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Stock-based Compensation - Restricted , Performance and Deferred Stock Units (Details) - USD ($) $ / shares in Units, $ in Thousands |  |  |  | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | ---
Sep. 22, 2021 | May 19, 2021 | Mar. 24, 2021 | Sep. 30, 2021 | Mar. 31, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Dec. 31, 2020
Additional disclosures |  |  |  |  |  |  |  |  |
Compensation expense recognized |  |  |  | $ 1,837 |  | $ 2,205 | $ 5,722 | $ 4,413 |
Period over which cost will be recognized |  |  |  |  |  |  | 3 years |  | 3 years
RSUs |  |  |  |  |  |  |  |  |
Shares |  |  |  |  |  |  |  |  |
Non-vested at beginning of period (in shares) |  |  |  |  | 1,017,038 |  | 1,017,038 |  |
Granted (in shares) |  |  |  |  |  |  | 260,231 |  |
Dividend equivalents earned (in shares) |  |  |  |  |  |  | 33,388 |  |
Vested (in shares) |  |  |  |  |  |  | (128,824) |  |
Forfeited (in shares) |  |  |  |  |  |  | (29,883) |  |
Non-vested at end of period (in shares) |  |  |  | 1,151,950 |  |  | 1,151,950 |  | 1,017,038
Weighted-Average Grant Date Fair Value |  |  |  |  |  |  |  |  |
Non-vested at beginning of period (in dollars per share) |  |  |  |  | $ 23.87 |  | $ 23.87 |  |
Granted (in dollars per share) |  |  |  |  |  |  | 24.26 |  |
Dividend equivalents earned (in dollars per share) |  |  |  |  |  |  | 23.07 |  |
Vested (in dollars per share) |  |  |  |  |  |  | 22.88 |  |
Forfeited (in dollars per share) |  |  |  |  |  |  | 24.88 |  |
Non-vested at end of period (in dollars per share) |  |  |  | $ 24.02 |  |  | $ 24.02 |  | $ 23.87
Additional disclosures |  |  |  |  |  |  |  |  |
Compensation expense recognized |  |  |  | $ 1,316 |  | 2,029 | $ 4,362 | 3,952 |
DSUs |  |  |  |  |  |  |  |  |
Shares |  |  |  |  |  |  |  |  |
Non-vested at beginning of period (in shares) |  |  |  |  | 34,263 |  | 34,263 |  |
Granted (in shares) |  |  |  |  |  |  | 35,664 |  |
Dividend equivalents earned (in shares) |  |  |  |  |  |  | 3,716 |  |
Vested (in shares) |  |  |  |  |  |  | (39,813) |  |
Non-vested at end of period (in shares) |  |  |  | 33,830 |  |  | 33,830 |  | 34,263
Vested and Outstanding at end of period (in shares) |  |  |  | 96,427 |  |  | 96,427 |  |
Weighted-Average Grant Date Fair Value |  |  |  |  |  |  |  |  |
Non-vested at beginning of period (in dollars per share) |  |  |  |  | $ 17.18 |  | $ 17.18 |  |
Granted (in dollars per share) |  |  |  |  |  |  | 24.59 |  |
Dividend equivalents earned (in dollars per share) |  |  |  |  |  |  | 23.15 |  |
Vested (in dollars per share) |  |  |  |  |  |  | 18.08 |  |
Non-vested at end of period (in dollars per share) |  |  |  | $ 24.59 |  |  | 24.59 |  | $ 17.18
Vested and Outstanding at end of period (in dollars per share) |  |  |  | $ 21.99 |  |  | $ 21.99 |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Compensation expense recognized |  |  |  | $ 231 |  | 135 | $ 741 | 420 |
PSUs |  |  |  |  |  |  |  |  |
Shares |  |  |  |  |  |  |  |  |
Non-vested at beginning of period (in shares) |  |  |  |  | 15,724 |  | 15,724 |  |
Granted (in shares) |  |  |  |  | 28,344 |  | 99,159 |  |
Forfeited (in shares) |  |  |  |  |  |  | (968) |  |
Non-vested at end of period (in shares) |  |  |  | 113,915 |  |  | 113,915 |  | 15,724
Weighted-Average Grant Date Fair Value |  |  |  |  |  |  |  |  |
Non-vested at beginning of period (in dollars per share) |  |  |  |  | $ 16.25 |  | $ 16.25 |  |
Granted (in dollars per share) |  |  |  |  |  |  | 23.91 |  |
Forfeited (in dollars per share) |  |  |  |  |  |  | 23.48 |  |
Non-vested at end of period (in dollars per share) |  |  |  | $ 22.86 |  |  | $ 22.86 |  | $ 16.25
Additional disclosures |  |  |  |  |  |  |  |  |
Grant date fair value of the award |  |  |  |  | $ 700 |  |  |  |
Compensation expense recognized |  |  |  | $ 290 |  | $ 41 | $ 619 | $ 41 |
