CASH, CASH EQUIVALENTS AND INVESTMENTS - Concentration Risk (Details)	Apr. 30, 2026	Jan. 31, 2026
CASH, CASH EQUIVALENTS AND INVESTMENTS
Percentage of cash and cash equivalents and investments held by foreign subsidiaries	11.00%	10.00%

Percentage of entity's cash and cash equivalents and investments held by foreign subsidiaries.

No definition available.

Name:	agx_PercentageOfCashAndCashEquivalentsAndInvestmentsHeldByForeignSubsidiaries
Namespace Prefix:	agx_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant