Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating activities
Net (loss) income	$ (697,344)	$ 90,297
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	8,373	5,916
Amortization of FDIC indemnification asset	641	853
Net loss on sale of securities and other assets	4,716	2,974
Net gain on sale of loans	(3,148)	(2,724)
Provision for loan and lease losses	79,898	12,888
Goodwill and intangible assets impairment	742,352	0
Provision for loan servicing rights loss	7	0
Stock-based compensation	1,637	1,839
Originations of residential real estate loans held for sale	(172,370)	(98,875)
Proceeds from sales of residential real estate loans held for sale	178,527	103,407
Net deferred income taxes	(48,238)	688
Changes in:
Accrued interest receivable	9,341	2,727
Other assets	(66,709)	22,116
Accrued interest payable and other liabilities	12,890	(27,768)
Net cash provided by operating activities	50,573	114,338
Investing activities
Purchase of securities available for sale	(413,887)	(541,872)
Proceeds from sales of securities available for sale	0	97,212
Proceeds from maturities of securities available for sale	234,077	94,926
Net increase in loans	(11,939)	(383,665)
(Payment) recovery of covered losses from FDIC indemnification claims	(43)	43
Purchase of premises and equipment	(3,861)	(5,953)
Proceeds from sale of premises and equipment	0	299
Proceeds from sale of repossessed property	12,368	6,593
Purchase of FHLB stock	(110,637)	(46,948)
Proceeds from redemption of FHLB stock	92,350	47,030
Net cash paid in business acquisition	(4,711)	0
Net cash used in investing activities	(206,283)	(732,335)
Financing activities
Net (decrease) increase in deposits	(121,163)	734,966
Net decrease in securities sold under agreements to repurchase and other short-term borrowings	(4,183)	(28,370)
Proceeds from FHLB advances and other long-term borrowings	650,000	465,000
Repayments on FHLB advances and other long-term borrowings	(190,000)	(465,000)
Common stock repurchased	(39,983)	(74,659)
Taxes paid related to net share settlement of equity awards	(1,295)	(1,227)
Dividends paid	(33,654)	(28,771)
Net cash provided by financing activities	259,722	601,939
Net increase (decrease) in cash and cash equivalents	104,012	(16,058)
Cash and cash equivalents, beginning of period	243,474	298,696
Cash and cash equivalents, end of period	347,486	282,638
Supplemental disclosure of cash flow information
Cash payments for interest	56,613	52,551
Cash payments for income taxes	17,194	19,113
Supplemental disclosure of noncash investing and financing activities
Loans transferred to repossessed properties	$ (7,507)	$ (17,919)