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Common Stock and Earnings Per Share - Additional Information (Detail) - $ / shares
12 Months Ended
Mar. 11, 2015
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Dilutive Securities Included And Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]        
Antidilutive potentially securities   60,200 40,400 58,800
Initial conversion price per share   $ 68.90    
Additional diluted outstanding shares   0    
4.50% Convertible Senior Notes due 2020 [Member]        
Dilutive Securities Included And Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]        
Debt instrument interest rate 4.50% 4.50%    
Debt Instrument Maturity Year 2020 2020    
Initial conversion price per share   $ 68.90