Quarterly report pursuant to Section 13 or 15(d)

Assumptions Used in Black-Scholes Option-Pricing Model (Detail)

v2.4.0.6
Assumptions Used in Black-Scholes Option-Pricing Model (Detail)
3 Months Ended 6 Months Ended
Dec. 31, 2011
Year
Dec. 31, 2010
Year
Dec. 31, 2011
Year
Dec. 31, 2010
Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Dividend yield 1.60% 1.80% 1.50% 1.80%
Expected annualized volatility 22.00% 27.00%    
Expected annualized volatility, minimum     22.00% 22.00%
Expected annualized volatility, maximum     23.00% 27.00%
Risk free interest rate 1.90% 2.00%    
Risk free interest rate, minimum     1.40% 1.30%
Risk free interest rate, maximum     1.90% 2.00%
Expected life 7 7 6 7