Schedule of Total Revenue Percentages Contributable to Specific Government Agencies (Detail) (Government Contracts Concentration Risk)	12 Months Ended
Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
US DoD [Member]
Segment Reporting Information [Line Items]
Percentage of sales	68.00%	69.00%	72.00%
U.S. Government
Segment Reporting Information [Line Items]
Percentage of sales	78.00%	81.00%	83.00%
U.S. Army
Segment Reporting Information [Line Items]
Percentage of sales	19.00%	23.00%	25.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 21

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13537-108611

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

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-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

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-URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13531-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

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