Goodwill, Service Contracts and Other Assets Narrative (Details) (USD $)	3 Months Ended			9 Months Ended
	Feb. 28, 2013	Nov. 30, 2012	Feb. 29, 2012	Feb. 28, 2013	Feb. 29, 2012	May 31, 2012
Goodwill, Service Contracts and Other Assets [Abstract]
Cash surrender value of insurance policies	$ 70,500,000			$ 70,500,000		$ 57,400,000
Equity method investments	27,700,000			27,700,000		31,900,000
Cost method investments	900,000			900,000		900,000
Gain (Loss) on Sale of Equity Investments		8,500,000
Amortization expense				17,884,000	29,520,000
Estimated amortization expense, year one	23,500,000			23,500,000
Estimated amortization expense, year two	21,600,000			21,600,000
Estimated amortization expense, year three	18,700,000			18,700,000
Estimated amortization expense, year four	13,600,000			13,600,000
Estimated amortization expense, year five	8,500,000			8,500,000
Cost method investments, losses due to impairment	$ 0		$ 0	$ 0	$ 0