Note 16 - Condensed Consolidating Financial Information of Guarantor Subsidiaries - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Thousands	Feb. 28, 2017	May 31, 2016	Feb. 29, 2016	May 31, 2015
Current Assets:
Cash and cash equivalents	$ 10,035	$ 10,263	$ 12,190	$ 18,363
Accounts receivable, net	64,120	62,043
Intercompany receivable
Inventories, net	48,870	46,894
Prepaid expenses and other current assets	8,825	8,479
Total current assets	131,850	127,679
Property and equipment, net	76,792	76,015
Investment in subsidiaries
Goodwill	854,736	857,023		842,258
Other intangible assets, net	589,264	633,097
Other assets	11,229	13,819
Total assets	1,663,871	1,707,633
Current Liabilities:
Accounts payable	21,263	22,229
Intercompany payable
Accrued interest and interest rate swap liability	7,373	18,869
Accrued expenses and other current liabilities	23,892	22,009
Income taxes payable	3,476	2,585
Deferred revenue, current portion	3,220	2,864
Long-term Debt, Current Maturities	26,718	6,806
Total current liabilities	85,942	75,362
Long-term debt, excluding current portion	1,010,427	1,007,948
Deferred income tax liabilities	201,509	222,357
Other long-term liabilities	55,566	57,420
Total liabilities	1,353,444	1,363,087
Equity:
Shareholders' equity of Immucor, Inc.	303,458	340,223
Noncontrolling interest	6,969	4,323
Total equity	310,427	344,546		383,681
Total liabilities and equity	1,663,871	1,707,633
Consolidation, Eliminations [Member]
Current Assets:
Cash and cash equivalents
Accounts receivable, net
Intercompany receivable	(156,483)	(148,502)
Inventories, net	(2,235)	(1,695)
Prepaid expenses and other current assets
Total current assets	(158,718)	(150,197)
Property and equipment, net
Investment in subsidiaries	(217,112)	(234,503)
Goodwill
Other intangible assets, net
Other assets	(9,871)	(9,728)
Total assets	(385,701)	(394,428)
Current Liabilities:
Accounts payable
Intercompany payable	(156,483)	(148,502)
Accrued interest and interest rate swap liability
Accrued expenses and other current liabilities
Income taxes payable
Deferred revenue, current portion
Long-term Debt, Current Maturities
Total current liabilities	(156,483)	(148,502)
Long-term debt, excluding current portion
Deferred income tax liabilities	(863)	(654)
Other long-term liabilities	(9,871)	(9,728)
Total liabilities	(167,217)	(158,884)
Equity:
Shareholders' equity of Immucor, Inc.	(218,484)	(235,544)
Noncontrolling interest
Total equity	(218,484)	(235,544)
Total liabilities and equity	(385,701)	(394,428)
Parent Company [Member] | Reportable Legal Entities [Member]
Current Assets:
Cash and cash equivalents	4,095	4,058	2,680	7,080
Accounts receivable, net	29,687	28,314
Intercompany receivable	98,999	98,375
Inventories, net	19,630	19,853
Prepaid expenses and other current assets	2,788	3,381
Total current assets	155,199	153,981
Property and equipment, net	41,865	39,724
Investment in subsidiaries	194,061	211,451
Goodwill	744,044	744,044
Other intangible assets, net	453,920	489,871
Other assets	28,268	30,346
Total assets	1,617,357	1,669,417
Current Liabilities:
Accounts payable	10,244	10,622
Intercompany payable	8,643	18,293
Accrued interest and interest rate swap liability	7,373	18,869
Accrued expenses and other current liabilities	12,654	10,700
Income taxes payable	30,026	30,190
Deferred revenue, current portion	2,204	1,785
Long-term Debt, Current Maturities	26,633	6,634
Total current liabilities	97,777	97,093
Long-term debt, excluding current portion	1,010,427	1,007,888
Deferred income tax liabilities	187,284	201,489
Other long-term liabilities	18,411	22,724
Total liabilities	1,313,899	1,329,194
Equity:
Shareholders' equity of Immucor, Inc.	303,458	340,223
Noncontrolling interest
Total equity	303,458	340,223
Total liabilities and equity	1,617,357	1,669,417
Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Current Assets:
Cash and cash equivalents	(193)	(187)	(518)	(263)
Accounts receivable, net	6,253	5,866
Intercompany receivable	39,091	26,311
Inventories, net	18,993	17,321
Prepaid expenses and other current assets	240	449
Total current assets	64,384	49,760
Property and equipment, net	12,769	14,713
Investment in subsidiaries	20,032	20,033
Goodwill	62,771	62,771
