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Stockholders' Equity - Additional Information (Detail) - USD ($)
3 Months Ended 9 Months Ended
Oct. 30, 2017
Jul. 25, 2011
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Sep. 30, 2017
Sep. 30, 2016
Stockholders Equity [Line Items]                    
Common stock, value of shares authorized to repurchase   $ 200,000,000                
Stock repurchase, shares   1,770,000             0 45,000
Value of shares repurchased   $ 52,000,000               $ 1,545,000
Average price of repurchased shares                   $ 34.50
Cash dividends per common share     $ 0.175 $ 0.175 $ 0.175 $ 0.170 $ 0.170 $ 0.170 $ 0.525 $ 0.510
Dividend payment to common shareholders     $ 28,403,000 $ 28,403,000 $ 28,403,000 $ 27,249,000 $ 27,249,000 $ 27,249,000 $ 28,403,000 $ 27,249,000
Subsequent Event [Member]                    
Stockholders Equity [Line Items]                    
Dividend declared date Oct. 30, 2017                  
Cash dividend to be paid $ 0.18                  
Dividend to be paid date Dec. 08, 2017                  
Dividend declared, shareholders of record date Nov. 27, 2017