DESCRIPTION OF THE BUSINESS (Details)	12 Months Ended
Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
GPS
Description of the Business
Consolidated revenues by subsidiaries	90.00%	98.00%	96.00%

Represents the entity's revenue contributed to the parent entity as a percentage of the parent entity's total revenue.

No definition available.

Name:	agx_RevenueContributedToParentAsPercentageOfTotalParentRevenue
Namespace Prefix:	agx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration