Great Western Bancorp (GWB) 10-Q 30 Apr 20 2020 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Mar. 31, 2020	Apr. 27, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	001-36688
Entity Registrant Name	Great Western Bancorp, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-1308512
Entity Address, Address Line One	225 South Main Avenue
Entity Address, City or Town	Sioux Falls,
Entity Address, State or Province	SD
Entity Address, Postal Zip Code	57104
City Area Code	605
Local Phone Number	334-2548
Title of 12(b) Security	Common Stock, $0.01 par value per share
Trading Symbol	GWB
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (shares)		55,013,928
Document Fiscal Year Focus	2020
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	Q2
Amendment Flag	false
Entity Central Index Key	0001613665
Current Fiscal Year End Date	--09-30

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Assets
Cash and due from banks	$ 171,219	$ 201,487
Interest-bearing bank deposits	176,267	41,987
Cash and cash equivalents	347,486	243,474
Securities available for sale	1,990,027	1,783,208
Loans, net of unearned discounts and deferred fees, including $29,691 and $31,891 of loans covered by a FDIC loss share agreement at March 31, 2020 and September 30, 2019, respectively; $792,117 and $812,991 of loans at fair value under the fair value option at March 31, 2020 and September 30, 2019, respectively; and $4,342 and $7,351 of loans held for sale at March 31, 2020 and September 30, 2019, respectively	9,693,295	9,706,763
Allowance for loan and lease losses	(135,950)	(70,774)
Net loans	9,557,345	9,635,989
Premises and equipment, including $706 and $2,757 of property held for sale at March 31, 2020 and September 30, 2019, respectively	120,653	120,645
Accrued interest receivable	49,358	58,699
Other repossessed property, including $0 of property covered by a FDIC loss share agreement at both March 31, 2020 and September 30, 2019	27,289	36,764
Goodwill	0	739,023
Cash surrender value of life insurance policies	31,231	30,796
Net deferred tax assets	48,084	7,286
Other assets	216,335	132,417
Total assets	12,387,808	12,788,301
Deposits
Noninterest-bearing	1,973,629	1,956,025
Interest-bearing	8,205,486	8,344,314
Total deposits	10,179,115	10,300,339
Securities sold under agreements to repurchase	64,809	68,992
FHLB advances and other borrowings	800,000	340,000
Subordinated debentures and subordinated notes payable	108,740	108,636
Accrued expenses and other liabilities	81,680	70,085
Total liabilities	11,234,344	10,888,052
Stockholders’ equity
Common stock, $0.01 par value, authorized 500,000,000 shares; 55,013,928 shares issued and outstanding at March 31, 2020 and 56,283,659 shares issued and outstanding at September 30, 2019	550	563
Additional paid-in capital	1,190,381	1,228,714
Retained earnings	(73,705)	657,475
Accumulated other comprehensive income	36,238	13,497
Total stockholders' equity	1,153,464	1,900,249
Total liabilities and stockholders' equity	$ 12,387,808	$ 12,788,301

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Assets
Loans covered by a FDIC loss sharing agreement	$ 29,691	$ 31,891
Loans and written loan commitments at fair value under the fair value option	792,117	812,991
Loan held for sale	4,342	7,351
Property held for sale	706	2,757
Property covered by FDIC loss share arrangements	$ 0	$ 0
Stockholders’ equity
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	55,013,928	56,283,659
Common stock, shares outstanding (in shares)	55,013,928	56,283,659

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Interest income
Loans	$ 113,356	$ 123,432	$ 232,787	$ 245,763
Investment securities	11,329	9,957	22,827	19,145
Federal funds sold and other	558	497	1,166	1,039
Total interest income	125,243	133,886	256,780	265,947
Interest expense
Deposits	18,867	27,098	40,807	50,892
FHLB advances and other borrowings	3,155	1,923	6,268	3,926
Subordinated debentures and subordinated notes payable	1,238	1,390	2,549	2,760
Total interest expense	23,260	30,411	49,624	57,578
Net interest income	101,983	103,475	207,156	208,369
Provision for loan and lease losses	71,795	7,673	79,898	12,888
Net interest income after provision for loan and lease losses	30,188	95,802	127,258	195,481
Noninterest income
Service charges and other fees	9,188	10,209	20,597	21,897
Wealth management fees	3,122	2,117	6,086	4,358
Mortgage banking income, net	1,145	991	2,757	2,311
Net loss on sale of securities	0	0	0	(513)
Net increase in fair value of loans at fair value	35,541	14,018	20,608	33,234
Net realized and unrealized loss on derivatives	(50,214)	(11,032)	(36,698)	(29,348)
Other	1,135	1,920	2,300	3,004
Total noninterest (loss) income	(83)	18,223	15,650	34,943
Noninterest expense
Salaries and employee benefits	37,312	34,537	73,217	69,307
Data processing and communication	6,123	5,964	11,896	11,242
Occupancy and equipment	5,597	5,539	10,690	10,665
Professional fees	5,263	3,970	9,027	7,258
Advertising	958	1,216	1,823	2,154
Net loss on repossessed property and other related expenses	5,691	404	6,033	3,467
Goodwill and intangible assets impairment	742,352	0	742,352	0
Other	5,157	4,950	10,345	9,593
Total noninterest expense	808,453	56,580	865,383	113,686
(Loss) income before income taxes	(778,348)	57,445	(722,475)	116,738
(Benefit from) provision for income taxes	(37,730)	12,934	(25,131)	26,441
Net (loss) income	$ (740,618)	$ 44,511	$ (697,344)	$ 90,297
Basic earnings per common share
Weighted average shares outstanding (in shares)	55,906,002	56,994,817	56,141,816	57,484,838
Earnings per share (in dollars per share)	$ (13.25)	$ 0.78	$ (12.42)	$ 1.57
Diluted earnings per common share
Weighted average shares outstanding (in shares)	55,906,002	57,074,674	56,141,816	57,556,984
Diluted earnings per share (in dollars per share)	$ (13.25)	$ 0.78	$ (12.42)	$ 1.57
Dividends per share
Dividends paid	$ 16,769	$ 14,235	$ 33,654	$ 28,771
Dividends per share (in dollars per share)	$ 0.30	$ 0.25	$ 0.60	$ 0.50

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (740,618)	$ 44,511	$ (697,344)	$ 90,297
Securities available for sale:
Net unrealized holding gain arising during the period	38,341	11,523	30,181	30,192
Reclassification adjustment for net loss realized in net income	0	0	0	513
Income tax expense	(9,450)	(2,839)	(7,440)	(7,568)
Net change in unrealized gain on securities available for sale	28,891	8,684	22,741	23,137
Comprehensive (loss) income	$ (711,727)	$ 53,195	$ (674,603)	$ 113,434

Consolidated Statement of Stock

Consolidated Statement of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock Par Value	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income
Beginning balance at Sep. 30, 2018	$ 1,840,551	$ 589	$ 1,318,457	$ 553,014	$ (31,509)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	90,297			90,297
Other comprehensive income (loss), net of tax	23,137				23,137
Comprehensive (loss) income	113,434
Stock-based compensation, net of tax	1,839	1	1,838
Repurchase common stock	(74,659)	(21)	(74,638)
Common stock cash dividends	(28,771)			(28,771)
Ending balance at Mar. 31, 2019	1,852,394	569	1,245,657	614,540	(8,372)
Beginning balance at Dec. 31, 2018	1,812,008	568	1,244,232	584,264	(17,056)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	44,511			44,511
Other comprehensive income (loss), net of tax	8,684				8,684
Comprehensive (loss) income	53,195
Stock-based compensation, net of tax	1,426	1	1,425
Common stock cash dividends	(14,235)			(14,235)
Ending balance at Mar. 31, 2019	1,852,394	569	1,245,657	614,540	(8,372)
Beginning balance at Sep. 30, 2019	1,900,249	563	1,228,714	657,475	13,497
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(697,344)			(697,344)
Other comprehensive income (loss), net of tax	22,741				22,741
Comprehensive (loss) income	(674,603)
Stock-based compensation, net of tax	1,637	1	1,636
Repurchase common stock	(39,983)	(14)	(39,969)
Common stock cash dividends	(33,654)			(33,654)
Ending balance at Mar. 31, 2020	1,153,464	550	1,190,381	(73,705)	36,238
Beginning balance at Dec. 31, 2019	1,920,669	563	1,229,077	683,682	7,347
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(740,618)			(740,618)
Other comprehensive income (loss), net of tax	28,891				28,891
Comprehensive (loss) income	(711,727)
Stock-based compensation, net of tax	1,274	1	1,273
Repurchase common stock	(39,983)	(14)	(39,969)
Common stock cash dividends	(16,769)			(16,769)
Ending balance at Mar. 31, 2020	$ 1,153,464	$ 550	$ 1,190,381	$ (73,705)	$ 36,238

Consolidated Statement of Sto_2

Consolidated Statement of Stockholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Statement of Stockholders' Equity [Abstract]
Cash dividends paid on common stock (in dollars per share)	$ 0.30	$ 0.25	$ 0.60	$ 0.50

