Computation Of Basic And Diluted Earnings per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2011	May 31, 2011	Feb. 28, 2011	Nov. 30, 2010	Aug. 31, 2010	May 31, 2012	May 31, 2011	May 31, 2010
Numerator (basic & diluted):
Net earnings (loss) attributable to controlling interest - income (loss) available to common shareholders									$ 115,595	$ 115,066	$ 45,241
Denominator:
Denominator for basic earnings (loss) per share attributable to controlling interest - weighted average common shares									69,651	74,803	79,127
Effect of dilutive securities									601	606	16
Denominator for diluted earnings (loss) per share attributable to controlling interest - adjusted weighted average common shares									70,252	75,409	79,143
Basic earnings (loss) per share attributable to controlling interest	$ 0.76	$ 0.38	$ 0.17	$ 0.36	$ 0.71	$ 0.35	$ 0.20	$ 0.29	$ 1.66	$ 1.54	$ 0.57
Diluted earnings (loss) per share attributable to controlling interest	$ 0.75	$ 0.37	$ 0.17	$ 0.35	$ 0.70	$ 0.35	$ 0.20	$ 0.29	$ 1.65	$ 1.53	$ 0.57