Note 2 - Business Combinations (Details) (USD $)	3 Months Ended		9 Months Ended				9 Months Ended		12 Months Ended	3 Months Ended			9 Months Ended	12 Months Ended	21 Months Ended
	Feb. 28, 2014	Feb. 28, 2013	Feb. 28, 2014	Feb. 28, 2013	May 31, 2013	May 31, 2012	Feb. 28, 2014 UNITED KINGDOM LIFECODES [Member]	Feb. 28, 2014 ITALY LIFECODES [Member]	May 31, 2013 Contingent Consideration [Member] LIFECODES [Member]	Feb. 28, 2014 LIFECODES [Member]	Nov. 30, 2013 LIFECODES [Member]	Aug. 31, 2013 LIFECODES [Member]	Feb. 28, 2014 LIFECODES [Member]	May 31, 2013 LIFECODES [Member]	Feb. 28, 2014 LIFECODES [Member]	Mar. 22, 2013 LIFECODES [Member]
Note 2 - Business Combinations (Details) [Line Items]
Business Combination, Consideration Transferred							$ 4,000,000	$ 2,400,000							$ 86,200,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents							1,200,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill										3,500,000			3,500,000		3,500,000
Goodwill	1,005,778,000		1,005,778,000		1,003,463,000	966,338,000				1,100,000			1,100,000		1,100,000
Payments to Acquire Businesses, Gross														87,300,000
Proceeds from Previous Acquisition												(1,100,000)
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High																10,000,000
Business Combination, Contingent Consideration, Liability					4,504,000					0			0	4,500,000	0	4,400,000
Accretion Expense									100,000
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability											(3,300,000)	(1,300,000)	(4,500,000)
Business Combination, Bargain Purchase, Gain Recognized, Amount													4,600,000
Revenue, Net	90,979,000	86,192,000	287,226,000	253,402,000						11,000,000			35,300,000
Income (Loss) from Continuing Operations before Income Taxes, Domestic										$ 0			$ 1,300,000