Joint Ventures - Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
ASSETS
Investment Owned, at Fair Value	$ 48,413,196		$ 48,908,608
Cost	48,875,505		49,935,296
Cash and cash equivalents	1,282,347		1,351,901	$ 1,588,992		$ 617,986
Receivable for investments sold	885,993		1,297,385
Deferred financing costs	101,418		102,324
Other assets	0		5,088
Total assets	51,689,613		52,692,896
LIABILITIES
Debt (net of unamortized debt issuance costs of $85,373 and $102,290 at September 30, 2023 and December 31, 2022, respectively)	23,013,800		26,493,658
Distribution payable	226,180		198,736
Total liabilities	25,539,950		30,007,831
MEMBERS’ EQUITY
Members’ Equity	10,366		9,226
Total net assets	26,149,663	$ 23,795,639	22,685,065	$ 22,378,576	$ 20,970,712	$ 12,854,820
Total liabilities and net assets	51,689,613		52,692,896
Nonconsolidated Investee | BCRED Emerald JV LP
ASSETS
Investment Owned, at Fair Value	5,688,037		6,143,310
Cost	5,703,039		6,225,186
Cash and cash equivalents	139,689		123,112
Interest receivable	47,349		67,094
Receivable for investments sold	23,009		195,023
Deferred financing costs	16,420		12,664
Other assets	0		65
Total assets	5,914,504		6,541,268
LIABILITIES
Debt (net of unamortized debt issuance costs of $85,373 and $102,290 at September 30, 2023 and December 31, 2022, respectively)	3,023,356		3,377,064
Distribution payable	110,498		91,832
Payable for investments purchased and other liabilities	78,077		308,750
Total liabilities	3,211,931		3,777,646
MEMBERS’ EQUITY
Members’ Equity	2,702,573		2,763,622
Total net assets	2,702,573		2,763,622
Total liabilities and net assets	5,914,504		6,541,268
Nonconsolidated Investee | BCRED Verdelite JV LP
ASSETS
Investment Owned, at Fair Value	433,763		490,615
Cost	427,437		495,472
Cash and cash equivalents	7,910		2,767
Interest receivable	2,713		4,539
Receivable for investments sold	7,600		1,624
Deferred financing costs	159		0
Total assets	452,145		499,545
LIABILITIES
Debt (net of unamortized debt issuance costs of $85,373 and $102,290 at September 30, 2023 and December 31, 2022, respectively)	262,600		365,000
Distribution payable	17,825		0
Payable for investments purchased and other liabilities	29,481		2,342
Total liabilities	309,906		367,342
MEMBERS’ EQUITY
Members’ Equity	142,239		132,203
Total net assets	142,239		132,203
Total liabilities and net assets	$ 452,145		$ 499,545