Other intangible assets, net	87,570	92,500
Other assets	364	274
Total assets	247,890	240,051
Current Liabilities:
Accounts payable	4,911	5,517
Intercompany payable	134,286	117,516
Accrued interest and interest rate swap liability
Accrued expenses and other current liabilities	4,850	5,230
Income taxes payable	(29,609)	(29,838)
Deferred revenue, current portion
Long-term Debt, Current Maturities	85	172
Total current liabilities	114,523	98,597
Long-term debt, excluding current portion		60
Deferred income tax liabilities	3,710	7,070
Other long-term liabilities	45,709	43,099
Total liabilities	163,942	148,826
Equity:
Shareholders' equity of Immucor, Inc.	83,948	91,225
Noncontrolling interest
Total equity	83,948	91,225
Total liabilities and equity	247,890	240,051
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Current Assets:
Cash and cash equivalents	5,796	6,356	$ 10,028	$ 11,546
Accounts receivable, net	28,180	27,863
Intercompany receivable	18,687	24,710
Inventories, net	12,482	11,415
Prepaid expenses and other current assets	5,797	4,649
Total current assets	70,942	74,993
Property and equipment, net	21,484	20,934
Investment in subsidiaries	3,019	3,019
Goodwill	47,816	50,103
Other intangible assets, net	28,959	31,906
Other assets	489	360
Total assets	172,709	181,315
Current Liabilities:
Accounts payable	5,144	5,346
Intercompany payable	13,554	12,693
Accrued interest and interest rate swap liability
Accrued expenses and other current liabilities	6,376	6,075
Income taxes payable	3,059	2,233
Deferred revenue, current portion	1,016	1,079
Long-term Debt, Current Maturities
Total current liabilities	29,149	27,426
Long-term debt, excluding current portion
Deferred income tax liabilities	7,707	8,245
Other long-term liabilities	1,317	1,325
Total liabilities	38,173	36,996
Equity:
Shareholders' equity of Immucor, Inc.	134,536	144,319
Noncontrolling interest
Total equity	134,536	144,319
Total liabilities and equity	172,709	181,315
Immucor Inc and Subsidiaries [Member] | Reportable Legal Entities [Member]
Current Assets:
Cash and cash equivalents	9,698	10,227
Accounts receivable, net	64,120	62,043
Intercompany receivable	294	894
Inventories, net	48,870	46,894
Prepaid expenses and other current assets	8,825	8,479
Total current assets	131,807	128,537
Property and equipment, net	76,118	75,371
Investment in subsidiaries
Goodwill	854,631	856,918
Other intangible assets, net	570,449	614,277
Other assets	19,250	21,252
Total assets	1,652,255	1,696,355
Current Liabilities:
Accounts payable	20,299	21,485
Intercompany payable
Accrued interest and interest rate swap liability	7,373	18,869
Accrued expenses and other current liabilities	23,880	22,005
Income taxes payable	3,476	2,585
Deferred revenue, current portion	3,220	2,864
Long-term Debt, Current Maturities	26,718	6,806
Total current liabilities	84,966	74,614
Long-term debt, excluding current portion	1,010,427	1,007,948
Deferred income tax liabilities	197,838	216,150
Other long-term liabilities	55,566	57,420
Total liabilities	1,348,797	1,356,132
Equity:
Shareholders' equity of Immucor, Inc.	303,458	340,223
Noncontrolling interest
Total equity	303,458	340,223
Total liabilities and equity	1,652,255	1,696,355
VIE and VIE Eliminations [Member] | Reportable Legal Entities [Member]
Current Assets:
Cash and cash equivalents	337	36
Accounts receivable, net
Intercompany receivable	(294)	(894)
Inventories, net
Prepaid expenses and other current assets
Total current assets	43	(858)
Property and equipment, net	674	644
Investment in subsidiaries
Goodwill	105	105
Other intangible assets, net	18,815	18,820
Other assets	(8,021)	(7,433)
Total assets	11,616	11,278
Current Liabilities:
Accounts payable	964	744
Intercompany payable
Accrued interest and interest rate swap liability
Accrued expenses and other current liabilities	12	4
Income taxes payable
Deferred revenue, current portion
Long-term Debt, Current Maturities
Total current liabilities	976	748
Long-term debt, excluding current portion
Deferred income tax liabilities	3,671	6,207
Other long-term liabilities
Total liabilities	4,647	6,955
Equity:
Shareholders' equity of Immucor, Inc.
Noncontrolling interest	6,969	4,323
Total equity	6,969	4,323
Total liabilities and equity	$ 11,616	$ 11,278