Goodwill, Service Contracts and Other Assets (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Nov. 30, 2013	Nov. 30, 2012	Nov. 30, 2013	Nov. 30, 2012
Goodwill, Service Contracts and Other Assets [Abstract]
Gain on sale of equity method investment		$ 8,500,000
Amortization expense	5,900,000	5,900,000	11,741,000	11,973,000
Estimated amortization expense, year one	22,800,000		22,800,000
Estimated amortization expense, year two	20,000,000		20,000,000
Estimated amortization expense, year three	14,800,000		14,800,000
Estimated amortization expense, year four	9,600,000		9,600,000
Estimated amortization expense, year five	8,400,000		8,400,000
Cost method investments, losses due to impairment	$ 0	$ 0	$ 0	$ 0