Debt Instrument, Credit Spread Adjustment

No definition available.

Name:	bbdc_DebtInstrumentCreditSpreadAdjustment
Namespace Prefix:	bbdc_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Line Of Credit Facility, Change In Reallocation Of Commitments

+ References

No definition available.

+ Details

Name:	bbdc_LineOfCreditFacilityChangeInReallocationOfCommitments
Namespace Prefix:	bbdc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

+ Details

Name:	us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

+ Details

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

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481674/830-30-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 855
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483399/855-10-50-2

+ Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DebtInstrumentAxis=bbdc_February2019CreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	bbdc_InterestPeriodAxis=bbdc_InterestPeriodOfOneMonthMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	bbdc_InterestPeriodAxis=bbdc_InterestPeriodOfThreeMonthMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	bbdc_InterestPeriodAxis=bbdc_InterestPeriodOfSixMonthMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ExternalCreditRatingByGroupingAxis=us-gaap_ExternalCreditRatingInvestmentGradeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

SUBSEQUENT EVENTS (Details)			1 Months Ended	3 Months Ended		9 Months Ended
SUBSEQUENT EVENTS (Details)	Nov. 06, 2024 $ / shares	Nov. 05, 2024 USD ($)	Feb. 28, 2019 USD ($)	Sep. 30, 2024 USD ($) $ / shares	Sep. 30, 2023 $ / shares	Sep. 30, 2024 USD ($) $ / shares	Sep. 30, 2023 $ / shares	Dec. 31, 2023 USD ($)	Apr. 01, 2022 USD ($)	Feb. 25, 2022 USD ($)	Nov. 04, 2021 USD ($)
Subsequent Event [Line Items]
Quarterly dividend declared (usd per share) \| $ / shares				$ 0.26	$ 0.26	$ 0.78	$ 0.76
February 21, 2019 \| Line of Credit
Subsequent Event [Line Items]
Debt instrument, basis spread on variable rate			2.25%
Commitment aggregate amount			$ 800,000,000	$ 1,065,000,000		$ 1,065,000,000		$ 1,065,000,000	$ 1,065,000,000	$ 965,000,000	$ 875,000,000
February 21, 2019 \| Line of Credit \| Interest Period Of One Month
Subsequent Event [Line Items]
Debt instrument, credit spread adjustment			0.0010
February 21, 2019 \| Line of Credit \| Interest Period Of Three Month
Subsequent Event [Line Items]
Debt instrument, credit spread adjustment			0.0015
February 21, 2019 \| Line of Credit \| Interest Period Of Six Month
Subsequent Event [Line Items]
Debt instrument, credit spread adjustment			0.0025
February 21, 2019 \| Line of Credit \| External Credit Rating, Investment Grade
Subsequent Event [Line Items]
Debt instrument, basis spread on variable rate			2.00%
Subsequent Event
Subsequent Event [Line Items]
Quarterly dividend declared (usd per share) \| $ / shares	$ 0.26
Subsequent Event \| February 21, 2019 \| Line of Credit
Subsequent Event [Line Items]
Debt instrument, basis spread on variable rate		1.875%
Commitment aggregate amount		$ 825,000,000
Reallocation of loans from revolving commitments to term loan commitments		$ 100,000,000
Subsequent Event \| February 21, 2019 \| Line of Credit \| Interest Period Of One Month
Subsequent Event [Line Items]
Debt instrument, credit spread adjustment		0.0010