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Commitments - Additional Information (Detail) (USD $) | 12 Months Ended
--- | ---
Jan. 31, 2014 | Jan. 31, 2013 | Jan. 31, 2012
Commitments [Line Items] |  |  |
Rent incurred on construction projects included in the costs of revenues | $ 3,612,000 | $ 7,567,000 | $ 4,386,000
Selling, General and Administrative Expenses [Member] |  |  |
Commitments [Line Items] |  |  |
Rent expense included in selling, general and administrative expenses of continuing operations | $ 171,000 | $ 390,000 | $ 443,000

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Namespace Prefix: | agx_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Rent incurred on construction projects included in the costs of revenues of continuing operations. + References No definition available. + Details
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Namespace Prefix: | agx_
Data Type: | xbrli:monetaryItemType
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Period Type: | duration

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- Definition No authoritative reference available. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41499-112717 + Details
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