Goodwill, Service Contracts and Other Assets (Details 3) (USD $) In Thousands, unless otherwise specified	May 31, 2012		May 31, 2011		May 31, 2010
Information regarding service contracts and other assets
Service contracts, Net	$ 76,822		$ 102,312		$ 103,445
Other Assets, Carrying Amount	186,062		183,423
Other Assets, Accumulated Amortization	73,226		68,672
Other Assets, Net	112,836		114,751
Noncompete agreements [Member]
Information regarding service contracts and other assets
Other Assets, Carrying Amount	76,036		76,091
Other Assets, Accumulated Amortization	69,954		63,982
Other Assets, Net	6,082		12,109
Investments [Member]
Information regarding service contracts and other assets
Other Assets, Carrying Amount	90,198	[1]	84,197	[1]
Other Assets, Accumulated Amortization	0	[1]	0	[1]
Other Assets, Net	90,198	[1]	84,197	[1]
Other [Member]
Information regarding service contracts and other assets
Other Assets, Carrying Amount	19,828		23,135
Other Assets, Accumulated Amortization	3,272		4,690
Other Assets, Net	16,556		18,445
Service Contracts [Member]
Information regarding service contracts and other assets
Service contracts, Carrying Amount	384,622		379,967
Service contracts, Accumulated Amortization	307,800		277,655
Service contracts, Net	$ 76,822		$ 102,312

[1] Investments at May 31, 2012, include the cash surrender value of insurance policies of $57.4 million, equity method investments of $31.9 million and cost method investments of $0.9 million. Investments at May 31, 2011, include the cash surrender value of insurance policies of $51.1 million, equity method investments of $30.2 million and cost method investments of $2.9 million.