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Subsequent Event - Additional Information (Detail) - $ / shares
3 Months Ended
Apr. 30, 2019
Mar. 31, 2019
Mar. 31, 2018
Subsequent Event [Line Items]      
Dividends on common stock, per share   $ 0.07 $ 0.07
Dividend declared date   Apr. 30, 2019  
Dividend record date   May 17, 2019  
Dividend payable date   May 31, 2019  
Subsequent Event [Member]      
Subsequent Event [Line Items]      
Dividends on common stock, per share $ 0.07