Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 22,897	$ 22,372	$ 71,834	$ 77,538
Other comprehensive income (loss), net of tax:
Changes in unrealized gains (losses) on AFS securities, net of taxes of $(1,317), $437, $(3,432) and $1,756	4,102	(1,366)	10,690	(4,430)
Changes in unrealized gains (losses) on cash flow hedges, net of taxes of $3,601, $9, $8,847 and $(1,858)	(11,218)	(30)	(27,562)	4,608
Comprehensive income	$ 15,781	$ 20,976	$ 54,962	$ 77,716