Agreements and Related Party Transactions - Additional Information (Details) - USD ($)			1 Months Ended	3 Months Ended
	Mar. 31, 2020	Apr. 15, 2011	Nov. 30, 2025	Mar. 31, 2026	Mar. 31, 2025
Related Party Transaction [Line Items]
Management fees				$ 12,593,000	$ 13,083,000
Administration Agreement
Related Party Transaction [Line Items]
Agreement termination period			60 days
Administration Agreement \| Adviser \| Other General and Administrative Expenses
Related Party Transaction [Line Items]
Expenses incurred				900,000	1,000,000
Investment Advisory Agreement
Related Party Transaction [Line Items]
Agreement termination period			60 days
Percentage of management fee on gross assets		1.50%
Management fees				12,600,000	13,100,000
Percentage of excess pre-incentive fee net investment income for immediate preceding calendar quarter		100.00%
Percentage of hurdle rate		1.50%
Percentage of total pre-Incentive fee net investment income payable quarterly		17.50%
Percentage of excess pre-Incentive Fee net investment income quarterly		1.82%
Percentage of all remaining pre-Incentive Fee net investment income quarterly		17.50%
Percentage of excess catch-up provision for pre-Incentive Fee net investment income		100.00%
Percentage of all pre-Incentive Fee net investment income		17.50%
Percentage of pre-Incentive Fee net investment income annualized		7.28%
Percentage of excess pre-Incentive Fee net investment income		17.50%
Percentage of pre-Incentive Fee net investment income payable in any quarter		1.82%
Percentage of weighted cumulative realized capital gains less cumulative realized capital losses and unrealized capital losses		15.00%
Incentive fees				8,500,000	7,800,000
Incentive fees realized and payable to advisor				8,500,000	11,500,000
Incentive fees accrued related to expense (reversal) of capital gains fees				0	(3,700,000)
Investment Advisory Agreement \| Capital Gains Accrue Following March 31, 2014
Related Party Transaction [Line Items]
Percentage of incentive fee rate		17.50%
Investment Advisory Agreement \| Realized Capital Gains Accrued Prior to March 31, 2014
Related Party Transaction [Line Items]
Percentage of incentive fee rate		15.00%
Investment Advisory Agreement \| Realized Capital Gains Accrued Beginning April 1, 2014
Related Party Transaction [Line Items]
Percentage of incentive fee rate		17.50%
Investment Advisory Agreement \| Future Realized Capital Gains Prior to April 1, 2014
Related Party Transaction [Line Items]
Remaining investments	$ 0
Incentive fee rate	17.50%
Investment Advisory Agreement \| Leverage Waiver
Related Party Transaction [Line Items]
Management fees				$ 300,000	$ 400,000
Percentage of asset coverage		200.00%
Percentage of management fee in excess of annual rate on gross assets		1.00%
Percentage of management fee in excess of quarter rate on gross assets		0.25%

Sixth Street Specialty Lending, Inc. 10-Q