Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash Flows from Operating Activities
Net Increase (Decrease) in Net Assets Resulting from Operations	$ 793,312	$ 466,355	$ 624,882
Adjustments to reconcile net increase (decrease) in net assets resulting from operations to net cash used in operating activities:
Purchases of investments, net	(2,268,603)	(2,132,632)	(7,135,785)
Proceeds from investments and investment repayments, net	2,889,840	1,926,108	5,511,556
Net amortization/accretion of premium/discount on investments	(49,349)	(41,712)	(82,000)
Payment-in-kind interest and dividends	(209,984)	(147,758)	(59,918)
Net change in unrealized (gain) loss on investments	(91,743)	88,427	(192,381)
Net change in unrealized gain (loss) on interest rate swap attributed to unsecured notes	22,681	(84,779)	(9,531)
Net change in unrealized (gains) losses on translation of assets and liabilities in foreign currencies	(5,768)	2,514	3,206
Net realized (gain) loss on investments	52,003	(5,171)	46,332
Net realized (gain) loss on foreign currency transactions relating to investments	23	3,586	(20)
Amortization of debt issuance costs	26,849	30,076	25,721
Amortization of offering costs	0	0	96
Changes in operating assets and liabilities:
(Increase) decrease in receivable for investments sold	0	0	6,316
(Increase) decrease in interest receivable	(4,175)	(26,369)	(24,608)
(Increase) decrease in receivable from a controlled affiliate	(5,269)	(13,756)	(1,606)
(Increase) decrease in prepaid expenses and other assets	475	20,089	14,792
Increase (decrease) in management fee payable	128	813	10,834
Increase (decrease) in incentive fee payable	7,755	5,220	10,172
Increase (decrease) in payables to affiliate	(2,516)	549	(725)
Increase (decrease) in accrued expenses and other liabilities	(20,048)	125,708	25,504
Net cash provided by (used in) operating activities	1,135,611	217,268	(1,227,163)
Cash Flows from Financing Activities
Borrowings on debt	1,746,479	2,531,427	5,521,730
Payments on debt	(2,007,393)	(2,220,889)	(3,697,000)
Debt issuance costs	(12,694)	(15,484)	(44,875)
Repurchases of common stock	(34,058)	(25,958)	(2,604)
Cash distributions paid to shareholders	(613,374)	(488,422)	(460,854)
Net cash provided by (used in) financing activities	(921,040)	(219,326)	1,316,397
Net increase (decrease) in cash and restricted cash, including foreign cash (restricted cash of $(9,353), $74,939 and $12,640, respectively)	214,571	(2,058)	89,234
Cash and restricted cash, including foreign cash, beginning of period (restricted cash of $96,420, $21,481 and $8,841, respectively)	445,087	447,145	357,911
Cash and restricted cash, including foreign cash, end of period (restricted cash of $87,067, $96,420 and $21,481, respectively)	659,658	445,087	447,145
Supplemental and Non-Cash Information
Interest paid during the period	396,732	234,195	166,531
Distributions declared during the period	620,264	507,822	486,868
Reinvestment of distributions during the period	0	11,951	56,033
Distributions Payable	136,407	129,517	122,068
Taxes, including excise tax, paid during the period	3,448	3,913	4,962
Restricted cash	$ 87,067	$ 96,420	$ 21,481