Shareholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Feb. 08, 2021	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Class of Stock [Line Items]
Dividend rate	4.875%
Proceeds from issuance of preferred stock, net	$ 293,325	$ 0	$ 0	$ 293,325
Stock repurchased (in shares)		1,165,161	92,774
Additional shares authorized to be repurchased (in shares)		2,559,183
Weighted average
Class of Stock [Line Items]
Weighted average cost of repurchased stock (in dollars per share)		$ 26.14	$ 35.14
Public Offering
Class of Stock [Line Items]
Number of shares issued in transaction (in shares)	12,000,000
Public offering price (in usd per share)	$ 25.00
Public Offering | Series A Preferred Stock
Class of Stock [Line Items]
Number of shares issued in transaction (in shares)	300,000