v3.26.1
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Cash and equivalents (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Accounting Policies [Abstract]
Cash in non U.S. bank accounts
$ 38,500
$ 46,100
X
- Definition
Amount of cash in non-U.S bank accounts as of the reporting date.
+ References
No definition available.
+ Details
Name:
gff_CashInNonUsBankAccounts
Namespace Prefix:
gff_
Data Type:
xbrli:monetaryItemType
Balance Type:
debit
Period Type:
instant
X
- References
No definition available.
+ Details
Name:
us-gaap_AccountingPoliciesAbstract
Namespace Prefix:
us-gaap_
Data Type:
xbrli:stringItemType
Balance Type:
na
Period Type:
duration