COMMITMENTS AND CONTINGENCIES (Details) - USD ($)	Feb. 28, 2011	Apr. 30, 2009
Commitments and Contingencies Disclosure [Abstract]
Net capital cost value		$ 5,000,000
Obligation under consent order	$ 0
Net capital cost value in proposed remedial action plan	$ 10,000,000

Amount of net capital cost value in Proposed Remedial Action Plan as of the reporting date.

No definition available.

Name:	gff_NetCapitalCostValueInProposedRemediaActionPlan
Namespace Prefix:	gff_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant