COMMITMENTS - Warranties (Details)	12 Months Ended
Jan. 31, 2020
Minimum
Warranty period	9 months
Maximum
Warranty period	24 months

Represents the information pertaining to warranty provisions covering defects in equipment, materials etc.. after the completion of construction.

No definition available.

Name:	agx_WarrantyPeriodForConstructionContracts
Namespace Prefix:	agx_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration