Fair Value - Summary of Changes in Fair Value of Level 3 Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2025		Dec. 31, 2024
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance	$ 1,956,286		$ 2,110,586
Net realized gain (loss)	22		(2,068)
Net change in unrealized gain (loss)	$ (1,163)		$ 1,531
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net Change In Unrealized Gain Loss On Investments		Net Change In Unrealized Gain Loss On Investments
Purchase of investment securities	$ 196,788	[1]	$ 479,716	[2]
Proceeds from dispositions of investment securities	(196,288)		(633,479)
Transfers in/out of Level 3	0		0
Closing balance	1,955,645		1,956,286
Net change in unrealized gain (loss)	$ 1,375		$ 5,687
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net Change In Unrealized Gain Loss On Investments		Net Change In Unrealized Gain Loss On Investments
Senior Secured Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance	$ 1,117,118		$ 1,277,539
Net realized gain (loss)	30		(1,400)
Net change in unrealized gain (loss)	(2,905)		(3,598)
Purchase of investment securities	188,200	[1]	411,598	[2]
Proceeds from dispositions of investment securities	(185,838)		(567,021)
Transfers in/out of Level 3	0		0
Closing balance	1,116,605		1,117,118
Net change in unrealized gain (loss)	(367)		1,533
Equipment Financing [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance	181,016		256,819
Net realized gain (loss)	(8)		0
Net change in unrealized gain (loss)	(6,493)		(12,646)
Purchase of investment securities	2,734	[1]	2,852	[2]
Proceeds from dispositions of investment securities	(10,450)		(66,009)
Transfers in/out of Level 3	0		0
Closing balance	166,799		181,016
Net change in unrealized gain (loss)	(6,493)		(12,646)
Preferred Equity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance	31,682		3,801
Net realized gain (loss)	0		0
Net change in unrealized gain (loss)	(113)		49
Purchase of investment securities	770	[1]	27,832	[2]
Proceeds from dispositions of investment securities	0		0
Transfers in/out of Level 3	0		0
Closing balance	32,339		31,682
Net change in unrealized gain (loss)	(113)		49
Common Equity/Equity Interests/Warrants [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance	626,470		572,427
Net realized gain (loss)	0		(668)
Net change in unrealized gain (loss)	8,348		17,726
Purchase of investment securities	5,084	[1]	37,434	[2]
Proceeds from dispositions of investment securities	0		(449)
Transfers in/out of Level 3	0		0
Closing balance	639,902		626,470
Net change in unrealized gain (loss)	$ 8,348		$ 16,751

[1] Includes PIK capitalization and accretion of discount.

[2] Includes PIK capitalization and accretion of discount