Goodwill, Service Contracts and Other Assets - Information Regarding Service Contracts and Other Assets (Details) - USD ($) $ in Thousands	Nov. 30, 2016	May 31, 2016
Information regarding service contracts and other assets
Service contracts, net	$ 85,517	$ 83,715
Other assets, carrying amount	63,322	57,653
Other assets, accumulated amortization	44,057	43,370
Other assets, net	19,265	14,283
Noncompete and consulting agreements
Information regarding service contracts and other assets
Other assets, carrying amount	43,056	42,378
Other assets, accumulated amortization	41,132	40,928
Other assets, net	1,924	1,450
Other
Information regarding service contracts and other assets
Other assets, carrying amount	20,266	15,275
Other assets, accumulated amortization	2,925	2,442
Other assets, net	17,341	12,833
Service Contracts
Information regarding service contracts and other assets
Service contracts, carrying amount	403,234	395,482
Service contracts, accumulated amortization	317,717	311,767
Service contracts, net	$ 85,517	$ 83,715