Goodwill, Service Contracts and Other Assets - Information Regarding Service Contracts and Other Assets (Details) - USD ($) $ in Thousands	Nov. 30, 2015	May. 31, 2015
Information regarding service contracts and other assets
Service contracts, net	$ 70,183	$ 42,434
Other assets, carrying amount	69,791	65,423
Other assets, accumulated amortization	49,147	47,929
Other assets, net	20,644	17,494
Noncompete and consulting agreements
Information regarding service contracts and other assets
Other assets, carrying amount	42,262	41,828
Other assets, accumulated amortization	40,662	40,379
Other assets, net	1,600	1,449
Other
Information regarding service contracts and other assets
Other assets, carrying amount	27,529	23,595
Other assets, accumulated amortization	8,485	7,550
Other assets, net	19,044	16,045
Service Contracts
Information regarding service contracts and other assets
Service contracts, carrying amount	374,292	340,816
Service contracts, accumulated amortization	304,109	298,382
Service contracts, net	$ 70,183	$ 42,434