Goodwill, Service Contracts and Other Assets - Information Regarding Service Contracts and Other Assets (Details) - USD ($) $ in Thousands	May 31, 2016	May 31, 2015	May 31, 2014
Information regarding service contracts and other assets
Service contracts, net	$ 83,715	$ 42,434	$ 55,675
Other assets, carrying amount	70,321	65,423
Other assets, accumulated amortization	50,460	47,929
Other assets, net	19,861	17,494
Service contracts
Information regarding service contracts and other assets
Service contracts, carrying amount	395,482	340,816
Service contracts, accumulated amortization	311,767	298,382
Service contracts, net	83,715	42,434
Noncompete and consulting agreements
Information regarding service contracts and other assets
Other assets, carrying amount	42,378	41,828
Other assets, accumulated amortization	40,928	40,379
Other assets, net	1,450	1,449
Other
Information regarding service contracts and other assets
Other assets, carrying amount	27,943	23,595
Other assets, accumulated amortization	9,532	7,550
Other assets, net	$ 18,411	$ 16,045