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Fair Value Measurements - Summary of Reconciliation of Beginning and Ending Balances for Fair Valued Investments (Details) - Level 3 - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net change in unrealized appreciation (depreciation) on investments	$ 793	$ (123)
Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	860,019	718,767
Net realized gains (losses) on investments	58	6,868
Net change in unrealized appreciation (depreciation) on investments	(709)	5,300
Purchase of investments	51,521	114,428
Proceeds from sales and repayments of investments	(15,871)	(23,185)
Interest and dividend income paid-in-kind	637	547
Proceeds from loan origination fees	(537)	(771)
Accretion of loan origination fees	413	280
Accretion of original issue discount	113	23
Ending Balance	897,062	811,657
Subordinated Debt | Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	101,456	36,064
Net change in unrealized appreciation (depreciation) on investments	1,565	(5)
Purchase of investments	2,182	17,470
Interest and dividend income paid-in-kind	314	41
Proceeds from loan origination fees	(25)	(165)
Accretion of loan origination fees	22	8
Accretion of original issue discount	2
Ending Balance	102,386	53,413
First Lien Debt | Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	456,105	354,922
Net change in unrealized appreciation (depreciation) on investments	(133)	(823)
Purchase of investments	40,980	76,710
Proceeds from sales and repayments of investments	(15,699)	(4,027)
Interest and dividend income paid-in-kind	127	252
Proceeds from loan origination fees	(481)	(602)
Accretion of loan origination fees	366	238
Accretion of original issue discount	16	1
Ending Balance	481,547	428,317
Second Lien Debt | Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	182,948	158,815
Net change in unrealized appreciation (depreciation) on investments	(698)	(1,277)
Purchase of investments	5,000	15,795
Proceeds from sales and repayments of investments		(7,106)
Interest and dividend income paid-in-kind	196	254
Proceeds from loan origination fees	(31)	(4)
Accretion of loan origination fees	25	34
Accretion of original issue discount	95	22
Ending Balance	188,931	169,087
Equity | Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	117,431	165,762
Net realized gains (losses) on investments	58	6,868
Net change in unrealized appreciation (depreciation) on investments	(1,165)	7,590
Purchase of investments	3,359	4,453
Proceeds from sales and repayments of investments	(172)	(12,052)
Ending Balance	121,841	157,441
Warrant | Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	2,079	3,204
Net change in unrealized appreciation (depreciation) on investments	(278)	195
Ending Balance	$ 2,357	$ 3,399

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Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

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