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Stock Incentive Plans - Summary of Fair Value of Stock Option Awards (Detail) (USD $)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]    
Expected volatility 65.90% 65.90%
Risk free interest rate 2.90% 2.90%
Expected dividend yield 2.50% 2.30%
Expected term 7 years 3 months 18 days 7 years 3 months 18 days
Weighted average fair value per share $ 9.08 $ 7.20