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Equity Transactions - Additional Information (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Stockholders Equity [Line Items]      
Preferred stock authorized but unissued and undesignated 10,000,000 10,000,000  
Expiration date on repurchase authorizations Sep. 30, 2016    
Aggregate cost shares of common stock $ 11,279,000 $ 1,676,000 $ 8,323,000
Common stock acquired, shares 288,000    
Maximum [Member]      
Stockholders Equity [Line Items]      
Authorization amount for repurchase of common stock $ 75,000,000    
Common Stock [Member]      
Stockholders Equity [Line Items]      
Common stock acquired, shares 3,076,000    
Since Approval of Share Repurchase Plan [Member]      
Stockholders Equity [Line Items]      
Aggregate cost shares of common stock $ 60,414,000    
Remaining authorized repurchase amount $ 14,586,000