DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION (Details)	9 Months Ended
Oct. 31, 2018	Oct. 31, 2017
GPS
Description of the Business
Consolidated revenues by subsidiaries	61.00%	89.00%

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