Summary of Significant Accounting Policies - Additional Information (Details)		1 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($)	Oct. 31, 2021 USD ($)	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) Loan shares	Dec. 31, 2021 USD ($) Loan shares	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Investment cost			$ 1,106,849,000	$ 1,150,602,000
Investment owned, fair value			$ 1,067,009,000	$ 1,126,309,000
PIK Income as a % of net investment income			12.20%	8.00%	4.20%
Payment of excise tax percentage			4.00%
Percentage of minimum beneficial ownership of voting securities for control			25.00%
Percentage of minimum board representation for control			50.00%
Percentage of beneficial ownership of voting securities for affiliation			5.00%
Potentially dilutive securities outstanding | shares			0	0	0
Other comprehensive income			$ 0	$ 0	$ 0
Mojix Inc
Summary Of Significant Accounting Policies [Line Items]
Number of loans | Loan					6
Cash Equivalents
Summary Of Significant Accounting Policies [Line Items]
Investments in money market funds			0	5,600,000
Second Private Offering
Summary Of Significant Accounting Policies [Line Items]
Offering cost excluding placement agent fees						$ 600,000
Placement agent fees						200,000
Offering cost						700,000
IPO
Summary Of Significant Accounting Policies [Line Items]
Offering cost		$ 7,000,000
Maximum | Second Private Offering
Summary Of Significant Accounting Policies [Line Items]
Offering cost						$ 600,000
Maximum | Initial Private Offering
Summary Of Significant Accounting Policies [Line Items]
Adjustment to additional paid in capital stock issued issuance costs	$ 1,000,000
Minimum | Initial Private Offering | Runway Growth Holdings LLC
Summary Of Significant Accounting Policies [Line Items]
Adjustment to additional paid in capital stock issued issuance costs	$ 1,000,000
Pivot3, Inc.
Summary Of Significant Accounting Policies [Line Items]
Write off accrued interest			0	$ 0
Number of loans | Loan				1	1
Aggregate principal funded on non-accrual status				$ 19,200,000	$ 30,300,000
Fair value on non-accrual status				$ 9,300,000	$ 28,300,000
Percentage of investment portfolio on non-accrual status				0.80%	3.90%
Cumulative interest on investments				$ 3,900,000	$ 4,800,000
Pivot3, Inc. | Senior Secured Term Loan
Summary Of Significant Accounting Policies [Line Items]
Investment cost			18,000,000
Investment owned, fair value			950,000
Realized loss			$ 17,000,000
Pivot3, Inc. | Cash Interest Income
Summary Of Significant Accounting Policies [Line Items]
Cumulative interest on investments				3,600,000	4,100,000
Pivot3, Inc. | OID Accretion Interest Income
Summary Of Significant Accounting Policies [Line Items]
Cumulative interest on investments				$ 300,000	$ 700,000