Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021		Sep. 30, 2020
Investment income
Total investment income	$ 387,802	$ 307,125		$ 298,953
Expenses
Interest and other debt financing expenses	89,378	65,739		74,858
Base management fee	73,866	61,858		59,243
Incentive fee	17,756	3,214		13,831
Professional fees	3,607	3,992		4,727
Administrative service fee	7,188	7,227		6,037
General and administrative expenses	1,720	1,423		1,198
Total expenses	193,515	143,453		159,894
Base management fee waived (Note 3)	(1,904)	(4,000)		0
Net expenses	191,611	139,453		159,894
Net investment income before taxes	196,191	167,672		139,059
Income tax	72	0		0
Net investment income after taxes	196,119	167,672		139,059
Net realized gain (loss) from:
Net realized (gain) loss on investments	19,549	13,324		(18,680)
Foreign currency transactions	(253)	(5,419)		20
Forward currency contracts	1,080	0		0
Net realized gain (loss) on investments and foreign currency transactions	20,376	7,905		(18,660)
Net change in unrealized appreciation (depreciation) from:
Debt and equity securities, unrealized gain (loss)	(56,806)	160,175		(61,850)
Translation of assets and liabilities in foreign currencies	(37,335)	3,917		(2,728)
Forward currency contracts	32,243	1,154		(949)
Net change in unrealized appreciation (depreciation) on investment transactions	(61,898)	165,246		(65,527)
Net gain (loss) on investment transactions	(41,522)	173,151		(84,187)
Provision for taxes on realized gain on investments	(302)	0		0
Provision for taxes on unrealized appreciation on investments	(855)	(543)		0
Net increase (decrease) in net assets resulting from operations	$ 153,440	$ 340,280		$ 54,872
Per Common Share Data
Diluted earnings per common share (in dollars per share)	$ 0.90	$ 2.03		$ 0.37
Basic earnings per common share (in dollars per share)	0.90	2.03		0.37
Dividends and distributions declared per common share (in dollars per share)	$ 1.20	$ 1.16		$ 1.37
Diluted weighted average common shares outstanding (in shares)	170,674,570	167,994,042		148,913,560
Basic weighted average common shares outstanding (in shares)	170,674,570	167,994,042		148,913,560
Non-controlled/non-affiliate company investments
Investment income
Interest income	$ 376,280	$ 295,421		$ 292,507
Dividend income	684	1,713		291
Fee income	4,232	4,962		1,760
Total investment income	381,196	302,096		294,558
Net realized gain (loss) from:
Net realized (gain) loss on investments	19,383	17,245		(52)
Net change in unrealized appreciation (depreciation) from:
Debt and equity securities, unrealized gain (loss)	(43,796)	145,131		(64,216)
Non-controlled affiliate company investments
Investment income
Interest income	6,498	5,029		2,576
Fee income	6	12		0
Total investment income	6,504	5,041		2,576
Net realized gain (loss) from:
Net realized (gain) loss on investments	166	(3,921)	[1]	(14,592)
Net change in unrealized appreciation (depreciation) from:
Debt and equity securities, unrealized gain (loss)	(6,886)	15,543		(622)
Controlled affiliate company investments
Investment income
Interest income	98	(12)		(86)
Dividend income	0	0		1,905
Fee income	4	0		0
Total investment income	102	(12)		1,819
Net realized gain (loss) from:
Net realized (gain) loss on investments	0	0	[2]	(4,036)
Net change in unrealized appreciation (depreciation) from:
Debt and equity securities, unrealized gain (loss)	$ (6,124)	$ (499)		$ 2,988

[1] Transactions related to investments in non-controlled affiliates for the year ended September 30, 2021 were as follows: Portfolio Company Fair value as of September 30, 2020 Gross Additions(a) Gross Reductions(b) Net change in unrealized gain (loss)Net realized gain (loss)Fair value as of September 30, 2021Interest, dividend and fee income Abita Brewing Co. LLC(c) $— $27,863 $(20,062)$2,249 $— $10,050 $931  Benetech, Inc. 2,672 410 (795)112 — 2,399 349  Dental Holdings Corporation 9,320 561 (13,657)1,792 1,984 — 462 Elite Dental Partners LLC15,368 668 (75)991 — 16,952 955 Paradigm DKD Group, LLC2,460 1,196 (1,215)186 — 2,627 19  Rubio's Restaurants, Inc(d) — 28,760 (16,470)11,008 (5,739)17,559 1,792  Sloan Company, Inc., The 4,365 637 (574)900 (166)5,162 67  Switchfly LLC 7,229 453 — (1,514)— 6,168 469  Uinta Brewing Company 586 266 (209)(181)— 462 (3) Total Non-Controlled Affiliates $42,000 $60,814 $(53,057)$15,543 $(3,921)$61,379 $5,041 

[2] Transactions related to investments in controlled affiliates for the year ended September 30, 2021 were as follows: Portfolio Company Fair value as of September 30, 2020 Gross Additions(a) Gross Reductions(b) Net change in unrealized gain (loss)Net realized gain (loss)Fair value as of September 30, 2021Interest, dividend and fee incomeMMan Acquisition Co.$18,736 $5,023 $(5,023)$(499)$— $18,237 $(12) Total Controlled Affiliates $18,736 $5,023 $(5,023)$(499)$— $18,237 $(12)