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Recent Developments - Additional Information (Details) - USD ($) |  |  |  | 9 Months Ended
--- | --- | --- | --- | ---
Oct. 19, 2017 | Jul. 31, 2017 | Jul. 27, 2017 | Sep. 30, 2017
Recent Developments [Line Items] |  |  |  |
Stock issued through public offering |  |  |  | $ 60,217,000
Gross proceeds from initial public offering |  |  | $ 65,700,000 |
Net proceeds from initial public offering |  |  | 25,000,000 |
Subsequent Event |  |  |  |
Recent Developments [Line Items] |  |  |  |
Cash dividends declared per share | $ 0.08 |  |  |
Cash dividend payable date | Nov. 30, 2017 |  |  |
Cash dividend declared, record date | Oct. 31, 2017 |  |  |
Nasdaq Global Select Market |  |  |  |
Recent Developments [Line Items] |  |  |  |
Increase in capital net of expenses |  |  | $ 60,200,000 |
Common Stock |  |  |  |
Recent Developments [Line Items] |  |  |  |
Stock issued through public offering, shares |  |  |  | 2,857,756
Stock issued through public offering |  |  |  | $ 60,217,000
Number of shares sold |  |  | 2,857,756 |
Stock sold by selling shareholders |  |  | 892,244 |
Initial Public Offering |  |  |  |
Recent Developments [Line Items] |  |  |  |
Stock issued through public offering, shares |  | 3,750,000 | 3,750,000 | 3,000,000
Share price per share |  | $ 23.00 | $ 23.00 |
Stock issued through public offering |  |  | $ 86,250,000 |

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