CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 79,509	$ 50,281
Other comprehensive income (loss) net of tax:
Net unrealized gain (loss) during the period on available-for-sale investment securities, net of tax of $1,659 and $3,864	(5,521)	(12,934)
Reclassification adjustment of net (gain) loss from sale of available-for-sale securities included in net income, net of tax of $0 and $(19)	0	62
Net unrealized gain (loss) from investment securities, net of reclassification adjustment	(5,521)	(12,872)
Net unrealized gain (loss) during the period on borrowings cash flow hedges, net of tax of $1,572 and $(1,483)	(5,234)	4,963
Net unrealized gain (loss) in cash flow hedging instruments, net of reclassification adjustment	(5,234)	4,963
Other comprehensive income (loss)	(10,755)	(7,909)
Comprehensive income	$ 68,754	$ 42,372