Amortizable of Intangible Assets (Detail) - USD ($) $ in Thousands	May. 31, 2015	May. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 57,897	$ 54,143
Less Accumulated Amortization	20,523	17,409
Net Carrying Amount	37,374	36,734
Licenses
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	4,919	6,701
Less Accumulated Amortization	1,630	1,873
Net Carrying Amount	3,289	4,828
Noncompete Agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	428	474
Less Accumulated Amortization	124	256
Net Carrying Amount	304	218
Patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	7,701	5,990
Less Accumulated Amortization	3,087	2,746
Net Carrying Amount	4,614	3,244
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	38,616	37,145
Less Accumulated Amortization	14,446	11,915
Net Carrying Amount	24,170	25,230
Other product and service-related intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	6,233	3,833
Less Accumulated Amortization	1,236	619
Net Carrying Amount	$ 4,997	$ 3,214

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_LicensingAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_NoncompeteAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_PatentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=neog_OtherProductsAndServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: