Note 17 - Sales by Product Group (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015
Transfusion [Member]
Net sales by product group:
Net Sales by product group	$ 73,589	$ 79,929	$ 235,296	$ 247,950
Transplant & Molecular [Member]
Net sales by product group:
Net Sales by product group	15,304	15,676	46,558	46,373
Net Sales by product group	$ 88,893	$ 95,605	$ 281,854	$ 294,323