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Related Party Transactions - Additional Information (Detail) - $ / shares
Aug. 16, 2017
May 09, 2017
Jan. 03, 2017
Officer [Member]      
Related Party Transaction [Line Items]      
Purchase of shares   2,500 1,834
Shares price per share   $ 52.05 $ 58.58
Number of trading days to be considered for average price of stock repurchased   30 days 30 days
Trust [Member]      
Related Party Transaction [Line Items]      
Purchase of shares 24,920    
Shares price per share $ 50.16    
Number of trading days to be considered for average price of stock repurchased 30 days