Common Shares and Stock-Based Compensation - Estimated Fair Value of Different Class of Stocks under Assumptions of Black-Scholes Option-Pricing Model (Detail)	12 Months Ended
	Feb. 28, 2013 Y	Feb. 29, 2012 Y	Feb. 28, 2011 Y
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate			1.40%
Dividend yield			2.30%
Expected stock volatility			0.81%
Expected life in years			2 years 3 months 18 days
Risk-free interest rate	0.38%		1.62%
Dividend yield	4.20%		4.38%
Expected stock volatility	0.43%		0.76%
Expected life in years	2.8		2.5
Risk-free interest rate	0.29%	0.67%	1.09%
Dividend yield	3.79%	2.60%	2.30%
Expected stock volatility	0.42%	0.59%	0.90%
Expected life in years	1.6	1.6	1.6