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)

v3.7.0.1
Fair Value of Employee Stock Options Granted as Determined by Black-Scholes Valuation Model Assumptions (Detail) - $ / shares
3 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Nonqualified Stock Options [Member]    
Stockholders Equity Note [Line Items]    
Risk-free interest rate 2.15% 1.66%
Expected volatility 17.81% 23.60%
Weighted-average fair value of options granted (usd per share) $ 14.70 $ 17.32
Expected dividend yield 2.89% 2.94%
Expected life (in years) 7 years 6 months 7 years 6 months
Long-Term Incentive Performance Award    
Stockholders Equity Note [Line Items]    
Risk-free interest rate 1.46% 1.01%
Expected volatility 16.59% 16.45%
Weighted-average fair value of options granted (usd per share) $ 119.29 $ 135.57
Expected dividend yield 113.55% 128.59%