Goodwill, Service Contracts and Other Assets (Information Regarding Service Contracts and Other Assets) (Details) (USD $)	Aug. 31, 2013		May 31, 2013
Information regarding service contracts and other assets
Service contracts, Net	$ 93,119,000		$ 92,153,000
Other Assets, Carrying Amount	202,159,000		202,099,000
Other Assets, Accumulated Amortization	78,727,000		77,709,000
Other Assets, Net	123,432,000		124,390,000
Cash surrender value of insurance policies	72,000,000		73,000,000
Equity method investments	27,700,000		27,600,000
Cost method investments	900,000		900,000
Noncompete and consulting agreements [Member]
Information regarding service contracts and other assets
Other Assets, Carrying Amount	78,833,000		77,863,000
Other Assets, Accumulated Amortization	73,608,000		72,970,000
Other Assets, Net	5,225,000		4,893,000
Investments [Member]
Information regarding service contracts and other assets
Other Assets, Carrying Amount	100,648,000	[1]	101,525,000	[1]
Other Assets, Accumulated Amortization	0	[1]	0	[1]
Other Assets, Net	100,648,000	[1]	101,525,000	[1]
Other [Member]
Information regarding service contracts and other assets
Other Assets, Carrying Amount	22,678,000		22,711,000
Other Assets, Accumulated Amortization	5,119,000		4,739,000
Other Assets, Net	17,559,000		17,972,000
Service Contracts [Member]
Information regarding service contracts and other assets
Service contracts, Carrying Amount	426,391,000		420,499,000
Service contracts, Accumulated Amortization	333,272,000		328,346,000
Service contracts, Net	$ 93,119,000		$ 92,153,000

[1] Investments at August 31, 2013, include the cash surrender value of insurance policies of $72.0 million, equity method investments of $27.7 million and cost method investments of $0.9 million. Investments at May 31, 2013, include the cash surrender value of insurance policies of $73.0 million, equity method investments of $27.6 million and cost method investments of $0.9 million.