  |  | 6,000,000 |  |  |  |  |
Minimum |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |
Percentage of the amount of the mortgage (as percent) |  |  |  |  |  | 0.15% |  |
Maximum |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |
Percentage of the amount of the mortgage (as percent) |  |  |  |  |  | 1.00% |  |
[1] | Refer to Note 2 “Related-Party Transactions”
[2] | Refer to Note 2 “Related-Party Transactions”

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