Goodwill, Service Contracts and Other Assets Narrative (Details) (USD $)	3 Months Ended	6 Months Ended
	Nov. 30, 2012	Nov. 30, 2012	Nov. 30, 2011	May 31, 2012
Goodwill, Service Contracts and Other Assets [Abstract]
Cash surrender value of insurance policies	$ 67,000,000	$ 67,000,000		$ 57,400,000
Equity method investments	27,200,000	27,200,000		31,900,000
Cost method investments	900,000	900,000		900,000
Gain (Loss) on Sale of Equity Investments	8,500,000
Amortization expense		11,973,000	20,104,000
Estimated amortization expense, year one		23,100,000
Estimated amortization expense, year two		20,700,000
Estimated amortization expense, year three		17,800,000
Estimated amortization expense, year four		12,600,000
Estimated amortization expense, year five		$ 7,600,000