Stockholders' Equity (Details 5) - Nonvested Options $ in Thousands	May. 31, 2015 USD ($)
Unrecognized compensation expense related to non-vested stock options that will be recognized during future periods
Fiscal 2015	$ 82
Fiscal 2016	79
Fiscal 2017	$ 19

Amount of unrecognized compensation expense related to non-vested stock options that will be recognized over remainder of the fiscal year following the latest fiscal year ended.

No definition available.

Name:	grif_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptionsAmountOfRecognitionDuringRemainderOfFiscalYear
Namespace Prefix:	grif_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant