REO (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Real estate owned, gross	$ 1,416	$ 2,559
Less: Valuation allowance	574	627
Real estate owned, net	842	1,932
Valuation allowance, beginning	627	653
Provision charged to expense	113	276
Reduction due to disposal	(166)	(302)
Valuation allowance, ending	$ 574	$ 627

No definition available.

Name:	grrb_OtherRealEstateAndForeclosedAssetsGross
Namespace Prefix:	grrb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of other real estate and foreclosed assets. Other real estate may include real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. Foreclosed assets include all assets obtained in full or partial satisfaction of a debt arrangement through foreclosure proceedings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10(4))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

For each period for which an income statement is required, disclosure of the changes in the allowance, including balances at end of period.

+ References

+ Details

Name:	us-gaap_RealEstateOwnedValuationAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the valuation allowance for real estate owned that was applied in the period against the carrying amount of real estate owned that was sold, written down or written off.

+ References

+ Details

Name:	us-gaap_RealEstateOwnedValuationAllowanceAmountsApplied
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of expense recognized in the income statement for a decrease in valuation of real estate owned (REO).

+ References

+ Details

Name:	us-gaap_RealEstateOwnedValuationAllowanceProvision1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration