Investments - Summary of Investments at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2022		Dec. 31, 2021
Summary Of Investment Holdings [Line Items]
Cost	$ 1,291,456	[1],[2],[3]	$ 1,244,846	[4],[5],[6]
Fair Value	1,262,956	[1],[2],[3]	1,270,366	[4],[5],[6]
Unrealized Appreciation/ (Depreciation)	(28,500)		25,520
Senior Secured First Lien
Summary Of Investment Holdings [Line Items]
Cost	312,345		335,207
Fair Value	301,001		329,795
Unrealized Appreciation/ (Depreciation)	(11,344)		(5,412)
Unitranche First Lien
Summary Of Investment Holdings [Line Items]
Cost	842,867		719,594
Fair Value	824,107		731,017
Unrealized Appreciation/ (Depreciation)	(18,760)		11,423
Unitranche First Lien Last Out
Summary Of Investment Holdings [Line Items]
Cost	14,879		15,698
Fair Value	13,827		13,723
Unrealized Appreciation/ (Depreciation)	(1,052)		(1,975)
Senior Secured Second Lien
Summary Of Investment Holdings [Line Items]
Cost	67,001		72,413
Fair Value	60,877		72,723
Unrealized Appreciation/ (Depreciation)	(6,124)		310
Unsecured Debt One
Summary Of Investment Holdings [Line Items]
Cost	4,984		5,577
Fair Value	4,533		5,620
Unrealized Appreciation/ (Depreciation)	(451)		43
Equity & Other
Summary Of Investment Holdings [Line Items]
Cost	35,993		37,611
Fair Value	44,851		59,528
Unrealized Appreciation/ (Depreciation)	8,858		21,917
LLC/LP Equity Interests
Summary Of Investment Holdings [Line Items]
Cost	13,387		58,746
Fair Value	13,760		57,960
Unrealized Appreciation/ (Depreciation)	$ 373		$ (786)

[1] All debt investments are income-producing, unless otherwise noted. Equity and member interests are non-income-producing unless otherwise noted. The Company generally acquires its investments in private transactions exempt from registration under the Securities Act of 1933 (the “1933 Act” or the "Securities Act"). Its investments are therefore generally subject to certain limitations on resale, and may be deemed to be “restricted securities” under the Securities Act.

[2] All positions held are non-controlled/non-affiliated investments, unless otherwise noted, as defined by the Investment Company Act of 1940 (the “1940 Act”). Non-controlled/non-affiliated investments are investments that are neither controlled nor affiliated.

[3] The fair value of the investment was determined using significant unobservable inputs unless otherwise noted, as defined by the 1940 Act. See Note 2 “Summary of Significant Accounting Policies”

[4] All debt investments are income-producing, unless otherwise noted. Equity and member interests are non-income-producing unless otherwise noted. The Company generally acquires its investments in private transactions exempt from registration under the Securities Act. Its investments are therefore generally subject to certain limitations on resale, and may be deemed to be “restricted securities” under the Securities Act.

[5] All positions held are non-controlled/non-affiliated investments, unless otherwise noted, as defined by the Investment Company Act of 1940 (“1940 Act”). Non-controlled/non-affiliated investments are investments that are neither controlled nor affiliated.

[6] The fair value of the investment was determined using significant unobservable inputs unless otherwise noted, as defined by the 1940 Act. See Note 2 “Summary of Significant Accounting Policies”.