Amortizable of Intangible Assets (Detail) - USD ($) $ in Thousands	May 31, 2016	May 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 74,162	$ 57,897
Less Accumulated Amortization	24,807	20,523
Net Carrying Amount	49,355	37,374
Licenses
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,189	4,919
Less Accumulated Amortization	1,782	1,630
Net Carrying Amount	3,407	3,289
Noncompete Agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	491	428
Less Accumulated Amortization	193	124
Net Carrying Amount	298	304
Patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	8,040	7,701
Less Accumulated Amortization	3,631	3,087
Net Carrying Amount	4,409	4,614
Customer-based intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	48,186	38,616
Less Accumulated Amortization	17,277	14,446
Net Carrying Amount	30,909	24,170
Other product and service-related intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	12,256	6,233
Less Accumulated Amortization	1,924	1,236
Net Carrying Amount	$ 10,332	$ 4,997

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=66006027&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_CustomerRelatedIntangibleAssetsMember
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: