Fair Value Measurements (Details) - Schedule of Quantitative Information About Level 3 Fair Value Measurements Of Our Investments - Level 3 [Member] - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Jun. 30, 2023	Sep. 30, 2022
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 162,255	$ 146,675
Senior Secured First Lien Term Loans [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 74,666	$ 65,428
Valuation Methodology	Market Approach	Income Approach
Unobservable Input	Market Yield	Market Yield
Range (Weighted Average)	8.50% - 32.0% (13.4%)	8.50% - 24.00% (10.57%)
Senior Secured First Lien Term Loans One [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 764	$ 3,807
Valuation Methodology	Market Approach	Market Approach
Unobservable Input	Revenue Multiple	EBITDA Multiple
Range (Weighted Average)	0.3x - 0.3x (0.3x)	4.0x - 5.0x (4.5x)
Senior Secured First Lien Term Loans Two [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 9,830	$ 4,152
Valuation Methodology	Market Approach	Market Approach
Unobservable Input	EBITDA Multiple	Revenue Multiple
Range (Weighted Average)	1.7x - 5.0x (3.1x)	0.2x - 0.3x (2.5x)
Senior Secured First Lien Term Loans Three [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 865	$ 865
Valuation Methodology	Market Approach	Income Approach
Unobservable Input	LTM EBITDA Multiple	Market Spread
Range (Weighted Average)	5.75x - 6.75x (6.25x)	5.75% - 6.25% (6.00%)
Senior Secured Notes [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value
Valuation Methodology	Market Approach (Guideline Comparable)
Unobservable Input	EBITDA Multiple
Range (Weighted Average)	21.0x - 22.0x (21.5x)
Unsecured Debt [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 161
Valuation Methodology	Cost Approach
Unobservable Input	Transaction
Range (Weighted Average)	N/A
Equity/Warrants [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 34,125	$ 47,138
Valuation Methodology	Cost Approach	Cost Approach
Unobservable Input	Replacement Cost	Replacement Cost
Range (Weighted Average)	N/A
Equity/Warrants One [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 12,278	$ 11,444
Valuation Methodology	Income Approach	Market Approach
Unobservable Input	Market Yield	EBITDA Multiple
Range (Weighted Average)	11.5% - 13.0% (5.3%)	2.0x - 21.0x (17.4x)
Equity/Warrants Two [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 11,674	$ 9,951
Valuation Methodology	Market Approach	Income Approach
Unobservable Input	LTM Multiple	Market Yield
Range (Weighted Average)	5.8x - 6.8x (6.3x)	8.50% - 13.25% (12.75%)
Equity/Warrants Three [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 9,422	$ 1,283
Valuation Methodology	Market Approach	Market Approach
Unobservable Input	EBITDA Multiple	Sum of the Parts/Estimated Proceeds
Range (Weighted Average)	1.8x - 38.6x (5.9x)	8.1x - 11.4x (9.8x)
Equity/Warrants Four [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 8,000
Valuation Methodology	Recent Purchase
Unobservable Input	Purchase Price
Range (Weighted Average)	N/A - N/A (N/A)
Equity/Warrants Five [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 65
Valuation Methodology	Market Approach
Unobservable Input	Sum of the Parts/Estimated proceeds
Range (Weighted Average)	3.9x – 4.1x (4.0x)
Equity/Warrants Six [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 405
Valuation Methodology	Income Approach
Unobservable Input	DLOM (Discount for lack of Marketability)
Range (Weighted Average)	3.0x - 3.2x (3.1x)
Senior Secured First Lien Term Loans Four [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value		$ 2,607
Valuation Methodology		Market Approach
Unobservable Input		EBITDA Multiple
Range (Weighted Average)		9.0x - 10.0x (9.5x)