Goodwill (Key Ratios to Measure Goodwill of Bank Reporting Unit for Impairment) (Detail) (Bank Reporting Unit [Member])	12 Months Ended
	May 31, 2014	May 31, 2014 Annual [Member]	May 31, 2013 Annual [Member]
Goodwill [Line Items]
Price to book		1.48	1.57
Price to tangible book		1.70	1.80
Price to earnings		20.5	22.1
Previous annual time period	12 months