Stockholders' Equity (Details 6) (Nonvested Options, USD $) In Thousands, unless otherwise specified	May 31, 2014
Nonvested Options
Unrecognized compensation expense related to non-vested stock options that will be recognized during future periods
Balance of Fiscal 2014	$ 125
Fiscal 2015	153
Fiscal 2016	$ 33

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