Consolidated Statements of Cash

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)

Nature of Operations and Summar

Nature of Operations and Summary of Significant Policies	6 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Nature of Operations and Summary of Significant Policies	Nature of Operations and Summary of Significant Policies Nature of Operations The Company is a bank holding company organized under the laws of Delaware and is listed on the NYSE under the symbol "GWB". The primary business of the Company is ownership of its wholly-owned subsidiary, Great Western Bank. The Bank is a full-service regional bank focused on relationship-based business and agri-business banking in Arizona, Colorado, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota and South Dakota. The Company and the Bank are subject to the regulation of certain federal and/or state agencies and undergo periodic examinations by those regulatory authorities. Substantially all of the Company’s income is generated from banking operations. Basis of Presentation The accompanying unaudited consolidated interim financial statements have been prepared in accordance with U.S. GAAP and reflect all adjustments that are, in the opinion of management, necessary for the fair presentation of the financial position and results of operations for the periods presented. All such adjustments are of a normal recurring nature. Certain previously reported amounts have been reclassified to conform to the current presentation. The unaudited interim consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements for the year ended September 30, 2019, which includes a description of significant accounting policies. The results of operations for interim periods are not necessarily indicative of the results that may be expected for the year or any other period. The accompanying unaudited consolidated financial statements include the accounts and results of operations of the Company and its subsidiaries after elimination of all significant intercompany accounts and transactions. The preparation of unaudited consolidated financial statements in conformity with U.S. GAAP requires management to make certain estimates and assumptions that affect the amounts reported on the consolidated financial statements and accompanying notes. Actual results could differ from these estimates. Changes in Significant Accounting Policies Pursuant to the Company's adoption of ASU 2016-02 and subsequent related ASUs as of October 1, 2019, the Company updated its accounting policy related to leases. See Note 12 for new disclosures and policy information related to the Company's leases. There were no other significant changes to the Company's accounting policies from those disclosed in the Company's Annual Report on Form 10-K for the fiscal year ended September 30, 2019 that could have a material effect on the Company's consolidated financial statements. Subsequent Events The Company has evaluated all events or transactions that occurred through the date the Company issued these financial statements. Other than those described below, there were no material events or transactions that would require recognition in the consolidated financial statements or disclosure in the notes to the consolidated financial statements. In April 2020, the Company offered loans to customers that are guaranteed by the SBA under its PPP authorized under the CARES Act. The Company has provided approximately $600.0 million in loans to customers under this program. The Bank also received approval from the FRB to access the PPP Liquidity Facility to fund PPP loans if needed. On April 30, 2020, the Board of Directors of the Company declared a dividend of $0.15 per common share payable on May 29, 2020 to stockholders of record as of close of business on May 15, 2020. With the many uncertainties of the COVID-19 pandemic, including the full impacts on the future financial results and operations of the Company, the Board of Directors determined a reduction to its regular quarterly dividend will help strengthen the Company's balance sheet and liquidity in light of the uncertainty surrounding the COVID-19 pandemic.

New Accounting Standards

New Accounting Standards	6 Months Ended
	Mar. 31, 2020
Accounting Changes and Error Corrections [Abstract]
New Accounting Standards	New Accounting Standards Accounting Standards Adopted in Fiscal Year 2020 In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities , which amended the hedge accounting recognition and presentation requirements in ASC 815 to improve the transparency and understandability of information conveyed to financial statement users about an entity’s risk management activities to better align the entity’s financial reporting for hedging relationships with those risk management activities and to reduce the complexity of and simplify the application of hedge accounting. ASU 2017-12 was effective for the Company on October 1, 2019. For the periods presented, the Company did not designate any derivative financial instruments as formal hedging relationships, and therefore, did not utilize hedge accounting. As such, ASU 2017-12 did not impact the Company's consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which requires that lessees recognize the assets and liabilities arising from leases on the balance sheet and disclose key information about leasing arrangements. Lessees are required to recognize an obligation for future lease payments measured on a discounted basis and a related right-of-use asset. ASU 2016-02 does not significantly change lease accounting requirements applicable to lessors; however, certain changes were made to align, where necessary, lessor accounting with the lessee accounting model and ASC Topic 606, Revenue from Contracts with Customers . In July 2018, the FASB issued ASU 2018-10, Codification Improvements to Topic 842, Leases , and ASU 2018-11, Leases (Topic 842), Targeted Improvements , which made technical corrections and improvements to the previous ASU issued, including a modified retrospective transition method that allows entities to apply the standard as of the adoption date. In December 2018, the FASB issued ASU 2018-20, Leases (Topic 842): Narrow-Scope Improvements for Lessors , which allowed lessors to exclude sales tax from consideration of the contract through a policy election and clarified treatment of certain lessor costs and variable payments for contracts with lease and nonlease components. The Company adopted this guidance beginning October 1, 2019 using the modified retrospective transition method and all practical expedients available other than the use of hindsight with respect to determining the lease term and assessing impairment of its right-of-use assets. As of the date of adoption, the Company's right-of-use assets and lease liabilities recorded in other assets and accrued expenses and other liabilities on the consolidated balance sheets were $19.9 million and $20.9 million, respectively, arising from operating leases in which the Company is the lessee. The Company also recognized a cumulative effect adjustment of $0.2 million as a result of remeasuring a pre-existing lease impairment as of the date of adoption. These ASUs did not have a material impact on the timing of expense or income recognition in the Company's consolidated statements of income. Accounting Standards Not Yet Adopted in Fiscal Year 2020 In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes in the Disclosure Requirements for Fair Value Measurement , which eliminates, adds and modifies certain disclosure requirements for fair value measurements. Among the changes, entities will no longer be required to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, but will be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. ASU 2018-13 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. Entities are also allowed to elect to early adopt the eliminated or modified disclosure requirements and delay adoption of the new disclosure requirements until after their effective date. As ASU 2018-13 only revises disclosure requirements, the Company does not believe this ASU will have a material impact on the consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which addresses timelier recording of credit losses on loans and other financial instruments held by financial institutions and other organizations. ASU 2016-13 requires institutions to measure all expected credit losses related to financial assets measured at amortized costs with an expected loss model based on historical experience, current conditions and reasonable and supportable forecasts relevant to affect the collectability of the financial assets, which is referred to as the current expected credit loss model. ASU 2016-13 requires enhanced disclosures, including qualitative and quantitative requirements, to help understand significant estimates and judgments used in estimating credit losses, as well as provide additional information about the amounts recorded in the financial statements. From November 2018 through February 2020, the FASB issued ASUs which made technical corrections and improvements to the previous ASU issued (ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments, Credit Losses; ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments - Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments; ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments - Credit Losses; and ASU 2020-02, Financial Instruments - Credit Losses (Topic 326) and Leases (Topic 842 )). The ASUs require the use of the modified retrospective approach for adoption. These ASUs will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted after December 15, 2018. The Company continues to make progress on its implementation plan including continuing to work through finalizing processes, controls and an independent model validation and we are on track to adopt as required on October 1, 2020. The Company is currently evaluating the potential impact on the consolidated financial statements; however, since the magnitude of the anticipated change in the allowance for credit losses will be impacted by economic conditions and trends in the Company’s portfolio at the time of adoption, the quantitative impact cannot yet be reasonably estimated. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , which aims to simplify the accounting for income taxes by removing certain exceptions to the general principles and also simplification of areas such as franchise taxes, step-up in tax basis goodwill, separate entity financial statements and interim recognition of enactment of tax laws or rate changes. The ASU will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020, with early adoption permitted. The Company is currently evaluating the potential impact of ASU 2019-12 on the consolidated financial statements. In January 2020, the FASB issued ASU 2020-01, Investments - Equity Securities (Topic 321), Investments - Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815): Clarifying the Interactions between Topic 321, Topic 323 and Topic 815 , which clarifies that an entity should consider observable transactions that require it to either apply or discontinue the equity method of accounting for the purposes of applying the fair value measurement alternative. The ASU will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020, with early adoption permitted. The Company does not expect adoption to have a material impact on the consolidated financial statements. In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting , which provides optional expedients and exceptions for a limited time period to ease the potential burden in accounting for reference rate reform on financial reporting. The amendments in ASU 2020-04 are elective for entities with contracts, including derivative contracts, that reference LIBOR or some other reference rate that are expected to be discontinued. For the Company's cash flow hedges, ASU 2020-04 allows: (i) an entity to change the reference rate without having to designate the hedging relationship; (ii) for cash flow hedges in which the designated hedged risk is LIBOR, allows an entity to assert that it remains probable that the hedged forecasted transaction will occur; and (iii) allows an entity to change the designated method used to assess hedge effectiveness and simplifies or temporarily suspends the assessment of hedge effectiveness for hedging relationships. ASU 2020-04 must be applied prospectively and was effective immediately upon issuance and remains effective through December 31, 2022. The Company is currently evaluating the impact that adopting this new accounting standard will have on the consolidated financial statements.

