Processing System Intrusion (Details) (USD $)	3 Months Ended		9 Months Ended		24 Months Ended
	Feb. 28, 2014	Feb. 28, 2013	Feb. 28, 2014	Feb. 28, 2013	Feb. 28, 2014
Extraordinary and Unusual Items [Abstract]
Insurance proceeds		$ 18,000,000	$ 7,000,000		$ 27,000,000
Processing system intrusion expense (credit)	$ 0	$ (1,189,000)	$ (7,000,000)	$ 8,311,000