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Common Stock and Treasury Stock - Additional Information (Detail) - USD ($)
3 Months Ended 79 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Mar. 31, 2019
Feb. 28, 2018
Equity [Abstract]        
Stock authorized to purchase under stock repurchase program       $ 200,000,000
Repurchase of common stock, shares 23,802 1,346,427 44,153,195  
Repurchase of common stock, value $ 631,000 $ 31,113,000 $ 548,500,000  
Remaining value of shares authorized for purchase under the stock repurchase program $ 176,000,000   $ 176,000,000