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Stock Option Plans and Restricted Stock Awards - Estimated Fair Value of Stock Options (Detail) - Stock Options [Member] - $ / shares
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Dividend yield 2.50% 2.60% 2.90%
Volatility 47.70% 50.30% 50.50%
Risk-free interest rate 1.50% 1.50% 1.20%
Expected life 6 years 1 month 6 days 6 years 3 months 18 days 6 years 7 months 6 days
Weighted average grant date fair value $ 5.83 $ 5.70 $ 4.68