PSUs | Minimum |  |  |  |  |  |  |  |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Vesting percentage (as a percent) |  |  |  |  | 0.00% |  |  |  |
PSUs | Maximum |  |  |  |  |  |  |  |  |
Shares |  |  |  |  |  |  |  |  |
Granted (in shares) |  |  |  |  | 39,682 |  |  |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Vesting percentage (as a percent) |  |  |  |  | 140.00% |  |  |  |
Market Based Performance Stock Units |  |  |  |  |  |  |  |  |
Shares |  |  |  |  |  |  |  |  |
Granted (in shares) |  |  |  |  | 70,815 |  |  |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Grant date fair value of the award |  |  |  |  | $ 1,700 |  |  |  |
Market Based Performance Stock Units | Minimum |  |  |  |  |  |  |  |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Vesting percentage (as a percent) |  |  |  |  | 0.00% |  |  |  |
Market Based Performance Stock Units | Maximum |  |  |  |  |  |  |  |  |
Shares |  |  |  |  |  |  |  |  |
Granted (in shares) |  |  |  |  | 113,304 |  |  |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Vesting percentage (as a percent) |  |  |  |  | 160.00% |  |  |  |
2020 Equity Incentive Plan |  |  |  |  |  |  |  |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Remaining shares available for issuance |  |  |  | 1,038,975 |  |  | 1,038,975 |  |
2020 Equity Incentive Plan | Members of management |  |  |  |  |  |  |  |  |
Shares |  |  |  |  |  |  |  |  |
Granted (in shares) | 47,805 |  |  |  |  |  |  |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Grant date fair value of the award | $ 1,100 |  |  |  |  |  |  |  |
Vesting percentage (as a percent) | 100.00% |  |  |  |  |  |  |  |
2020 Equity Incentive Plan | Members of management | Minimum |  |  |  |  |  |  |  |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Period over which cost will be recognized | 3 years |  |  |  |  |  |  |  |
2020 Equity Incentive Plan | Members of management | Maximum |  |  |  |  |  |  |  |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Period over which cost will be recognized | 5 years |  |  |  |  |  |  |  |
2020 Equity Incentive Plan | RSUs | Members of management, including the Vice-Chairman of the Board |  |  |  |  |  |  |  |  |
Shares |  |  |  |  |  |  |  |  |
Granted (in shares) |  |  | 212,426 |  |  |  |  |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Grant date fair value of the award |  |  | $ 5,200 |  |  |  |  |  |
Accelerated vesting provision, minimum requisite service period |  |  | 1 year |  |  |  |  |  |
Vesting percentage (as a percent) |  |  | 100.00% |  |  |  |  |  |
2020 Equity Incentive Plan | RSUs | Members of management, including the Vice-Chairman of the Board | Minimum |  |  |  |  |  |  |  |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Period over which cost will be recognized |  |  | 1 year |  |  |  |  |  |
2020 Equity Incentive Plan | RSUs | Members of management, including the Vice-Chairman of the Board | Maximum |  |  |  |  |  |  |  |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Period over which cost will be recognized |  |  | 5 years |  |  |  |  |  |
2020 Equity Incentive Plan | DSUs | Directors and Advisory Directors |  |  |  |  |  |  |  |  |
Shares |  |  |  |  |  |  |  |  |
Granted (in shares) |  |  | 33,288 |  |  |  |  |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Grant date fair value of the award |  |  | $ 800 |  |  |  |  |  |
Period over which cost will be recognized |  |  | 1 year |  |  |  |  |  |
Vesting percentage (as a percent) |  |  | 100.00% |  |  |  |  |  |
2020 Equity Incentive Plan | DSUs | Directors |  |  |  |  |  |  |  |  |
Shares |  |  |  |  |  |  |  |  |
Granted (in shares) |  | 2,376 |  |  |  |  |  |  |
Additional disclosures |  |  |  |  |  |  |  |  |
Grant date fair value of the award |  | $ 100 |  |  |  |  |  |  |
Period over which cost will be recognized |  | 1 year |  |  |  |  |  |  |
Vesting percentage (as a percent) |  | 100.00% |  |  |  |  |  |  |

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