Securities Available for Sale

Securities Available for Sale	6 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Securities Available for Sale	Securities Available for Sale The amortized cost and approximate fair value of investments in securities, all of which are classified as available for sale according to management’s intent, are summarized as follows. Amortized Gross Unrealized Gains Gross Unrealized Losses Estimated (dollars in thousands) As of March 31, 2020 U.S. Treasury securities $ 69,629 $ 954 $ — $ 70,583 Mortgage-backed securities: Government National Mortgage Association 566,747 11,340 (733) 577,354 Federal Home Loan Mortgage Corporation 556,535 15,747 (731) 571,551 Federal National Mortgage Association 386,996 15,337 (27) 402,306 Small Business Assistance Program 300,498 5,725 (42) 306,181 States and political subdivision securities 60,511 517 (27) 61,001 Other 1,006 45 — 1,051 Total $ 1,941,922 $ 49,665 $ (1,560) $ 1,990,027 Amortized Gross Unrealized Gains Gross Unrealized Losses Estimated (dollars in thousands) As of September 30, 2019 U.S. Treasury securities $ 94,178 $ 599 $ (32) $ 94,745 Mortgage-backed securities: Government National Mortgage Association 501,139 3,374 (3,027) 501,486 Federal Home Loan Mortgage Corporation 463,974 8,840 (770) 472,044 Federal National Mortgage Association 322,340 5,409 (398) 327,351 Small Business Assistance Program 316,502 3,674 (154) 320,022 States and political subdivision securities 66,145 494 (116) 66,523 Other 1,006 31 — 1,037 Total $ 1,765,284 $ 22,421 $ (4,497) $ 1,783,208 The amortized cost and approximate fair value of debt securities available for sale as of March 31, 2020 and September 30, 2019, by contractual maturity, are shown below. Maturities of mortgage-backed securities may differ from contractual maturities because the mortgages underlying the securities may be called or repaid without penalty. March 31, 2020 September 30, 2019 Amortized Estimated Amortized Estimated (dollars in thousands) Due in one year or less $ 82,615 $ 83,577 $ 58,377 $ 58,343 Due after one year through five years 35,858 36,102 89,836 90,601 Due after five years through ten years 11,667 11,905 12,110 12,324 Due after ten years — — — — 130,140 131,584 160,323 161,268 Mortgage-backed securities 1,810,776 1,857,392 1,603,955 1,620,903 Securities without contractual maturities 1,006 1,051 1,006 1,037 Total $ 1,941,922 $ 1,990,027 $ 1,765,284 $ 1,783,208 Proceeds from sales of securities available for sale were $0.0 million for both the three and six months ended March 31, 2020. Proceeds from the sales of securities available for sale were $0.0 million and $97.2 million for the three and six months ended March 31, 2019, respectively. No gross gains (pre-tax) were realized on the sales for the three and six months ended March 31, 2020 and 2019, using the specific identification method. Nominal gross losses (pre-tax) were realized on the sales for the three months ended March 31, 2020 and 2019, and nominal and $0.5 million gross losses (pre-tax) were realized on the sales for the six months ended March 31, 2020 and 2019, respectively, using the specific identification method. The Company recognized no other-than-temporary impairment for the three and six months ended March 31, 2020 and 2019. Securities with an estimated fair value of approximately $918.8 million and $863.9 million at March 31, 2020 and September 30, 2019, respectively, were pledged as collateral on public deposits, securities sold under agreements to repurchase, and for other purposes as required by contractual obligation or law. The counterparties do not have the right to sell or pledge the securities the Company has pledged as collateral. As detailed in the following tables, certain investments in debt securities, which are approximately 12% and 36% of the Company’s investment portfolio at estimated fair value at March 31, 2020 and September 30, 2019, respectively, are reported in the consolidated financial statements at an amount less than their amortized cost. Based on evaluation of available evidence, including recent changes in market interest rates, credit rating information, implicit or explicit government guarantees, and information obtained from regulatory filings, management believes the declines in fair value of these securities are temporary. As the Company does not intend to sell the securities and it is not more-likely-than-not the Company will be required to sell the securities before the recovery of their amortized cost basis, which may be maturity, the Company does not consider the securities to be other-than-temporarily impaired at March 31, 2020 or September 30, 2019. The following table presents the Company’s gross unrealized losses and approximate fair value in investments, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position. Less than 12 months 12 months or more Total Estimated Unrealized Estimated Unrealized Estimated Unrealized (dollars in thousands) As of March 31, 2020 U.S. Treasury securities $ — $ — $ — $ — $ — $ — Mortgage-backed securities 30,374 (189) 207,955 (1,344) 238,329 (1,533) States and political subdivision securities — — 9,242 (27) 9,242 (27) Other — — — — — — Total $ 30,374 $ (189) $ 217,197 $ (1,371) $ 247,571 $ (1,560) Less than 12 months 12 months or more Total Estimated Unrealized Estimated Unrealized Estimated Unrealized (dollars in thousands) As of September 30, 2019 U.S. Treasury securities $ — $ — $ 44,729 $ (32) $ 44,729 $ (32) Mortgage-backed securities 94,612 (205) 474,979 (4,144) 569,591 (4,349) States and political subdivision securities — — 23,693 (116) 23,693 (116) Other — — — — — — Total $ 94,612 $ (205) $ 543,401 $ (4,292) $ 638,013 $ (4,497) As of March 31, 2020 and September 30, 2019, the Company had 58 and 169 securities, respectively, in an unrealized loss position.

