Line Of Credit Facility, Non-usage Fee, Percentage

No definition available.

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Namespace Prefix:	gbdc_
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Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maturity period on variable rate advances made and reported by Federal Home Loan Bank (FHLBank), in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The effective interest rate during the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Namespace Prefix:
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- Details

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- Details

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Period Type:

- Details

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Balance Type:
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- Details

Name:	us-gaap_VariableRateAxis=gbdc_EURIBORMember
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- Details

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Borrowings - MS Credit Facility II Narrative (Details) - Revolving Credit Facility - MS Credit Facility II - Line of Credit - USD ($)		6 Months Ended
	Sep. 16, 2022	Mar. 31, 2023	Feb. 01, 2019
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 75,000
Line of credit facility, non-usage fee, percentage			0.50%
Base Rate
Debt Instrument [Line Items]
Line of credit facility, interest rate during period	2.05%
London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Federal home loan bank, advances, maturity period, variable rate		1 month
EURIBOR
Debt Instrument [Line Items]
Federal home loan bank, advances, maturity period, variable rate		1 month
Canadian Dollar Offered Rate
Debt Instrument [Line Items]
Federal home loan bank, advances, maturity period, variable rate		1 month