Investments - Summary of Geographic Composition of Investments at Fair Value (Details) $ in Thousands, $ in Thousands		Dec. 31, 2022 USD ($)		Dec. 31, 2021 USD ($)		Dec. 31, 2021 CAD ($)
Summary Of Investment Holdings [Line Items]
Fair Value		$ 1,262,956	[1],[2],[3]	$ 1,270,366	[4],[5],[6]
Percentage of Fair Value		100.00%		100.00%		100.00%
United States
Summary Of Investment Holdings [Line Items]
Fair Value		$ 1,111,350	[1],[2],[3]	$ 1,159,851	[4],[5],[6]
Percentage of Fair Value		88.10%		91.30%		91.30%
UNITED KINGDOM
Summary Of Investment Holdings [Line Items]
Fair Value		$ 58,591		$ 51,416	[4],[5],[6]
Percentage of Fair Value		4.60%		4.00%		4.00%
CANADA
Summary Of Investment Holdings [Line Items]
Fair Value		$ 31,890		$ 34,114		$ 34,114	[4],[5],[6]
Percentage of Fair Value		2.50%		2.70%		2.70%
Australia
Summary Of Investment Holdings [Line Items]
Fair Value	[1],[2],[3]	$ 19,490
Percentage of Fair Value		1.50%
Netherlands
Summary Of Investment Holdings [Line Items]
Fair Value		$ 15,352		$ 9,987	[4],[5],[6]
Percentage of Fair Value		1.20%		0.80%		0.80%
Belgium
Summary Of Investment Holdings [Line Items]
Fair Value		$ 14,166	[1],[2],[3]	$ 14,998	[4],[5],[6]
Percentage of Fair Value		1.10%		1.20%		1.20%
SWEDEN
Summary Of Investment Holdings [Line Items]
Fair Value	[1],[2],[3]	$ 12,117
Percentage of Fair Value		1.00%

[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”.