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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		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net change in unrealized appreciation (depreciation) on investments	$ (36,403)	$ 17,067	$ (42,882)	$ 33,223
Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance			718,767	742,869
Net realized gains (losses) on investments			65,220	13,673
Net change in unrealized appreciation (depreciation) on investments			(67,774)	32,019
Purchase of investments			267,950	245,544
Proceeds from sales and repayments of investments			(128,255)	(319,036)
Interest and dividend income paid-in-kind			1,327	3,437
Proceeds from loan origination fees			(1,869)	(1,949)
Accretion of loan origination fees			1,094	1,833
Accretion of original issue discount			137	734
Ending Balance	856,597	719,124	856,597	719,124
Subordinated Debt | Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance			36,064	107,911
Net change in unrealized appreciation (depreciation) on investments			1,213	(308)
Purchase of investments			44,469	18,500
Proceeds from sales and repayments of investments				(57,039)
Interest and dividend income paid-in-kind			273	81
Proceeds from loan origination fees			(300)	(80)
Accretion of loan origination fees			40	387
Ending Balance	81,759	69,452	81,759	69,452
First Lien Debt | Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance			354,922	187,353
Net change in unrealized appreciation (depreciation) on investments			(1,281)	(1,182)
Purchase of investments			166,279	172,506
Proceeds from sales and repayments of investments			(31,574)	(61,008)
Interest and dividend income paid-in-kind			481	109
Proceeds from loan origination fees			(1,454)	(1,765)
Accretion of loan origination fees			943	985
Accretion of original issue discount			18
Ending Balance	488,334	296,998	488,334	296,998
Second Lien Debt | Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance			158,815	332,154
Net change in unrealized appreciation (depreciation) on investments			(13,048)	(1,213)
Purchase of investments			49,498	43,850
Proceeds from sales and repayments of investments			(18,731)	(177,719)
Interest and dividend income paid-in-kind			573	3,142
Proceeds from loan origination fees			(115)	(104)
Accretion of loan origination fees			111	461
Accretion of original issue discount			119	734
Ending Balance	177,222	201,305	177,222	201,305
Equity | Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance			165,762	112,836
Net realized gains (losses) on investments			65,220	13,673
Net change in unrealized appreciation (depreciation) on investments			(54,102)	34,066
Purchase of investments			7,704	10,688
Proceeds from sales and repayments of investments			(77,950)	(23,270)
Interest and dividend income paid-in-kind				105
Ending Balance	106,634	148,098	106,634	148,098
Warrant | Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance			3,204	2,615
Net change in unrealized appreciation (depreciation) on investments			(556)	656
Ending Balance	$ 2,648	$ 3,271	$ 2,648	$ 3,271

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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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