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Other - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 6 Months Ended
Jul. 31, 2018
May 15, 2018
Feb. 15, 2018
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Other [Line Items]              
Dividend paid           $ 1,535 $ 1,235
Quarterly dividend declared       $ 0.0425 $ 0.0425 $ 0.0850 $ 0.0850
Dividend Paid              
Other [Line Items]              
Dividend paid   $ 900 $ 600        
Dividend declared, date of record   May 01, 2018 Feb. 01, 2018        
Dividend payable       $ 900   $ 900  
Dividend payable date           Aug. 15, 2018  
Dividend Declared | Subsequent Event              
Other [Line Items]              
Dividend declared, date of record Nov. 01, 2018            
Dividend payable date Nov. 15, 2018            
Quarterly dividend declared $ 0.0425