Note 19 - Income Taxes (Details Textual) - USD ($)	3 Months Ended	12 Months Ended			24 Months Ended
	Feb. 28, 2015	May 31, 2016	May 31, 2015	May 31, 2014	May 31, 2016
Holdings [Member]
Taxes Payable		$ 0	$ 0		$ 0
Excluding Discrete Items [Member]
Effective Income Tax Rate Reconciliation, Percent			34.80%
Including Accrued Interest [Member]
Unrecognized Tax Benefits		21,200,000			21,200,000
Discrete Charge [Member]
Income Tax Expense (Benefit)	$ 23,700,000
Non-current Liability [Member]
Unrecognized Tax Benefits		15,200,000	$ 9,100,000		15,200,000
Non-current Deferred Tax Liabilities [Member]
Unrecognized Tax Benefits		6,000,000	4,700,000		6,000,000
Organ-i [Member]
Deferred Tax Liabilities, Intangible Assets		10,200,000			10,200,000
Sentilus [Member]
Deferred Tax Liabilities, Intangible Assets		7,100,000			7,100,000
Sirona Genomics Inc. [Member]
Deferred Tax Liabilities, Intangible Assets		16,500,000			16,500,000
Outside United States[Member]
Deferred Tax Liabilities, Net		7,600,000	10,600,000		7,600,000
BELGIUM
Operating Loss Carryforwards		2,400,000			2,400,000
FRANCE
Operating Loss Carryforwards		300,000			300,000
Domestic Tax Authority [Member]
Operating Loss Carryforwards		46,500,000			46,500,000
Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount		$ 6,900,000			6,900,000
Federal Alternative Minimum Tax Carryovers [Member]
Tax Credit Carryforward, Amount			500,000
Unrecognized Tax Benefits, Income Tax Penalties Expense			$ 0
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Percent		29.10%	(34.60%)	8.00%
Income Tax Expense (Benefit)		$ (17,963,000)	$ 15,600,000	$ (15,916,000)
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 7,600,000
Deferred Tax Liabilities, Net		209,121,000	218,437,000		209,121,000
Foreign Tax Credit Carry-forwards					7,600,000
Unrecognized Tax Benefits		18,680,000	12,467,000	12,863,000	18,680,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate		20,800,000			20,800,000
Unrecognized Tax Benefits, Interest on Income Taxes Accrued		2,500,000	1,400,000		2,500,000
Unrecognized Tax Benefits, Interest on Income Taxes Expense		1,100,000	(300,000)	$ 300,000
Other Assets, Current		$ 13,700,000	$ 6,100,000		$ 13,700,000