Stock-Based Compensation - Weighted Average Assumptions Used to Estimate Fair Values (Detail) (Stock Incentive Plan 1990 [Member], Class B Common Stock)	6 Months Ended
	Nov. 30, 2013	Nov. 30, 2012
Stock Incentive Plan 1990 [Member] | Class B Common Stock
Common Stock and Share Based Compensation [Line Items]
Dividend yield	1.30%	1.50%
Expected volatility	27.90%	35.00%
Weighted average expected life (in years)	5 years 3 months 18 days	5 years 3 months 18 days
Risk-free interest rate	1.30%	0.60%