Loans

Loans	6 Months Ended
	Mar. 31, 2020
Receivables [Abstract]
Loans	Loans The following table presents the composition of loans as of March 31, 2020 and September 30, 2019. March 31, September 30, (dollars in thousands) Commercial real estate $ 5,222,819 $ 5,092,410 Agriculture 1,881,792 2,008,644 Commercial non-real estate 1,699,197 1,719,956 Residential real estate 820,759 812,208 Consumer 52,640 51,925 Other 39,908 47,541 Ending balance 9,717,115 9,732,684 Less: Unamortized discount on acquired loans (10,468) (13,655) Unearned net deferred fees and costs and loans in process (13,352) (12,266) Total $ 9,693,295 $ 9,706,763 The loan segments above include loans covered by a FDIC non-commercial loss sharing agreement totaling $29.7 million and $31.9 million as of March 31, 2020 and September 30, 2019, respectively, residential real estate loans held for sale totaling $4.3 million and $7.4 million at March 31, 2020 and September 30, 2019, respectively, and $792.1 million and $813.0 million of loans accounted for at fair value at March 31, 2020 and September 30, 2019, respectively. Unearned net deferred fees and costs totaled $13.7 million and $13.9 million as of March 31, 2020 and September 30, 2019, respectively. Loans in process represent loans that have been funded as of the balance sheet dates but not classified into a loan category and loan payments received as of the balance sheet dates that have not been applied to individual loan accounts. Loans in process totaled $(0.4) million and $(1.6) million at March 31, 2020 and September 30, 2019, respectively. Loans guaranteed by agencies of the U.S. government totaled $146.2 million and $154.2 million at March 31, 2020 and September 30, 2019, respectively. Principal balances of residential real estate loans sold totaled $68.4 million and $46.8 million for the three months ended March 31, 2020 and 2019, respectively, and $175.4 million and $100.7 million for the six months ended March 31, 2020 and 2019, respectively. Nonaccrual Interest income on loans is accrued daily on the outstanding balances. A loan is placed on nonaccrual status when management believes, after considering collection efforts and other factors, the borrowers' condition is such that collection of interest is doubtful, which is generally 90 days past due. When loans are placed on nonaccrual status, accrual of interest is discontinued and interest receivable is reversed against interest income in the current period. Interest payments received thereafter are applied as a reduction to the remaining principal balance as long as concern exists as to the ultimate collection of the principal. Loans are removed from nonaccrual status when they become current as to both principal and interest and concern no longer exists as to the collectability of principal and interest. The following table presents the Company’s nonaccrual loans at March 31, 2020 and September 30, 2019, excluding ASC 310-30 loans. Loans greater than 90 days past due and still accruing interest as of March 31, 2020 and September 30, 2019, were $2.3 million and $11.2 million, respectively. March 31, September 30, (dollars in thousands) Nonaccrual loans Commercial real estate $ 41,541 $ 14,973 Agriculture 143,198 77,880 Commercial non-real estate 21,334 9,502 Residential real estate 4,437 2,661 Consumer 97 74 Total $ 210,607 $ 105,090 Credit Quality Information The Company assigns all non-consumer loans a credit quality risk rating. These ratings are Pass, Watch, Substandard, Doubtful and Loss. Loans with a Pass and Watch rating represent those loans not classified on the Company’s rating scale as problem credits, with loans with a Watch rating being monitored and updated at least quarterly by management. Substandard loans are those where a well-defined weakness has been identified that may put full collection of contractual debt at risk. Doubtful loans are those where a well-defined weakness has been identified and a loss of contractual debt is probable. Substandard and doubtful loans are monitored and updated monthly. All non-consumer loan risk ratings are monitored by management and updated as deemed appropriate. The Company generally does not risk rate residential real estate or consumer loans unless a default event such as bankruptcy or extended nonperformance takes place. Alternatively, standard credit scoring systems are used to assess credit risks of residential real estate and consumer loans. The following table presents the composition of the loan portfolio by internally assigned grade as of March 31, 2020 and September 30, 2019. This table is presented net of unamortized discount on acquired loans and excludes loans measured at fair value with changes in fair value reported in earnings of $792.1 million at March 31, 2020 and $813.0 million at September 30, 2019. As of March 31, 2020 Commercial Real Estate Agriculture Commercial Residential Real Estate ¹ Consumer ¹ Other Total (dollars in thousands) Credit Risk Profile by Internally Assigned Grade Grade: Pass $ 4,478,193 $ 1,157,671 $ 1,431,706 $ 776,696 $ 51,657 $ 39,908 $ 7,935,831 Watchlist 104,941 229,606 28,859 986 728 — 365,120 Substandard 132,937 345,674 92,849 10,694 122 — 582,276 Doubtful 51 1,437 99 16 4 — 1,607 Loss — — — — — — — Ending balance 4,716,122 1,734,388 1,553,513 788,392 52,511 39,908 8,884,834 Loans covered by a FDIC loss sharing agreement — — — 29,691 — — 29,691 Total $ 4,716,122 $ 1,734,388 $ 1,553,513 $ 818,083 $ 52,511 $ 39,908 $ 8,914,525 1 The Company generally does not risk rate residential real estate or consumer loans unless a default event such as a bankruptcy or extended nonperformance takes place. Alternatively, standard credit scoring systems are used to assess credit risks of residential real estate and consumer loans. As of September 30, 2019 Commercial Real Estate Agriculture Commercial Residential Real Estate ¹ Consumer ¹ Other Total (dollars in thousands) Credit Risk Profile by Internally Assigned Grade Grade: Pass $ 4,433,530 $ 1,346,436 $ 1,424,357 $ 763,797 $ 50,796 $ 47,541 $ 8,066,457 Watchlist 85,256 179,965 103,514 6,297 755 — 375,787 Substandard 54,242 322,327 42,048 6,863 205 — 425,685 Doubtful 56 5,811 296 55 2 — 6,220 Loss — — — — — — — Ending balance 4,573,084 1,854,539 1,570,215 777,012 51,758 47,541 8,874,149 Loans covered by a FDIC loss sharing agreement — — — 31,891 — — 31,891 Total $ 4,573,084 $ 1,854,539 $ 1,570,215 $ 808,903 $ 51,758 $ 47,541 $ 8,906,040 1 The Company generally does not risk rate residential real estate or consumer loans unless a default event such as a bankruptcy or extended nonperformance takes place. Alternatively, standard credit scoring systems are used to assess credit risks of residential real estate and consumer loans. Past Due Loans The following table presents the Company’s past due loans at March 31, 2020 and September 30, 2019. This table is presented net of unamortized discount on acquired loans and excludes loans measured at fair value with changes in fair value reported in earnings of $792.1 million at March 31, 2020 and $813.0 million at September 30, 2019. 30-59 Days Past Due 60-89 Days Past Due 90 Days or Greater Past Due Total Current Total Financing Receivables (dollars in thousands) As of March 31, 2020 Commercial real estate $ 25,351 $ 4,056 $ 13,752 $ 43,159 $ 4,672,963 $ 4,716,122 Agriculture 30,196 10,160 60,176 100,532 1,633,856 1,734,388 Commercial non-real estate 2,538 956 20,497 23,991 1,529,522 1,553,513 Residential real estate 3,702 252 2,550 6,504 781,888 788,392 Consumer 42 5 29 76 52,435 52,511 Other — — — — 39,908 39,908 Ending balance 61,829 15,429 97,004 174,262 8,710,572 8,884,834 Loans covered by a FDIC loss sharing agreement 1,201 319 757 2,277 27,414 29,691 Total $ 63,030 $ 15,748 $ 97,761 $ 176,539 $ 8,737,986 $ 8,914,525 30-59 Days Past Due 60-89 Days Past Due 90 Days or Greater Past Due Total Current Total Financing Receivables (dollars in thousands) As of September 30, 2019 Commercial real estate $ 3,587 $ 570 $ 2,475 $ 6,632 $ 4,566,452 $ 4,573,084 Agriculture 13,411 1,267 33,089 47,767 1,806,772 1,854,539 Commercial non-real estate 3,932 120 4,424 8,476 1,561,739 1,570,215 Residential real estate 311 676 939 1,926 775,086 777,012 Consumer 61 110 7 178 51,580 51,758 Other — — — — 47,541 47,541 Ending balance 21,302 2,743 40,934 64,979 8,809,170 8,874,149 Loans covered by a FDIC loss sharing agreement 536 410 331 1,277 30,614 31,891 Total $ 21,838 $ 3,153 $ 41,265 $ 66,256 $ 8,839,784 $ 8,906,040 Impaired Loans The following table presents the Company’s impaired loans. This table excludes purchased credit impaired loans and loans measured at fair value with changes in fair value reported in earnings of $792.1 million at March 31, 2020 and $813.0 million at September 30, 2019. March 31, 2020 September 30, 2019 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance Related Allowance (dollars in thousands) Impaired loans: With an allowance recorded: Commercial real estate $ 60,619 $ 61,828 $ 7,020 $ 26,003 $ 26,297 $ 4,159 Agriculture 35,013 36,267 8,136 98,392 104,350 8,234 Commercial non-real estate 34,227 37,737 8,601 21,331 21,777 6,062 Residential real estate 5,426 5,923 2,115 3,829 4,311 1,795 Consumer 125 133 36 207 214 97 Total impaired loans with an allowance recorded 135,410 141,888 25,908 149,762 156,949 20,347 With no allowance recorded: Commercial real estate 72,060 110,873 — 28,272 66,631 — Agriculture 312,866 331,126 — 231,087 255,308 — Commercial non-real estate 59,250 67,488 — 21,579 31,414 — Residential real estate 5,475 7,870 — 3,290 5,454 — Consumer 2 110 — 1 108 — Total impaired loans with no allowance recorded 449,653 517,467 — 284,229 358,915 — Total impaired loans $ 585,063 $ 659,355 $ 25,908 $ 433,991 $ 515,864 $ 20,347 The following table presents the average recorded investment on impaired loans and interest income recognized on impaired loans for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status (dollars in thousands) Commercial real estate $ 112,623 $ 1,287 $ 34,475 $ 345 $ 93,174 $ 3,666 $ 36,616 $ 697 Agriculture 369,598 4,784 151,021 2,203 356,225 13,301 146,423 3,202 Commercial non-real estate 97,672 1,531 22,556 312 79,418 4,401 22,731 678 Residential real estate 10,904 127 6,724 93 9,642 393 6,711 182 Consumer 139 3 237 6 162 4 212 11 Total $ 590,936 $ 7,732 $ 215,013 $ 2,959 $ 538,621 $ 21,765 $ 212,693 $ 4,770 Valuation adjustment reductions made to repossessed properties totaled $4.8 million and $0.1 million for the three months ended March 31, 2020 and 2019, respectively. Valuation adjustment reductions made to repossessed properties totaled $4.8 million and $2.0 million for the six months ended March 31, 2020 and 2019, respectively. The adjustments are included in net loss on repossessed property and other related expenses in noninterest expense. Troubled Debt Restructurings Included in certain loan categories in the impaired loans are TDRs that were classified as impaired. These TDRs do not include purchased credit impaired loans. When the Company grants concessions to borrowers such as reduced interest rates or extensions of loan periods that would not be considered other than because of borrowers’ financial difficulties, the modification is considered a TDR. Specific reserves included in the allowance for loan and lease losses for TDRs were $6.9 million and $10.3 million at March 31, 2020 and September 30, 2019, respectively. There were $0.1 million and $0.2 million of commitments to lend additional funds to borrowers whose loans were modified in a TDR as of March 31, 2020 and September 30, 2019, respectively. The following table presents the recorded value of the Company’s TDR balances as of March 31, 2020 and September 30, 2019. March 31, 2020 September 30, 2019 Accruing Nonaccrual Accruing Nonaccrual (dollars in thousands) Commercial real estate $ 19,843 $ 3,088 $ 17,145 $ 904 Agriculture 11,838 20,357 22,929 24,762 Commercial non-real estate 9,402 4,465 4,398 4,257 Residential real estate 294 92 263 102 Consumer 5 40 107 48 Total $ 41,382 $ 28,042 $ 44,842 $ 30,073 TDRs are generally restructured through either a rate modification, term extension, payment modification or due to a bankruptcy. The following table presents a summary of all accruing loans restructured in TDRs for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Recorded Investment Recorded Investment Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Commercial real estate 1 $ 2,879 $ 2,879 — $ — $ — 1 $ 2,879 $ 2,879 — $ — $ — Agriculture 2 993 993 — — — 2 993 993 — — — Commercial non-real estate 2 3,952 3,952 — — — 4 5,096 5,096 — — — Residential real estate 1 50 50 — — — 1 50 50 — — — Consumer — — — — — — — — — 1 89 89 Total accruing 6 $ 7,874 $ 7,874 — $ — $ — 8 $ 9,018 $ 9,018 1 $ 89 $ 89 Change in recorded investment due to principal paydown at time of modification — $ — $ — — $ — $ — — $ — $ — — $ — $ — Change in recorded investment due to chargeoffs at time of modification — — — — — — — — — — — — The following table presents a summary of all nonaccruing loans restructured in TDRs for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Recorded Investment Recorded Investment Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Commercial real estate — $ — $ — — $ — $ — 1 $ 2,216 $ 2,216 — $ — $ — Agriculture — — — — — — 10 1,455 1,455 — — — Commercial non-real estate — — — — — — 2 830 830 — — — Residential real estate — — — — — — — — — — — — Consumer — — — — — — — — — — — — Total nonaccruing — $ — $ — — $ — $ — 13 $ 4,501 $ 4,501 — $ — $ — Change in recorded investment due to principal paydown at time of modification — $ — $ — — $ — $ — — $ — $ — — $ — $ — Change in recorded investment due to chargeoffs at time of modification — — — — — — — — — — — — The following table presents loans that were modified as TDRs within the previous 12 months and for which there was a payment default for the three and six months ended March 31, 2020 and 2019, respectively. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Number of Loans Recorded Investment Number of Loans Recorded Investment Number of Loans Recorded Investment Number of Loans Recorded Investment (dollars in thousands) Commercial real estate — $ — — $ — — $ — — $ — Agriculture 17 2,106 — — 19 11,180 — — Commercial non-real estate — — — — 1 2,834 — — Residential real estate — — — — — — — — Consumer — — — — — — — — Total 17 $ 2,106 — $ — 20 $ 14,014 — $ — For purposes of the table above, a loan is considered to be in payment default once it is 90 days or more contractually past due under the modified terms. The table includes loans that experienced a payment default during the period, but may be performing in accordance with the modified terms as of the balance sheet date. There were $0.3 million and $0.0 million for the three months ended March 31, 2020 and 2019, respectively, and $0.3 million and $0.0 million for the six months ended March 31, 2020 and 2019, respectively, of loans removed from TDR status as they were restructured at market terms and are performing.

