Note 16 - Sales by Product Group (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2015	Nov. 30, 2014
Transfusion [Member]
Net sales by product group:
Net Sales by product group	$ 80,521	$ 81,652	$ 161,710	$ 168,020
Transplant & Molecular [Member]
Net sales by product group:
Net Sales by product group	15,728	14,625	31,251	30,697
Net Sales by product group	$ 96,249	$ 96,277	$ 192,961	$ 198,717