Goodwill, Service Contracts and Other Assets - Information Regarding Service Contracts and Other Assets (Details) - USD ($) $ in Thousands	Nov. 30, 2017	May 31, 2017
Information regarding service contracts and other assets
Service contracts, net	$ 565,574	$ 586,988
Other assets, carrying amount	76,624	75,633
Other assets, accumulated amortization	47,464	43,666
Other assets, net	29,160	31,967
Noncompete and consulting agreements
Information regarding service contracts and other assets
Other assets, carrying amount	40,913	40,743
Other assets, accumulated amortization	39,588	39,244
Other assets, net	1,325	1,499
Other
Information regarding service contracts and other assets
Other assets, carrying amount	35,711	34,890
Other assets, accumulated amortization	7,876	4,422
Other assets, net	27,835	30,468
Service Contracts
Information regarding service contracts and other assets
Service contracts, carrying amount	917,072	911,273
Service contracts, accumulated amortization	351,498	324,285
Service contracts, net	$ 565,574	$ 586,988