Goodwill (Factors Used to Measure Goodwill in Income Approach) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended		3 Months Ended
	May 31, 2012 Annual [Member]	May 31, 2011 Annual [Member]	May 31, 2012 Wealth Management Reporting Unit [Member]	May 31, 2011 Wealth Management Reporting Unit [Member]
Goodwill [Line Items]
Goodwill			$ 82,746	$ 82,746
Future economic benefit period, in years			Ten
Discount rate	17.50%	17.50%
Weighted-average increase in revenues	6.00%	6.00%
Weighted-average increase in expenses	5.00%	5.00%
Fair value of the wealth management reporting unit exceeding carrying value			63.40%	59.70%