Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Operating activities
Net income	$ 121,253	$ 109,065	$ 104,952
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	16,259	20,984	33,696
Amortization of FDIC indemnification asset	3,836	7,552	14,604
Net gain on sale of securities	(160)	(310)	(90)
Net gain on sale of loans	(8,053)	(6,694)	(5,539)
Net (gain) loss on FDIC indemnification asset	1,069	2,277	(4,506)
Net (gain) loss on sale of premises and equipment	1,974	(1,983)	3,280
Net loss from sale/writedowns of repossessed property	1,263	5,382	8,644
Provision for loan and lease losses	16,955	19,041	684
Provision for loan servicing rights loss	13	0	0
Stock-based compensation	3,517	1,236	0
Originations of residential real estate loans held-for-sale	(294,221)	(281,098)	(216,361)
Proceeds from sales of residential real estate loans held-for-sale	299,223	288,306	219,790
Net deferred income taxes	(1,563)	7,040	(12,463)
Changes in:
Accrued interest receivable	(1,337)	(1,468)	(1,544)
Other assets	6,222	(1,814)	(1,721)
FDIC clawback liability	1,061	917	1,153
Accrued interest payable and other liabilities	19,017	30,330	(441)
Net cash provided by operating activities	186,328	198,763	144,138
Investing activities
Purchase of securities available for sale	(278,291)	(353,249)	(222,711)
Proceeds from sales of securities available for sale	145,934	105,190	47,309
Proceeds from maturities of securities available for sale	306,514	269,284	307,090
Net increase in loans	(503,394)	(553,976)	(464,143)
(Payment) reimbursement of covered losses from FDIC indemnification claims	(960)	2,127	8,914
Purchase of premises and equipment	(15,456)	(3,895)	(4,978)
Proceeds from sale of premises and equipment	741	3,576	2,736
Proceeds from sale of repossessed property	12,173	35,942	32,700
Purchase of FHLB stock	(48,295)	(50,335)	(16,890)
Proceeds from redemption of FHLB stock	43,045	50,512	9,733
Business acquisitions, net of cash acquired	(15,669)	0	0
Net cash used in investing activities	(353,658)	(494,824)	(300,240)
Financing activities
Net increase in deposits	355,001	334,885	103,972
Net (decrease) increase in securities sold under agreements to repurchase	(149,238)	23,584	(55,875)
Net increase in FHLB advances and other borrowings	279,827	5,906	184,487
Proceeds from issuance of subordinated notes payable, net	0	34,632	0
Payment of related party notes payable	0	(41,295)	0
Common stock repurchased	0	(60,000)	0
Dividends paid	(31,419)	(20,520)	(102,000)
Net cash provided by financing activities	454,171	277,192	130,584
Net increase (decrease) in cash and cash equivalents	286,841	(18,869)	(25,518)
Cash and cash equivalents, beginning of year	237,770	256,639	282,157
Cash and cash equivalents, end of year	524,611	237,770	256,639
Supplemental disclosures of cash flows information
Cash payments for interest	33,456	31,150	33,570
Cash payments for income taxes	54,570	52,319	75,695
Supplemental schedules of noncash investing and financing activities
Loans transferred to repossessed assets	(4,331)	(7,636)	(33,502)
Repossessed property transferred to premises and equipment	$ (840)	$ 0	$ 0