REVENUES FROM CONTRACTS WITH CUSTOMERS - Variable Consideration (Details) - USD ($) $ in Millions	Apr. 30, 2025	Jan. 31, 2025
REVENUES FROM CONTRACTS WITH CUSTOMERS
Amounts of unpriced change orders included in transaction prices	8.9	8.0

Amounts of unpriced change orders included in transaction prices.

No definition available.

Name:	agx_NPricedChangeOrdersIncludedInTransactionPrices
Namespace Prefix:	agx_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant