Goodwill, Service Contracts and Other Assets (Narrative) (Details) (USD $)	12 Months Ended
	May 31, 2014	May 31, 2013	May 31, 2012
Goodwill, Service Contracts and Other Assets [Abstract]
Amortization of intangible assets	$ 22,642,000	$ 23,713,000	$ 38,334,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Estimated amortization expense, year one	15,700,000
Estimated amortization expense, year two	11,300,000
Estimated amortization expense, year three	6,700,000
Estimated amortization expense, year four	5,700,000
Estimated amortization expense, year five	$ 5,400,000