Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net income	$ 36,903	$ 30,461
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization	5,365	4,103
Amortization of FDIC indemnification asset	867	1,032
Net loss on sale of securities	0	354
Gain on redemption of subordinated debentures	(111)	0
Net gain on sale of loans	(3,165)	(1,270)
Net loss on FDIC indemnification asset	211	477
Net loss (gain) on sale of premises and equipment	9	(8)
Net loss (gain) from sale/writedowns of repossessed property	658	(110)
Provision for loan and lease losses	7,049	3,889
Reversal of provision for loan servicing rights loss	(5)	0
Stock-based compensation	1,635	1,049
Originations of residential real estate loans held for sale	(87,868)	(59,716)
Proceeds from sales of residential real estate loans held for sale	94,866	59,446
Deferred income taxes	(817)	(344)
Changes in:
Accrued interest receivable	174	2,141
Other assets	(524)	4,770
FDIC clawback liability	267	238
Accrued interest payable, fair value of derivatives and other liabilities	(62,884)	(6,018)
Net cash (used in) provided by operating activities	(7,370)	40,494
Investing activities
Purchase of securities available for sale	(144,530)	(59,721)
Proceeds from maturities of securities available for sale	67,468	55,411
Net increase in loans	(105,771)	(204,582)
(Payment) reimbursement of covered losses from FDIC indemnification claims	(188)	28
Purchase of premises and equipment	(940)	(2,245)
Proceeds from sale of premises and equipment	1	597
Proceeds from sale of repossessed property	2,641	1,054
Purchase of FHLB stock	(3,000)	(5,606)
Proceeds from redemption of FHLB stock	9,512	9,090
Net cash used in investing activities	(174,807)	(205,974)
Financing activities
Net increase in deposits	101,663	275,553
Net increase in securities sold under agreements to repurchase	1,053	2,600
Proceeds from FHLB advances and other borrowings	74,999	75,000
Repayments on FHLB advances and other borrowings	(235,000)	(205,000)
Redemption of subordinated debentures	(5,000)	0
Dividends paid	(9,981)	(7,733)
Net cash (used in) provided by financing activities	(72,266)	140,420
Net decrease in cash and cash equivalents	(254,443)	(25,060)
Cash and cash equivalents, beginning of period	524,611	237,770
Cash and cash equivalents, end of period	270,168	212,710
Supplemental disclosure of cash flow information
Cash payments for interest	9,246	7,092
Cash payments for income taxes	10,574	2,792
Supplemental disclosure of noncash investing and financing activities
Loans transferred to repossessed properties	$ (1,110)	$ (555)