Goodwill, Service Contracts and Other Assets (Narrative) (Details) (USD $)	12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011
Goodwill, Service Contracts and Other Assets [Abstract]
Amortization of intangible assets	$ 23,713,000	$ 38,334,000	$ 42,581,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Estimated amortization expense, year one	22,100,000
Estimated amortization expense, year two	19,200,000
Estimated amortization expense, year three	14,000,000
Estimated amortization expense, year four	8,900,000
Estimated amortization expense, year five	$ 7,700,000