Financial Highlights (Details) - USD ($)			1 Months Ended			12 Months Ended
	Jul. 14, 2022	Feb. 07, 2020	Aug. 31, 2021	Dec. 21, 2019	May 29, 2015	Feb. 28, 2023
Investment Company, Financial Highlights [Abstract]
Indebtedness amount						$ 1,000
Revolving credit facility, description						The Revolving Credit Facility, SBA Debentures, 7.00% Notes Payable 2025, 4.375% Notes Payable 2026, 4.35% Notes Payable 2026, 7.75% Notes Payable 2025 and 6.25% Notes Payable 2027 are not registered for public trading.
Debt instrument redemption, description	On July 14, 2022, the Company redeemed $43.1 million in aggregate principal amount of the $43.1 million in aggregate principal amount of issued and outstanding 7.25% 2025 Notes and are no longer listed on the NYSE.	On December 21, 2019 and February 7, 2020, the Company redeemed $50.0 million and $24.5 million, respectively, in aggregate principal amount of the $74.5 million in aggregate principal amount of issued and outstanding 2023 Notes and are no longer listed on the NYSE.	On August 31, 2021, the Company redeemed $60.0 million in aggregate principal amount of the issued and outstanding 6.25% 2025 Notes and, as a result of the full redemption, the 6.25% 2025 Notes are no longer listed on the NYSE.	On December 21, 2019 and February 7, 2020, the Company redeemed $50.0 million and $24.5 million, respectively, in aggregate principal amount of the $74.5 million in aggregate principal amount of issued and outstanding 2023 Notes and are no longer listed on the NYSE.	On May 29, 2015, the Company entered into a Debt Distribution Agreement with Ladenburg Thalmann & Co. through which the Company may offer for sale, from time to time, up to $20.0 million in aggregate principal amount of the 2020 Notes through an At-the-Market (“ATM”) offering. Prior to the 2020 Notes being redeemed in full, the Company had sold 539,725 units of the 2022 Notes with a principal of $13.5 million at an average price of $25.31 for aggregate net proceeds of $13.4 million (net of transaction costs).