Goodwill (Key Ratios Used to Measure Goodwill of Property and Casualty Insurance Reporting Unit for Impairment) (Detail) (Property And Casualty Insurance Reporting Unit [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	May 31, 2012 Ratios
Goodwill [Line Items]
Goodwill	$ 17,177	$ 17,177
Number of key ratios used		2
Fair value of the property and casualty insurance reporting unit exceeding carrying value		205.60%
Annual [Member]
Goodwill [Line Items]
Average price to book		1.17
Median price to earnings		12.1