Minimum annual rental commitments under noncancellable leases (Details) (USD $) In Thousands, unless otherwise specified	May 31, 2014
Minimum annual rental commitments under noncancellable leases
Future minimum lease commitments in 2015	$ 133
Future minimum lease commitments in 2016	133
Future minimum lease commitments in 2017	110
Total future minimum lease commitments	$ 376