Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
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0 Months Ended | 12 Months Ended | 12 Months Ended | 0 Months Ended | 12 Months Ended | ||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Oct. 30, 2013
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May 31, 2014
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May 31, 2013
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May 31, 2012
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May 31, 2011
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May 31, 2014
Minimum
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May 31, 2014
Maximum
|
May 31, 2014
Buildings And Improvements
Minimum
|
May 31, 2013
Buildings And Improvements
Minimum
|
May 31, 2012
Buildings And Improvements
Minimum
|
May 31, 2014
Buildings And Improvements
Maximum
|
May 31, 2013
Buildings And Improvements
Maximum
|
May 31, 2012
Buildings And Improvements
Maximum
|
May 31, 2014
Furniture, Machinery and Equipment
Minimum
|
May 31, 2013
Furniture, Machinery and Equipment
Minimum
|
May 31, 2012
Furniture, Machinery and Equipment
Minimum
|
May 31, 2014
Furniture, Machinery and Equipment
Maximum
|
May 31, 2013
Furniture, Machinery and Equipment
Maximum
|
May 31, 2012
Furniture, Machinery and Equipment
Maximum
|
May 31, 2014
Customer Relationships
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May 31, 2013
Customer Relationships
|
May 31, 2014
Customer Relationships
Minimum
|
May 31, 2014
Customer Relationships
Maximum
|
May 31, 2014
Other Intangible Assets
|
May 31, 2013
Other Intangible Assets
|
Dec. 31, 2013
Neogen Latin America
|
May 31, 2014
Neogen Latin America
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May 31, 2014
Neogen Do Brazil
|
May 31, 2014
Customer one
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Significant Accounting Policies [Line Items] | |||||||||||||||||||||||||||||
Percentage of ownership in subsidiaries | 90.00% | 90.00% | |||||||||||||||||||||||||||
Percentage of ownership in subsidiaries before capital contribution | 60.00% | ||||||||||||||||||||||||||||
Percentage of ownership in subsidiaries after capital contribution | 90.00% | ||||||||||||||||||||||||||||
Stock Split ratio | 1.5 | ||||||||||||||||||||||||||||
Account receivable percentage from major customer | 10.00% | ||||||||||||||||||||||||||||
Cash and cash equivalents | $ 40,675,000 | $ 50,032,000 | $ 49,045,000 | $ 35,844,000 | |||||||||||||||||||||||||
Short-term domestic certificates of deposit | 17,576,000 | ||||||||||||||||||||||||||||
Marketable securities, maturity period | 91 days | 1 year | |||||||||||||||||||||||||||
Commercial Paper | 18,245,000 | ||||||||||||||||||||||||||||
Marketable securities | 35,821,000 | 35,337,000 | |||||||||||||||||||||||||||
Valuation allowance for inventory | 1,425,000 | 1,250,000 | |||||||||||||||||||||||||||
Property, plant and equipment estimated useful life | 7 years | 7 years | 7 years | 39 years | 39 years | 39 years | 3 years | 3 years | 3 years | 10 years | 10 years | 10 years | |||||||||||||||||
Depreciation expense | 5,383,000 | 4,417,000 | 3,646,000 | ||||||||||||||||||||||||||
Finite lived intangible assets, useful life | 5 years | 20 years | 12 years | 12 years | 12 years | 20 years | 12 years | 12 years | |||||||||||||||||||||
Weighted-average fair value per share of stock options granted | $ 9.87 | $ 9.21 | $ 6.94 | ||||||||||||||||||||||||||
Shipping and handling costs | 7,472,000 | 6,856,000 | 5,940,000 | ||||||||||||||||||||||||||
Unremitted earnings of foreign subsidiaries | 18,262,000 | ||||||||||||||||||||||||||||
Advertising costs | $ 1,344,000 | $ 1,055,000 | $ 1,001,000 | ||||||||||||||||||||||||||
Shares excluded from computations of diluted net income per share | 48,716 | 88,912 | 78,450 |