XML 28 R29.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Description of the Business and Basis of Presentation - Additional Information (Detail) | 9 Months Ended
--- | ---
Oct. 31, 2014 Category | Oct. 31, 2013 Category
Accounting Policies [Abstract] |  |
Number of categories | 2 | 2

X
- Definition Number of categories. + References No definition available. + Details
Name: | agx_NumberOfCategories
Namespace Prefix: | agx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AccountingPoliciesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration