Quarterly report pursuant to Section 13 or 15(d)

Fair Value of Employee Stock Options Granted as Determined by Black-Scholes Valuation Model Assumptions (Detail)

v3.4.0.3
Fair Value of Employee Stock Options Granted as Determined by Black-Scholes Valuation Model Assumptions (Detail) - Nonqualified Stock Options [Member]
3 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Stockholders Equity Note [Line Items]    
Expected life (in years) 7 years 6 months 7 years 6 months
Risk-free interest rate 1.66% 2.07%
Expected volatility 23.60% 20.61%
Expected dividend yield 2.94% 2.63%