REVENUES FROM CONTRACTS WITH CUSTOMERS - Variable Consideration (Details) - USD ($) $ in Millions	Jul. 31, 2024	Jan. 31, 2024
REVENUES FROM CONTRACTS WITH CUSTOMERS
Amounts of unpriced change orders included in transaction prices	11.7	8.4

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