Name:	neog_GoodwillAndOtherIntangibleAssetLineItems
Namespace Prefix:	neog_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(2)

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

+ Details

Name:	us-gaap_AmortizationOfIntangibleAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of amortization expense expected to be recognized during the next fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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)(3)

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

+ Details

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

- Definition

Amount of amortization expense expected to be recognized during the fifth fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

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

- Definition

Amount of amortization expense expected to be recognized during the fourth fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

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

- Definition

Amount of amortization expense expected to be recognized during the third fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

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

- Definition

Amount of amortization expense expected to be recognized during the second fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

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

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount (original costs adjusted for previously recognized amortization and impairment) as of the balance sheet date of rights not otherwise specified in the taxonomy having a projected indefinite period of benefit.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)

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

+ Details

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

Goodwill and Other Intangible Asset Table - Additional Information (Detail) (USD $)	12 Months Ended
	May 31, 2014	May 31, 2013	May 31, 2012
Goodwill And Other Intangible Asset [Line Items]
Non-amortizable intangible assets	$ 9,682,000	$ 6,660,000
Amortization expense for intangible assets	3,797,000	2,994,000	2,527,000
Estimated amortization expense for period, 2015	4,158,000
Estimated amortization expense for period, 2016	3,916,000
Estimated amortization expense for period, 2017	3,770,000
Estimated amortization expense for period, 2018	3,552,000
Estimated amortization expense for period, 2019	2,955,000
Minimum
Goodwill And Other Intangible Asset [Line Items]
Finite lived intangible assets, useful life	5 years
Maximum
Goodwill And Other Intangible Asset [Line Items]
Finite lived intangible assets, useful life	20 years
Licenses
Goodwill And Other Intangible Asset [Line Items]
Non-amortizable intangible assets	569,000	569,000
Licenses \| Minimum
Goodwill And Other Intangible Asset [Line Items]
Finite lived intangible assets, useful life	5 years
Licenses \| Maximum
Goodwill And Other Intangible Asset [Line Items]
Finite lived intangible assets, useful life	20 years
Trademarks
Goodwill And Other Intangible Asset [Line Items]
Non-amortizable intangible assets	7,889,000	4,867,000
Other Intangible Assets
Goodwill And Other Intangible Asset [Line Items]
Non-amortizable intangible assets	$ 1,224,000	$ 1,224,000
Finite lived intangible assets, useful life	12 years	12 years
Noncompete Agreements
Goodwill And Other Intangible Asset [Line Items]
Finite lived intangible assets, useful life	5 years
Patents \| Minimum
Goodwill And Other Intangible Asset [Line Items]
Finite lived intangible assets, useful life	5 years
Patents \| Maximum
Goodwill And Other Intangible Asset [Line Items]
Finite lived intangible assets, useful life	20 years
Customer Relationships
Goodwill And Other Intangible Asset [Line Items]
Finite lived intangible assets, useful life	12 years	12 years
Customer Relationships \| Minimum
Goodwill And Other Intangible Asset [Line Items]
Finite lived intangible assets, useful life	12 years
Customer Relationships \| Maximum
Goodwill And Other Intangible Asset [Line Items]
Finite lived intangible assets, useful life	20 years