Allowance for Loan and Lease Lo

Allowance for Loan and Lease Losses	6 Months Ended
	Mar. 31, 2020
Receivables [Abstract]
Allowance for Loan and Lease Losses	Allowance for Loan and Lease Losses The allowance for loan and lease losses under the incurred loss model is determined based on an ongoing evaluation, driven primarily by monitoring changes in loan risk grades, delinquencies, and other credit risk indicators, which are inherently subjective. The Company considers the uncertainty related to certain industry sectors and the extent of credit exposure to specific borrowers within the portfolio. In addition, consideration is given to concentration risks associated with the various loan portfolios, current economic conditions and other environmental factors that might impact the portfolio. The Company also considers changes, if any, in underwriting activities, the loan portfolio composition (including product mix and geographic, industry, or customer-specific concentrations), trends in loan performance, the level of allowance coverage relative to similar banking institutions under an incurred loss model and macroeconomic factors, such as changes in unemployment rates, gross domestic product, and consumer bankruptcy filings. Changes to the allowance for loan and lease losses are made by charges to the provision for loan and lease losses, which is reflected on the consolidated statements of income. Past due status is monitored as an indicator of credit deterioration. Loans that are 90 days or more past due are put on nonaccrual status unless a repayment is eminent. Loans deemed to be uncollectible are charged off against the allowance for loan and lease losses. Recoveries of amounts previously charged-off are credited to the allowance for loan and lease losses. The allowance for loan and lease losses consist of reserves for probable losses that have been identified related to specific borrowing relationships that are individually evaluated for impairment ("specific reserve"), as well as probable losses inherent in the loan portfolio that are not specifically identified ("collective reserve"). The specific reserve relates to impaired loans. A loan is impaired when, based on current information and events, it is probable the Company will be unable to collect all amounts due (interest as well as principal) according to the contractual terms of the loan agreement. Specific reserves are determined on a loan-by-loan basis based on management’s best estimate of the Company's exposure, given the current payment status of the loan, the present value of expected payments, and the value of any underlying collateral. Impaired loans also include loans modified in TDRs. Generally, the impairment related to troubled debt restructurings is measured based on the fair value of the collateral, less cost to sell, or the present value of expected payments relative to the unpaid principal balance. If the impaired loan is identified as collateral dependent, then the fair value of the collateral method of measuring the amount of the impairment is utilized. This method requires obtaining an independent appraisal of the collateral and reducing the appraised value by applying a discount factor to the appraised value, if necessary, and including costs to sell. Management’s estimate for collective reserves reflects losses incurred in the loan portfolio as of the consolidated balance sheet reporting date. Incurred loss estimates primarily are based on historical loss experience and portfolio mix. Incurred loss estimates may be adjusted for qualitative factors such as current economic conditions and current portfolio trends including credit quality, concentrations, aging of the portfolio, and/or significant policy and underwriting changes, which may not be reflected in the historical loss experience. The following tables present the Company’s allowance for loan and lease losses roll forward for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, 2020 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Beginning balance, January 1, 2020 $ 17,462 $ 32,029 $ 17,389 $ 4,620 $ 288 $ 993 $ 72,781 Charge-offs (1,417) (4,522) (3,577) (118) (25) (707) (10,366) Recoveries 114 1,305 59 147 28 87 1,740 Provision 48,285 714 17,895 3,602 465 738 71,699 (Improvement) impairment of ASC 310-30 loans (30) — — 105 21 — 96 Ending balance, March 31, 2020 $ 64,414 $ 29,526 $ 31,766 $ 8,356 $ 777 $ 1,111 $ 135,950 Three Months Ended March 31, 2019 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Beginning balance, January 1, 2019 $ 16,348 $ 31,785 $ 12,093 $ 4,611 $ 430 $ 926 $ 66,193 Charge-offs (75) (5,767) (110) (310) (85) (249) (6,596) Recoveries 162 199 104 125 44 99 733 Provision (855) 7,508 962 (344) (15) 150 7,406 Impairment of ASC 310-30 loans 23 — — 244 — — 267 Ending balance, March 31, 2019 $ 15,603 $ 33,725 $ 13,049 $ 4,326 $ 374 $ 926 $ 68,003 Six Months Ended March 31, 2020 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Beginning balance, October 1, 2019 $ 16,827 $ 30,819 $ 17,567 $ 4,095 $ 427 $ 1,039 $ 70,774 Charge-offs (1,454) (9,128) (5,059) (287) (45) (1,060) (17,033) Recoveries 234 1,408 172 312 48 137 2,311 Provision 48,857 6,692 19,086 3,794 326 995 79,750 (Improvement) impairment of ASC 310-30 loans (50) (265) — 442 21 — 148 Ending balance, March 31, 2020 $ 64,414 $ 29,526 $ 31,766 $ 8,356 $ 777 $ 1,111 $ 135,950 Six Months Ended iMarch 31, 2019 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Beginning balance, October 1, 2018 $ 16,777 $ 28,121 $ 13,610 $ 4,749 $ 257 $ 1,026 $ 64,540 Charge-offs (946) (7,028) (1,471) (642) (334) (394) (10,815) Recoveries 259 357 228 287 128 131 1,390 Provision (68) 12,275 682 (369) 323 163 13,006 (Improvement) impairment of ASC 310-30 loans (419) — — 301 — — (118) Ending balance, March 31, 2019 $ 15,603 $ 33,725 $ 13,049 $ 4,326 $ 374 $ 926 $ 68,003 The following tables provide details regarding the allowance for loan and lease losses and balance by type of allowance as of March 31, 2020 and September 30, 2019. These tables are presented net of unamortized discount on acquired loans and excludes loans of $792.1 million measured at fair value, loans held for sale of $4.3 million, and guaranteed loans of $138.0 million for March 31, 2020 and loans measured at fair value of $813.0 million, loans held for sale of $7.4 million, and guaranteed loans of $145.9 million for September 30, 2019. As of March 31, 2020 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Allowance for loan and lease losses Individually evaluated for impairment $ 7,020 $ 8,136 $ 8,601 $ 2,115 $ 36 $ — $ 25,908 Collectively evaluated for impairment 57,285 21,390 23,136 5,747 720 1,111 109,389 ASC 310-30 loans 109 — 29 494 21 — 653 Total allowance $ 64,414 $ 29,526 $ 31,766 $ 8,356 $ 777 $ 1,111 $ 135,950 Financing Receivables Individually evaluated for impairment $ 132,679 $ 347,879 $ 93,477 $ 10,901 $ 127 $ — $ 585,063 Collectively evaluated for impairment 4,486,167 1,365,625 1,415,903 774,083 52,001 39,908 8,133,687 ASC 310-30 loans 21,611 2,970 178 28,263 383 — 53,405 Loans Outstanding $ 4,640,457 $ 1,716,474 $ 1,509,558 $ 813,247 $ 52,511 $ 39,908 $ 8,772,155 As of September 30, 2019 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Allowance for loan and lease losses Individually evaluated for impairment $ 4,159 $ 8,234 $ 6,062 $ 1,795 $ 97 $ — $ 20,347 Collectively evaluated for impairment 12,509 22,320 11,476 2,188 330 1,039 49,862 ASC 310-30 loans 159 265 29 112 — — 565 Total allowance $ 16,827 $ 30,819 $ 17,567 $ 4,095 $ 427 $ 1,039 $ 70,774 Financing Receivables Individually evaluated for impairment $ 54,275 $ 329,479 $ 42,910 $ 7,119 $ 208 $ — $ 433,991 Collectively evaluated for impairment 4,418,611 1,501,164 1,480,949 763,645 51,112 47,541 8,263,022 ASC 310-30 loans 22,124 2,756 221 30,280 438 — 55,819 Loans Outstanding $ 4,495,010 $ 1,833,399 $ 1,524,080 $ 801,044 $ 51,758 $ 47,541 $ 8,752,832 For acquired loans not accounted for under ASC 310-30 (purchased non-impaired), the Company utilizes specific and collective reserve calculation methods similar to originated loans. The required ALLL for these loans is included in the individually evaluated for impairment bucket of the ALLL if the loan is rated substandard or worse, and in the collectively evaluated for impairment bucket for pass rated loans. The Company maintains an ALLL for acquired loans accounted for under ASC 310-30 as a result of impairment to loan pools arising from the periodic re-valuation of these loans. Any impairment in the individual pool is generally recognized in the current period as provision for loan and lease losses. Any improvement in the estimated cash flows, is generally not recognized immediately, but is instead reflected as an adjustment to the related loan pools yield on a prospective basis once any previously recorded impairment has been recaptured. The ALLL for ASC 310-30 loans totaled $0.7 million and $0.6 million at March 31, 2020 and September 30, 2019, respectively. For both the three and six months ended March 31, 2020, loan pools accounted for under ASC 310-30 had a net impairment of provision of $0.1 million. For the three and six months ended March 31, 2019, loan pools accounted for under ASC 310-30 had a net impairment of $0.3 million and a net reversal of provision of $0.1 million, respectively. The reserve for unfunded loan commitments was $1.1 million and $0.5 million at March 31, 2020 and September 30, 2019, respectively and is recorded in accrued expenses and other liabilities on the consolidated balance sheets.

