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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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