Fair Value Disclosures (Narrative) (Details) (USD $)	12 Months Ended
	May 31, 2014	May 31, 2013	May 31, 2012	Apr. 30, 2014
Fair Value Disclosures [Abstract]
Amortized cost basis, marketable securities		$ 5,700,000
Marketable securities purchased	48,500,000	167,100,000	579,700,000
Shredding transaction asset impairment charge	16,143,000	0	0
Information systems assets, fair value				$ 5,400,000