Goodwill, Service Contracts and Other Assets (Narrative) (Details) (USD $)	3 Months Ended			9 Months Ended
	Feb. 28, 2014	Feb. 28, 2013	Nov. 30, 2012	Feb. 28, 2014	Feb. 28, 2013
Goodwill, Service Contracts and Other Assets [Abstract]
Gain on sale of equity method investment			$ 8,500,000
Amortization expense	5,800,000	5,900,000		17,524,000	17,884,000
Estimated amortization expense, year one	22,900,000			22,900,000
Estimated amortization expense, year two	20,100,000			20,100,000
Estimated amortization expense, year three	14,900,000			14,900,000
Estimated amortization expense, year four	9,700,000			9,700,000
Estimated amortization expense, year five	8,500,000			8,500,000
Cost method investments, losses due to impairment	$ 0	$ 0		$ 0	$ 0