Accounting for Certain Loans Ac

Accounting for Certain Loans Acquired with Deteriorated Credit Quality	6 Months Ended
	Mar. 31, 2020
Receivables [Abstract]
Accounting for Certain Loans Acquired with Deteriorated Credit Quality	Accounting for Certain Loans Acquired with Deteriorated Credit Quality In June 2010 and May 2016, the Company acquired certain loans in the TierOne Bank and HF Financial transactions, respectively, that had deteriorated credit quality known as ASC 310-30 loans or purchased credit impaired loans. Several factors were considered when evaluating whether a loan was considered a purchased credit impaired loan, including the delinquency status of the loan, updated borrower credit status, geographic information and updated loan-to-values. Further, these purchased credit impaired loans had differences between contractual amounts owed and cash flows expected to be collected, that were at least in part, due to credit quality. U.S. GAAP allows purchasers to aggregate purchased credit impaired loans acquired in the same fiscal quarter in one or more pools, provided that the loans have common risk characteristics. A pool is then accounted for as a single asset with a single composite interest rate and an aggregate expectation of cash flows. Loan pools are periodically reassessed to determine expected cash flows. In determining the expected cash flows, the timing of cash flows and prepayment assumptions for smaller, homogeneous loans are based on statistical models that take into account factors such as the loan interest rate, credit profile of the borrowers, the years in which the loans were originated, and whether the loans are fixed or variable rate loans. Prepayments may be assumed on large individual loans that consider similar prepayment factors listed above for smaller homogeneous loans. The re-assessment of purchased credit impaired loans resulted in the following changes in the accretable yield during the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 (dollars in thousands) Balance, beginning of period $ 21,130 $ 35,493 $ 26,047 $ 34,973 Accretion (1,753) (2,188) (3,693) (4,343) Reclassification (to) from nonaccretable difference (37) 375 (3,014) 3,050 Balance, end of period $ 19,340 $ 33,680 $ 19,340 $ 33,680 The reclassifications (to) from nonaccretable difference noted in the table above represent instances where specific pools of loans are expected to perform better over the remaining lives of the loans than expected at the prior re-assessment date. The following table provides purchased credit impaired loans at March 31, 2020 and September 30, 2019. March 31, 2020 September 30, 2019 Outstanding Balance ¹ Recorded Investment ² Carrying Value ³ Outstanding Balance ¹ Recorded Investment ² Carrying Value ³ (dollars in thousands) Commercial real estate $ 88,443 $ 21,611 $ 21,502 $ 90,295 $ 22,124 $ 21,965 Agriculture 4,259 2,970 2,970 4,462 2,756 2,491 Commercial non-real estate 7,072 178 149 7,190 221 192 Residential real estate 32,947 28,263 27,769 35,413 30,280 30,168 Consumer 441 383 362 493 438 438 Total lending $ 133,162 $ 53,405 $ 52,752 $ 137,853 $ 55,819 $ 55,254 1 Represents the legal balance of ASC 310-30 loans. 2 Represents the book balance of ASC 310-30 loans. 3 Represents the book balance of ASC 310-30 loans net of the related allowance for loan and lease losses.

FDIC Indemnification Asset

FDIC Indemnification Asset	6 Months Ended
	Mar. 31, 2020
Banking and Thrift [Abstract]
FDIC Indemnification Asset	FDIC Indemnification AssetUnder the terms of the purchase and assumption agreement with the FDIC with regard to the TierOne Bank acquisition, the Company is reimbursed for a portion of the losses incurred on covered assets under the non-commercial loss share agreement. As covered assets are resolved, whether through repayment, short sale of the underlying collateral, the foreclosure on or sale of collateral, or the sale or charge-off of loans or other repossessed property, any differences between the carrying value of the covered assets versus the payments received during the resolution process that are reimbursable by the FDIC are recognized as reductions in the FDIC indemnification asset. Any gains or losses realized from the resolution of covered assets reduce or increase, respectively, the amount recoverable from the FDIC. The following table represents a summary of the activity related to the FDIC indemnification asset for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 (dollars in thousands) Balance, beginning of period $ 832 $ 1,950 $ 1,079 $ 2,502 Amortization (390) (360) (641) (853) Changes in expected reimbursements from FDIC for changes in expected credit losses — (13) — (13) Changes in reimbursable expenses — (16) — (41) Payments (reimbursements) of covered losses to (from) the FDIC 39 (9) 43 (43) Balance, end of period $ 481 $ 1,552 $ 481 $ 1,552 The loss claims filed are subject to review, approval, and annual audits by the FDIC or its assigned agents for compliance with the terms in the loss sharing agreement which ends June 4, 2020.

