Accrued Liabilities (Details) - USD ($) $ in Thousands	May. 31, 2015	May. 31, 2014
Accrued liabilities
Payroll and related expenses	$ 10,330	$ 8,114
Royalties	2,237	2,620
Accrued severance	158	765
Sales and franchise taxes	808	154
Interest rate swap liability	489	1,327
Accrued Professional Fees	1,522	983
Outside services	257	555
Other	2,530	2,733
Total	$ 18,331	$ 17,251