Consolidated Statements of Operations - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Investment income
Payment-in-kind interest income		$ 40,590	$ 23,354	$ 13,931
Total investment income		603,090	387,802	307,125
Expenses
Interest and other debt financing expenses		150,610	89,378	65,739
Base management fee		70,802	73,866	61,858
Incentive fee		74,066	17,756	3,214
Professional fees		5,041	3,607	3,992
Administrative service fee		8,300	7,188	7,227
General and administrative expenses		1,501	1,720	1,423
Total expenses		310,320	193,515	143,453
Base management fee waived (Note 3)		0	(1,904)	(4,000)
Net expenses		310,320	191,611	139,453
Net investment income - before tax		292,770	196,191	167,672
Excise tax		3,682	0	0
Income tax		0	72	0
Net investment income - after tax		289,088	196,119	167,672
Net realized gain (loss) from:
Net realized (gain) loss on investments		(46,496)	18,925	13,006
Foreign currency transactions		(328)	371	(5,101)
Forward currency contracts		2,711	1,080	0
Net realized gain (loss) on investment transactions		(44,113)	20,376	7,905
Net change in unrealized appreciation (depreciation) from:
Debt and equity securities, unrealized gain (loss)		14,267	(56,806)	161,867
Translation of assets and liabilities in foreign currencies		16,680	(37,335)	2,225
Forward currency contracts		(17,392)	32,243	1,154
Net change in unrealized appreciation (depreciation) on investment transactions		13,555	(61,898)	165,246
Net gain (loss) on investment transactions		(30,558)	(41,522)	173,151
(Provision) benefit for taxes on realized gains on investments		(207)	(302)	0
(Provision) benefit for taxes on unrealized appreciation on investments		308	(855)	(543)
Net increase (decrease) in net assets resulting from operations		$ 258,631	$ 153,440	$ 340,280
Per Common Share Data
Basic earnings per common share (in dollars per share)		$ 1.52	$ 0.90	$ 2.03
Diluted earnings per common share (in dollars per share)		1.52	0.90	2.03
Dividends and distributions declared per common share (in dollars per share)		$ 1.40	$ 1.20	$ 1.16
Basic weighted average common shares outstanding (in shares)		170,324,784	170,674,570	167,994,042
Diluted weighted average common shares outstanding (in shares)		170,324,784	170,674,570	167,994,042
Non-controlled/non-affiliate company investments
Investment income
Interest income		$ 542,780	$ 355,358	$ 282,500
Payment-in-kind interest income		36,662	20,922	12,921
Dividend income		16,241	684	1,713
Fee income		2,124	4,232	4,962
Total investment income		597,807	381,196	302,096
Net realized gain (loss) from:
Net realized (gain) loss on investments		(45,889)	18,759	16,927
Net change in unrealized appreciation (depreciation) from:
Debt and equity securities, unrealized gain (loss)		33,464	(43,796)	146,823
Non-controlled affiliate company investments
Investment income
Interest income		1,356	4,275	4,144
Payment-in-kind interest income		3,544	2,223	885
Fee income		76	6	12
Total investment income		4,976	6,504	5,041
Net realized gain (loss) from:
Net realized (gain) loss on investments		320	166	(3,921)
Net change in unrealized appreciation (depreciation) from:
Debt and equity securities, unrealized gain (loss)		(18,578)	(6,886)	15,543
Controlled affiliate company investments
Investment income
Interest income	[1]	(94)	(111)	(137)
Payment-in-kind interest income		384	209	125
Fee income		17	4	0
Gross Investment Income, Operating, Net Of Amortization		307	102	(12)
Net realized gain (loss) from:
Net realized (gain) loss on investments		(927)	0	0
Net change in unrealized appreciation (depreciation) from:
Debt and equity securities, unrealized gain (loss)		$ (619)	$ (6,124)	$ (499)

[1] Negative interest income amounts are due to amortization of the GCIC acquisition purchase premium. Refer to Note 2 for additional details on the GCIC acquisition purchase premium.