Derivative Financial Instrument

Derivative Financial Instruments	6 Months Ended
	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments The Company uses interest rate swaps and interest rate caps/floors to manage its interest rate risk and market risk in accommodating the needs of its customers. Interest rate swaps include both traditional interest rate swaps and interest rate swaps which can be canceled by the customer on specified dates at no cost, typically referred to as swaptions. The Company recognizes all derivatives on the consolidated balance sheet at fair value in either other assets or accrued expenses and other liabilities as appropriate. The following table presents the notional amounts and gross fair values of all derivative assets and liabilities held by the Company as of March 31, 2020 and September 30, 2019. March 31, 2020 September 30, 2019 Notional Amount Gross Asset Gross Liability Notional Amount Gross Asset Gross Liability (dollars in thousands) Derivatives not designated as hedging instruments: Interest rate swaps Financial institution counterparties $ 1,279,918 $ — $ (68,412) $ 1,259,765 $ 35 $ (38,755) Customer counterparties 574,453 83,802 — 499,643 48,652 — Interest rate caps Financial institution counterparties 3,438 4 — 100 2 — Customer counterparties 3,438 — (4) 100 — (2) Risk participation agreements 78,194 — (593) 56,833 — (58) Mortgage loan commitments 170,012 636 — 56,665 — (11) Mortgage loan forward sale contracts 166,683 — (636) 61,872 11 — Total $ 2,276,136 $ 84,442 $ (69,645) $ 1,934,978 $ 48,700 $ (38,826) Netting of Derivatives The Company records the derivatives on a net basis when a right of offset exists, based on transactions with a single counterparty that are subject to a legally enforceable master netting agreement. When bilateral netting agreements or similar agreements exist between the Company and its counterparties that create a single legal claim or obligation to pay or receive the net amount in settlement of the individual derivative contracts, the Company reports derivative assets and liabilities on a net by derivative contract by counterparty basis. The following tables provide information on the Company's netting adjustments as of March 31, 2020 and September 30, 2019. Gross Fair Value Fair Value Offset Amount Cash Collateral Net Amount Presented on the Consolidated Balance Sheet (dollars in thousands) As of March 31, 2020 Total Derivative Assets $ 84,442 $ (6,922) $ 21,203 $ 98,723 Total Derivative Liabilities ¹ (69,645) 6,922 62,083 (640) 1 There was an additional $23.6 million of collateral held for initial margin with a Futures Clearing Merchant for clearing derivatives at March 31, 2020 and is included in other assets in the consolidated balance sheets. Gross Fair Value Fair Value Offset Amount Cash Collateral Net Amount Presented on the Consolidated Balance Sheet (dollars in thousands) As of September 30, 2019 Total Derivative Assets $ 48,700 $ (2,445) $ 12,279 $ 58,534 Total Derivative Liabilities ¹ (38,826) 2,445 36,368 (13) 1 There was an additional $18.3 million of collateral held for initial margin with a Futures Clearing Merchant for clearing derivatives at September 30, 2019 and is included in other assets in the consolidated balance sheets. As with any financial instrument, derivative financial instruments have inherent risk including adverse changes in interest rates. The Company’s exposure to derivative credit risk is defined as the possibility of sustaining a loss due to the failure of the counterparty to perform in accordance with the terms of the contract. Credit risks associated with interest rate swaps are similar to those relating to traditional on-balance sheet financial instruments. The Company manages interest rate swap credit risk with the same standards and procedures applied to its commercial lending activities. Credit-risk-related contingent features The Company has agreements with its derivative counterparties that contain a provision where if the Company or the derivative counterparty fails to maintain its status as a well/adequately capitalized institution, then the other party has the right to terminate the derivative positions and the Company or the derivative counterparty would be required to settle its obligations under the agreements. The Company has minimum collateral pledging thresholds with its Swap Dealers and Futures Clearing Merchant. In 2018, the Company entered into RPAs with some of its derivative counterparties to assume the credit exposure related to interest rate derivative contracts. The Company's loan customer enters into an interest rate swap directly with a derivative counterparty and the Company agrees through an RPA to take on the counterparty's risk of loss on the interest rate swap due to a default by the customer. The effect of derivatives on the consolidated statements of income for the three and six months ended March 31, 2020 and 2019 was as follows. Amount of Loss Recognized in Consolidated Statements of Income Three Months Ended March 31, Six Months Ended March 31, Location of Loss Recognized in Consolidated Statements of Income 2020 2019 2020 2019 (dollars in thousands) Derivatives not designated as hedging instruments: Interest rate swaps and other derivatives Net realized and unrealized loss on derivatives $ (50,214) $ (11,032) $ (36,698) $ (29,348) Mortgage loan commitments Net realized and unrealized loss on derivatives 620 9 648 21 Mortgage loan forward sale contracts Net realized and unrealized loss on derivatives (620) (9) (648) (21)

The Fair Value Option for Certa

The Fair Value Option for Certain Loans	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
The Fair Value Option For Certain Loans	The Fair Value Option for Certain Loans The Company has elected to measure certain long-term loans at fair value to assist in managing the interest rate risk for longer-term loans. This fair value option was elected upon the origination of these loans. Interest income is recognized in the same manner as interest on non-fair value loans. See Note 18 for additional disclosures regarding the fair value of the fair value option loans. Long-term loans for which the fair value option has been elected had a net favorable difference between the aggregate fair value and the aggregate unpaid loan principal balance and written loan commitment amount of approximately $57.5 million at March 31, 2020 and a net favorable difference of approximately $34.2 million at September 30, 2019. The total unpaid principal balance of these long-term loans was approximately $734.6 million and $778.8 million at March 31, 2020 and September 30, 2019, respectively. The fair value of these loans is included in total loans in the consolidated balance sheets and are grouped with commercial real estate, agricultural and commercial non-real estate loans in Note 4. As of March 31, 2020 and September 30, 2019, there were loans with a fair value of $9.1 million and $16.5 million, respectively, which were greater than 90 days past due or in nonaccrual status with an unpaid principal balance of $12.1 million and $17.8 million, respectively. Changes in fair value for items for which the fair value option has been elected were an increase in fair value of $35.5 million and $20.6 million for the three and six months ended March 31, 2020, respectively, and an increase in fair value of $14.0 million and $33.2 million for the three and six months ended March 31, 2019, respectively. These changes in fair value are reported in noninterest income (loss) within the consolidated statements of income. For long-term loans, $10.5 million and $12.7 million for the three and six months ended March 31, 2020, respectively, and $0.4 million and $0.8 million for the three and six months ended March 31, 2019, respectively, of the total change in fair value is attributable to changes in specific credit risk. The gains or losses attributable to changes in instrument-specific credit risk were determined based on an assessment of existing market conditions and credit quality of the underlying loan for the specific portfolio of loans.

Goodwill

Goodwill	6 Months Ended
	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill The following table presents the Company's carrying amount of goodwill as of March 31, 2020 and September 30, 2019. March 31, September 30, (dollars in thousands) Balance, beginning of period $ 739,023 $ 739,023 Goodwill acquired during the period 1,539 — Goodwill impairment during the period (740,562) — Balance, end of period $ — $ 739,023 In accordance with ASC 350-20, the Company conducts a goodwill impairment test at least annually, or more frequently as events occur or circumstances change that would more-likely-than-not reduce the fair value below its carrying amount. In the second quarter of fiscal year 2020, the onset of the COVID-19 pandemic prompted the Company to assess qualitative and quantitative factors to determine whether it was more-likely-than-not the fair value of the Company was less than the carrying amount. The Company assessed relevant events and circumstances, including macroeconomic conditions, industry and market considerations, overall financial performance, changes in the composition or carrying amount of assets and liabilities, the market price of the Company's common stock and other relevant facts. The Company performed both a market capitalization approach and a discounted cash flow approach to determine the fair value of the Company. As a result of the analysis, the Company recognized a goodwill impairment charge of $740.6 million for both the three and six months ended March 31, 2020. No goodwill impairment charge was recognized for the three and six months ended March 31, 2019.

Core Deposits and Other Intangi

Core Deposits and Other Intangibles	6 Months Ended
	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Core Deposits and Other Intangibles	Core Deposits and Other Intangibles The following table presents a summary of intangible assets subject to amortization as of March 31, 2020 and September 30, 2019. Core Deposit Intangible Brand Customer Relationships Intangible Other Total (dollars in thousands) As of March 31, 2020 Gross carrying amount $ 7,339 $ — $ 3,172 $ 538 $ 11,049 Accumulated amortization (3,933) — (122) (291) (4,346) Net intangible assets $ 3,406 $ — $ 3,050 $ 247 $ 6,703 As of September 30, 2019 Gross carrying amount $ 7,339 $ 8,464 $ — $ 538 $ 16,341 Accumulated amortization (3,518) (6,392) — (257) (10,167) Net intangible assets $ 3,821 $ 2,072 $ — $ 281 $ 6,174 Amortization expense of intangible assets were $0.4 million and $0.9 million for the three and six months ended March 31, 2020, respectively, and $0.4 million and $0.8 million for the three and six months ended March 31, 2019, respectively. In the second quarter of fiscal year 2020, the onset of the COVID-19 pandemic prompted the Company to assess its intangible assets for impairment. The Company believed the brand intangible asset was closely aligned with the goodwill of the Company, which was determined to be impaired as of March 31, 2020. As a result, the Company recognized an intangible asset impairment of $1.8 million for both the three and six months ended March 31, 2020. No intangible asset impairment charge was recognized for the three and six months ended March 31, 2019. The estimated amortization expense of intangible assets assumes no activities, such as acquisitions, which would result in additional amortizable intangible assets. Estimated amortization expense of intangible assets in subsequent fiscal years is as follows. Fiscal year Amount (dollars in thousands) Remaining in 2020 $ 538 2021 1,014 2022 929 2023 831 2024 742 2025 and thereafter 2,649 Total $ 6,703

