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Share Repurchase Plan (Details) - USD ($) | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Sep. 16, 2019 | Mar. 19, 2018
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |
Repurchased common shares (in shares) | 411,430 | 470,708 | 321,731 |  |
Cost to repurchase common shares | $ 12,559,000 | $ 18,222,000 | $ 12,256,000 |  |
March 19, 2018 Plan |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |
Stock repurchase program, authorized amount |  |  |  |  | $ 50,000,000
Repurchased common shares (in shares) | 792,439 | 470,708 | 321,731 |  |
Cost to repurchase common shares | $ 30,500,000 | $ 18,200,000 | $ 12,300,000 |  |
Cost to repurchase common shares (in dollars per share) | $ 38.46 | $ 38.71 | $ 38.10 |  |
September 16, 2019 Plan |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |
Stock repurchase program, authorized amount |  |  |  | $ 50,000,000 |
Repurchased common shares (in shares) | 411,430 | 0 |  |  |
Cost to repurchase common shares | $ 12,600,000 |  |  |  |
Cost to repurchase common shares (in dollars per share) | $ 30.52 |  |  |  |

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