ACCOUNTS AND NOTES RECEIVABLE (Details) $ in Millions	Apr. 30, 2020 USD ($)
ACCOUNTS AND NOTES RECEIVABLE
Outstanding balances of accounts receivable and contract assets	$ 24.5

Amount of outstanding balances which includes accounts receivable and contract assets.

No definition available.

Name:	agx_InvoicesOutstandingBalanceIncludedInAccountsReceivableAndContractAssets
Namespace Prefix:	agx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant