Investments - ISLP Balance Sheet (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024
Investment Company, Nonconsolidated Subsidiary [Line Items]
Investments at fair value		$ 2,464,945	$ 2,431,189
Cash and cash equivalents		10,168	51,562
Foreign cash		28,188	1,963	$ 2,234
Collateral on forward currency exchange contracts		6,000	0
Deferred financing costs		4,333	4,591
Unrealized appreciation on forward currency exchange contracts		1,471	4,690
Interest receivable on investments		31,061	39,164
Total Assets		2,642,315	2,632,157
Debt	[1]	1,451,204	1,390,270
Interest payable on debt		11,610	13,860
Unrealized depreciation on forward currency exchange contracts		39	1,185
Distributions payable to members		0	29,053
Accounts payable and accrued expenses		15,751	14,771
Total liabilities		1,497,811	1,492,485
Total members' equity		1,144,504	1,139,672
Total Liabilities and Total Net Assets		2,642,315	2,632,157
Investments, amortized cost		2,456,064	2,446,990
Foreign cash, cost		28,476	2,640
International Senior Loan Program, LLC
Investment Company, Nonconsolidated Subsidiary [Line Items]
Investments at fair value		657,867	655,804
Cash and cash equivalents		16,513	7,610
Foreign cash		9,976	21,243
Collateral on forward currency exchange contracts		14	14
Deferred financing costs		1,888	2,138
Unrealized appreciation on forward currency exchange contracts		0	4,237
Interest receivable on investments		14,613	13,854
Total Assets		700,871	704,900
Debt		301,937	297,634
Subordinated notes payable to members		300,049	297,240
Interest payable on debt		5,182	5,279
Interest payable on subordinated notes payable to members		9,242	20,204
Unrealized depreciation on forward currency exchange contracts		1,088	0
Distributions payable to members		1,186	550
Accounts payable and accrued expenses		291	429
Total liabilities		618,975	621,336
Total members' equity		81,896	83,564
Total Liabilities and Total Net Assets		700,871	704,900
Investments, amortized cost		671,593	683,538
Foreign cash, cost		10,050	21,972
Accumulated amortization		$ 3,292	$ 3,042

[1] Carrying value represents aggregate principal amount outstanding less unamortized debt issuance costs.