Note 14 - Option Activity (Details) - USD ($)		3 Months Ended		6 Months Ended
		Nov. 30, 2015	Aug. 31, 2015	Nov. 30, 2015
Employee Stock Option [Member]
Service-based options outstanding at May 31, 2015 (in shares)			158,329	158,329
Service-based options outstanding at May 31, 2015 (in dollars per share)			$ 100	$ 100
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		248,825	279,247	528,072
Granted (in dollars per share)				$ 100
Exercised (in shares)				0
Exercised (in dollars per share)				$ 0
Forfeited (in shares)				(16,386)
Forfeited (in dollars per share)				$ 100
Expired or cancelled (in shares)				(730)
Expired or cancelled (in dollars per share)				$ 100
Service-based options outstanding at November 30, 2015 (in shares)		669,285		669,285
Service-based options outstanding at November 30, 2015 (in dollars per share)		$ 100		$ 100
Service-based options outstanding at November 30, 2015				8 years 109 days
Service-based options outstanding at November 30, 2015	[1]	$ 0		$ 0
Exercisable at November 30, 2015 (in shares)		142,163		142,163
Exercisable at November 30, 2015 (in dollars per share)		$ 100		$ 100
Exercisable at November 30, 2015				6 years 182 days
Exercisable at November 30, 2015	[1]	$ 0		$ 0
Forfeited (in shares)				16,386
Performance Shares [Member]
Service-based options outstanding at May 31, 2015 (in shares)			149,329	149,329
Service-based options outstanding at May 31, 2015 (in dollars per share)			$ 100	$ 100
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		6,538		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)				(101,027)
Expired or cancelled (in dollars per share)				$ 100
Service-based options outstanding at November 30, 2015 (in shares)		34,657		34,657
Service-based options outstanding at November 30, 2015 (in dollars per share)		$ 100		$ 100
Service-based options outstanding at November 30, 2015				6 years 36 days
Service-based options outstanding at November 30, 2015	[1]	$ 0		$ 0
Exercisable at November 30, 2015 (in shares)		34,657		34,657
Exercisable at November 30, 2015 (in dollars per share)		$ 100		$ 100
Exercisable at November 30, 2015				6 years 36 days
Exercisable at November 30, 2015	[1]	$ 0		$ 0
Forfeited (in shares)				(20,183)

[1] The aggregate intrinsic value in the above table represents the total pre-tax amount that a participant would receive if the option had been exercised on the last day of the respective fiscal year. Options with a market value less than its exercise value are not included in the intrinsic value amount.