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Shareholders' Equity - Additional Information (Detail) - USD ($) $ in Thousands | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Jan. 28, 2021 | Mar. 31, 2020 | Aug. 13, 2018
Shareholders' Equity [Line Items] |  |  |  |  |  |
Authorized and unissued common shares reserved for issuance (in shares) | 300,000,000 | 300,000,000 |  |  |  |
Common shares purchase price as percentage of fair market value | 95.00% |  |  |  |  |
Maximum value of shares purchased as percentage of employee compensation | 10.00% |  |  |  |  |
Common stock issued | $ 577 | $ 567 | $ 497 |  |  |
Share Repurchase Plan |  |  |  |  |  |
Shareholders' Equity [Line Items] |  |  |  |  |  |
Stock repurchase program, decrease in equity amount | $ 78,700 |  |  |  |  |
Share Repurchase Plan | Common Stock |  |  |  |  |  |
Shareholders' Equity [Line Items] |  |  |  |  |  |
Number of shares repurchased (in shares) | 4,900,000 |  |  |  |  |
Maximum | Share Repurchase Plan | Warrant |  |  |  |  |  |
Shareholders' Equity [Line Items] |  |  |  |  |  |
Number of shares available for repurchase (in shares) |  |  |  |  | 7,000,000.0 |
Maximum | Share Repurchase Plan | Warrant | Subsequent Event |  |  |  |  |  |
Shareholders' Equity [Line Items] |  |  |  |  |  |
Number of shares available for repurchase (in shares) |  |  |  | 100,000,000 |  |
Dividend Reinvestment and Stock Purchase Plan |  |  |  |  |  |
Shareholders' Equity [Line Items] |  |  |  |  |  |
Authorized and unissued common shares reserved for issuance (in shares) | 3,300,000 |  |  |  |  | 3,300,000
Employee Stock Purchase Plan |  |  |  |  |  |
Shareholders' Equity [Line Items] |  |  |  |  |  |
Number of shares available for purchase (shares) | 500,000 |  |  |  |  |
Shares issued related to dividend reinvestment and stock purchase plan (in shares) | 43,000 | 36,000 |  |  |  |
Common stock issued | $ 577 | $ 567 |  |  |  |

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