Note 15 - Option Activity (Details) - $ / shares	9 Months Ended
	Feb. 29, 2016	Feb. 29, 2016
Employee Stock Option [Member]
Service-based options outstanding (in shares)	158,329
Service-based options outstanding (in dollars per share)	$ 100
Granted (in shares)	531,072
Granted (in dollars per share)	$ 100
Exercised (in shares)	0
Exercised (in dollars per share)	$ 0
Forfeited (in shares)	(21,186)
Forfeited (in dollars per share)	$ 100
Expired or cancelled (in shares)	(1,910)
Expired or cancelled (in dollars per share)	$ 100
Service-based options outstanding (in shares)	666,305
Service-based options outstanding (in dollars per share)	$ 100
Service-based options outstanding	8 years
Exercisable (in shares)		146,393
Exercisable (in dollars per share)	$ 100	$ 100
Exercisable	6 years 73 days
Performance or market-based options outstanding	8 years
Exercisable (in shares)		146,393
Exercisable	6 years 73 days
Performance Shares [Member]
Service-based options outstanding (in shares)	149,329
Service-based options outstanding (in dollars per share)	$ 100
Granted (in shares)	6,538
Granted (in dollars per share)	$ 100
Exercised (in shares)	0
Exercised (in dollars per share)	$ 0
Forfeited (in shares)	(20,183)
Forfeited (in dollars per share)	$ 100
Expired or cancelled (in shares)	(101,177)
Expired or cancelled (in dollars per share)	$ 100
Service-based options outstanding (in shares)	34,507
Service-based options outstanding (in dollars per share)	$ 100
Service-based options outstanding	5 years 328 days
Exercisable (in shares)		34,507
Exercisable (in dollars per share)	$ 100	$ 100
Exercisable	5 years 328 days
Performance or market-based options outstanding	5 years 328 days
Exercisable (in shares)		34,507
Exercisable (in dollars per share)		$ 100
Exercisable	5 years 328 days