Subsequent Events (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Apr. 30, 2013
Subsequent Events (Textual) [Abstract]
Working capital advancements to variable interest entity	$ 3.7

Working capital advancements to variable interest entity.

No definition available.

Name:	agx_WorkingCapitalAdvancementsToVariableInterestEntity
Namespace Prefix:	agx_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration