Dividends and Distributions - Summary of Dividends Declarations and Distributions (Details) - USD ($) $ / shares in Units, $ in Thousands					3 Months Ended		6 Months Ended
	Mar. 03, 2023	Dec. 09, 2022	Mar. 04, 2022	Dec. 10, 2021	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Share-Based Payment Arrangement [Abstract]
Distribution to shareholders (in dollars per share)	$ 0.33	$ 0.33	$ 0.30	$ 0.30
Cash Distribution	$ 43,548	$ 47,245	$ 37,358	$ 38,291	$ 56,396	$ 51,260	$ 112,792	$ 102,268
DRIP shares issued (in shares)	0	0	29,928	837,158
DRIP Shares Value	$ 12,848	$ 9,151	$ 13,902	$ 12,717
DRIP shares purchase (in shares)	959,844	689,422	882,358
DRIP shares purchase, weighted average exercised price per share (in dollars per share)	$ 13.39	$ 13.27	$ 15.24
Proceeds from stock issued during period, amount, DRIP			$ 457