Investments - Schedule of Financial Information for OBDC SLF (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets
Investments at fair value	$ 12,713,348	[1],[2],[3],[4]	$ 13,010,345	[5],[6],[7]
Amortized Cost	12,632,202	[1],[2],[3],[4],[8],[9]	13,046,132	[5],[6],[7],[10],[11]
Interest receivable	112,260		108,085
Prepaid expenses and other assets	3,152		3,627
Total Assets	13,511,396		13,584,853
Liabilities
Debt	7,077,088		7,281,744
Unamortized debt issuance costs	81,492		95,647
Distributions payable	136,407		129,517
Accrued expenses and other liabilities	182,745		202,793
Total Liabilities	7,490,003		7,702,450
Members' Equity
Members' Equity	6,021,393		5,882,403		$ 5,937,877	$ 5,746,434	$ 5,977,283	$ 3,264,845	$ 1,472,579	$ 680,525
Total Liabilities and Net Assets	13,511,396		13,584,853
Investment Income
Total investment income from non-controlled, non-affiliated investments	1,582,094		1,202,004		1,021,403
Expenses
Interest expense	436,306		307,539		219,132
Professional fees	15,532		14,709		15,071
Total Operating Expenses	815,724		639,476		527,257
Net Investment Income (Loss) Before Taxes	766,370		562,528		494,146
Tax expense (benefit)	12,759		5,810		4,009
Net Investment Income (Loss) After Taxes	753,611		556,718		490,137
Net Realized and Change in Unrealized Gain (Loss) on Investments
Net change in unrealized gain (loss) on investments	92,946		(94,509)		179,824
Net realized gain on investments	(53,245)		4,146		(45,079)
Total Net Realized and Change in Unrealized Gain (Loss)	39,701		(90,363)		134,745
Net Increase (Decrease) in Net Assets Resulting from Operations	793,312		466,355		624,882
OBDC Senior Loan Fund
Assets
Investments at fair value	1,087,898		997,385
Amortized Cost	1,101,110		1,033,388
Cash	37,617		27,914
Interest receivable	7,734		3,920
Prepaid expenses and other assets	6,992		6,108
Total Assets	1,140,241		1,035,327
Liabilities
Debt	721,953		685,265
Unamortized debt issuance costs	4,930		6,117
Distributions payable	14,832		11,095
Accrued expenses and other liabilities	11,701		8,703
Total Liabilities	748,486		705,063
Members' Equity
Members' Equity	391,755		330,264
Total Liabilities and Net Assets	1,140,241		1,035,327
Investment Income
Interest income	110,439		63,220		30,836
Other income	678		2,599		344
Total investment income from non-controlled, non-affiliated investments	111,117		65,819		31,180
Expenses
Interest expense	52,148		25,182		9,745
Professional fees	1,415		935		797
Total Operating Expenses	53,563		26,117		10,542
Net Investment Income (Loss) Before Taxes	57,554		39,702		20,638
Tax expense (benefit)	832		260		731
Net Investment Income (Loss) After Taxes	56,722		39,442		19,907
Net Realized and Change in Unrealized Gain (Loss) on Investments
Net change in unrealized gain (loss) on investments	22,791		(32,078)		663
Net realized gain on investments	(4,131)		27		207
Total Net Realized and Change in Unrealized Gain (Loss)	18,660		(32,051)		870
Net Increase (Decrease) in Net Assets Resulting from Operations	$ 75,382		$ 7,391		$ 20,777

[1] Unless otherwise indicated, loan contains a variable rate structure and may be subject to an interest rate floor. Variable rate loans bear interest at a rate that may be determined by reference to either the Secured Overnight Financing Rate ("SOFR" or "S," which can include one-, three- or six- month SOFR), Euro Interbank Offered Rate (“EURIBOR”), Great Britain Pound London Interbank Offered Rate (“GBPLIBOR” or “G”, which can include three- or six-month GBPLIBOR), SONIA ("SONIA” or "SA") or an alternate base rate (which can include the Federal Funds Effective Rate or the Prime Rate), at the borrower’s option, and which reset periodically based on the terms of the loan agreement.

[2] Unless otherwise indicated, all investments are considered Level 3 investments.

[3] Unless otherwise indicated, the Company’s portfolio companies are pledged as collateral supporting the amounts outstanding under the Revolving Credit Facility, SPV Asset Facility and CLOs. See Note 6 “Debt”.

[4] Certain portfolio company investments are subject to contractual restrictions on sales. Refer to footnote 26 for additional information on our restricted securities.

[5] Certain portfolio company investments are subject to contractual restrictions on sales. Refer to footnote 28 for additional information on our restricted securities.

[6] Unless otherwise indicated, all investments are considered Level 3 investments.

[7] Unless otherwise indicated, the Company’s portfolio companies are pledged as collateral supporting the amounts outstanding under the Revolving Credit Facility, SPV Asset Facilities and CLOs. See Note 6 “Debt”.

[8] As of December 31, 2023, the net estimated unrealized loss for U.S. federal income tax purposes was $0.4 million based on a tax cost basis of $12.7 billion. As of December 31, 2023, the estimated aggregate gross unrealized loss for U.S. federal income tax purposes was $325.3 million and the estimated aggregate gross unrealized gain for U.S. federal income tax purposes was $324.9 million.

[9] The amortized cost represents the original cost adjusted for the amortization or accretion of premium or discount, as applicable, on debt investments using the effective interest method.

[10] As of December 31, 2022, the net estimated unrealized loss for U.S. federal income tax purposes was $126.2 million based on a tax cost basis of $13.1 billion. As of December 31, 2022, the estimated aggregate gross unrealized loss for U.S. federal income tax purposes was $382.2 million and the estimated aggregate gross unrealized gain for U.S. federal income tax purposes was $256.0 million.

[11] The amortized cost represents the original cost adjusted for the amortization or accretion of premium or discount , as applicable, on debt investments using the effective interest method.