Consolidated Statements of Operations (Parenthetical) - May. 31, 2014 - USD ($) $ in Thousands	Total	Total
Consolidated Statements of Operations
Gain (loss) from sale of assets net of tax	$ 3	$ (28)

Amount of income (loss) from a disposal of assets, net of income tax, from discontinued operation.

No definition available.

Name:	grif_IncomeLossFromSaleOfAssetsDiscontinuedOperationsNetOfTax
Namespace Prefix:	grif_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration