Dividends and Distributions - Summary of Dividends Declarations and Distributions (Details) - USD ($) $ / shares in Units, $ in Thousands							3 Months Ended		9 Months Ended
	Jun. 02, 2023	Mar. 03, 2023	Dec. 09, 2022	Jun. 03, 2022	Mar. 04, 2022	Dec. 10, 2021	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-Based Payment Arrangement [Abstract]
Distribution to shareholders (in dollars per share)	$ 0.33	$ 0.33	$ 0.33	$ 0.30	$ 0.30	$ 0.30
Cash Distribution	$ 44,518	$ 43,548	$ 47,245	$ 39,336	$ 37,358	$ 38,291	$ 56,066	$ 51,269	$ 168,858	$ 153,537
DRIP shares issued (in shares)	0	0	0	0	29,928	837,158
DRIP Shares Value	$ 11,548	$ 12,848	$ 9,151	$ 11,933	$ 13,902	$ 12,717
DRIP shares purchase (in shares)	854,808	959,844	689,422	917,845	882,358
DRIP shares purchase, weighted average exercised price per share (in dollars per share)	$ 13.51	$ 13.39	$ 13.27	$ 13.00	$ 15.24
Proceeds from stock issued during period, amount, DRIP					$ 457