Leases

Leases	6 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Leases	Leases ASC Topic 842, Leases ("ASC 842"), became effective for the Company on October 1, 2019. ASC 842 requires a lease, whether classified as an operating lease or a financing lease, be accounted for as a right-of-use asset ("ROU asset") with a related lease liability recorded at the present value of the lease payments. The ROU asset represents the Company's right to use an underlying asset for the lease term and is included in other assets on the Company's consolidated balance sheets. The lease liability represents the Company's obligation to make lease payments and is included in accrued expenses and other liabilities on the Company's consolidated balance sheets. The cost of the lease is recognized on a straight-line basis over the lease term as lease expense. As permitted by ASC 842, the Company elected not to reassess (i) whether any expired or existing contracts are leases or contain leases, (ii) the lease classification of any expired or existing leases, and (iii) the initial direct costs for existing leases. Subsequent to the adoption of ASC 842, the Company assesses contracts at inception to determine whether the contract is a lease or contains an embedded lease. A ROU asset and lease liability is recorded on the consolidated balance sheet for all leases except those with an original lease term of twelve months or less. Most of these leases include one or more renewal options, and certain leases also include lessee termination options. As these renewal options are not generally considered reasonably certain of exercise, they are not included in the lease term. The Company leases certain branch and corporate offices, land and ATM facilities through operating leases with terms typically ranging from 1 to 15 years, with the longest term having a lease expiration of March 31, 2034. The Company has no significant financing leases as of March 31, 2020. The following table summarizes the ROU asset and lease liability as of March 31, 2020. March 31, 2020 (dollars in thousands) ROU asset $ 23,143 Total lease liability 24,036 Weighted average remaining lease term 6.7 years Weighted average discount rate ¹ 1.98 % 1 The Company uses its incremental borrowing rate to calculate the present value of lease payments when the interest rate implicit in the lease is not disclosed. Total lease expense incurred by the Company was $1.9 million and $3.6 million for the three and six months ended March 31, 2020, respectively, principally made up of contractual lease payments for operating leases. As of March 31, 2020, the Company had no operating leases that had not yet commenced. The following table presents supplemental cash flow information related to leases for the three and six months ended March 31, 2020: Three Months Ended March 31, 2020 Six Months Ended March 31, 2020 (dollars in thousands) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows paid for operating leases $ 1,416 $ 2,826 Right-of-use assets obtained in exchange for lease liabilities: Operating leases $ 5,007 $ 5,631 The following table presents a maturity analysis of the Company's operating lease liability as of March 31, 2020. Fiscal year Amount (dollars in thousands) Remaining in 2020 $ 2,832 2021 4,741 2022 4,049 2023 3,580 2024 3,072 2025 and thereafter 7,500 Total undiscounted lease payments 25,774 Less: Amounts representing interest (1,738) Lease liability $ 24,036

Securities Sold Under Agreement

Securities Sold Under Agreements to Repurchase	6 Months Ended
	Mar. 31, 2020
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities Sold Under Agreements to Repurchase	Securities Sold Under Agreements to Repurchase Securities sold under agreements to repurchase generally mature overnight following the transaction date. Securities underlying the agreements had an amortized cost of approximately $81.4 million and $94.7 million and fair value of approximately $83.0 million and $94.4 million at March 31, 2020 and September 30, 2019, respectively. In most cases, in alignment with the repurchase agreements in place with customers, the Company over-collateralizes the agreements at 102% of total funds borrowed to protect the purchaser from changes in market value. Additionally, the Company utilizes held-in-custody procedures to ensure the securities sold under repurchase agreements are unencumbered. The following tables present the gross obligation by the class of collateral pledged and the remaining contractual maturity of the agreements at March 31, 2020 and September 30, 2019. March 31, 2020 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater than 90 Days Total (dollars in thousands) Repurchase agreements Mortgage-backed securities $ 64,809 $ — $ — $ — $ 64,809 Total repurchase agreements $ 64,809 $ — $ — $ — $ 64,809 September 30, 2019 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater than 90 Days Total (dollars in thousands) Repurchase agreements Mortgage-backed securities $ 68,992 $ — $ — $ — $ 68,992 Total repurchase agreements $ 68,992 $ — $ — $ — $ 68,992

FHLB Advances and Other Borrowi

FHLB Advances and Other Borrowings	6 Months Ended
	Mar. 31, 2020
Federal Home Loan Banks [Abstract]
FHLB Advances and Other Borrowings	FHLB Advances and Other Borrowings FHLB advances and other borrowings consist of the following at March 31, 2020 and September 30, 2019. March 31, September 30, (dollars in thousands) Short-term borrowings: Notes payable to FHLB, interest rates from 0.37% to 0.74%, maturing in April 2020 and May 2020 $ 400,000 $ — FHLB fed funds advance, interest rate of 0.35%, matured in April 2020 75,000 15,000 Long-term borrowings: Notes payable to FHLB, interest rates from 2.36% to 3.66% and maturity dates from March 2021 to September 2024 collateralized by real estate loans, with various call dates at the option of the FHLB 325,000 325,000 Total $ 800,000 $ 340,000 As of March 31, 2020 and September 30, 2019, the Company had a borrowing capacity of $1.23 billion and $1.44 billion, respectively, with the FRB Discount Window. Principal balances of loans pledged to FRB Discount Window to collateralize the borrowing totaled $1.48 billion at March 31, 2020 and $1.72 billion at September 30, 2019. The Company has secured this line for contingency funding. As of March 31, 2020 and September 30, 2019, based on its collateral pledged, the additional borrowing capacity of the Company with the FHLB was $1.46 billion and $1.80 billion, respectively. Principal balances of loans pledged to the FHLB to collateralize notes payable totaled $4.11 billion and $4.20 billion at March 31, 2020 and September 30, 2019, respectively. The Company purchased letters of credit from the FHLB to pledge as collateral on public deposits. The amount outstanding was $0.0 million and $170.0 million at March 31, 2020 and September 30, 2019, respectively. The Company had additional letters of credit from the FHLB of $14.5 million and $14.9 million at March 31, 2020 and September 30, 2019, respectively, for other purposes. As of March 31, 2020, FHLB advances and other borrowings are due or callable (whichever is earlier) in subsequent fiscal years as follows. Fiscal year Amount (dollars in thousands) Remaining in 2020 $ 475,000 2021 120,000 2022 60,000 2023 85,000 2024 60,000 2025 and thereafter — Total $ 800,000

Subordinated Debentures and Sub

Subordinated Debentures and Subordinated Notes Payable	6 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Subordinated Debentures and Subordinated Notes Payable	Subordinated Debentures and Subordinated Notes Payable Junior Subordinated Deferrable Interest Debentures The Company has seven trusts which were created or assumed as part of prior acquisitions that as of March 31, 2020 have 73,400 shares in the aggregate issued and outstanding, $1,000 par value, of Company Obligated Mandatorily Redeemable Preferred Securities ("Preferred Securities"). These seven trusts were established and exist for the sole purpose of issuing Preferred Securities and investing the proceeds in junior subordinated deferrable interest debentures ("Debentures") issued by the Company. The Debentures constitute the sole assets of the seven trusts. The Preferred Securities provide for cumulative cash distributions calculated at a rate based on three month LIBOR plus a range from 1.48% to 3.35% adjusted quarterly. The Company may, at one or more times, defer interest payments on the Debentures for up to 20 consecutive quarters following suspension of dividends on all capital stock, but not beyond the respective maturity date. At the end of any deferral period, all accumulated and unpaid interest must be paid. The Debentures have redemption dates ranging from January 7, 2033 to October 1, 2037; however, the Company has the option to shorten the respective maturity date for all seven Preferred Securities as the initial call option date has passed. Holders of the Preferred Securities have no voting rights. The Preferred Securities are unsecured and rank junior in priority of the payment to all of the Company's indebtedness and senior to the Company's common and preferred stock. The trusts’ ability to pay amounts due on the Preferred Securities is solely dependent upon the Company making payment on the related Debentures. The Company’s obligation under the Debentures and relevant trust agreements constitute a full, irrevocable, and unconditional guarantee on a subordinated basis by it of the obligations of the trusts under the Preferred Securities. For regulatory purposes, the Debentures qualify as elements of capital. As of March 31, 2020 and September 30, 2019, Debentures, net of fair value adjustment, of $73.8 million and $73.7 million, respectively, were eligible for treatment as Tier 1 capital. Relating to the trusts, the Company held as assets $2.5 million in common shares at March 31, 2020 and September 30, 2019, which are included in other assets on the consolidated balance sheets. Subordinated Notes Payable In 2015, the Company issued $35.0 million of 4.875% fixed-to-floating rate subordinated notes that mature on August 15, 2025 through a private placement. The notes, which qualify as Tier 2 capital under Capital Rules in effect at March 31, 2020, have an interest rate of 4.875% per annum, payable semi-annually on each February 15 and August 15, which commenced on February 15, 2016 until August 15, 2020, or the date of earlier redemption, and then from August 15, 2020 to the stated maturity date or earlier redemption, the notes will bear interest at a rate per annum equal to three month LIBOR for the related interest period plus 3.15%, payable quarterly on each November 15, February 15, April 15 and August 15. The notes are subordinated in right of payment to all of the Company's senior indebtedness and effectively subordinated to all existing and future debt and all other liabilities of the Company's subsidiary bank. The Company may elect to redeem the notes (subject to regulatory approval), in whole or in part, on any early redemption date which is any interest payment date on or after August 15, 2020 at a redemption price equal to 100% of the principal amount plus any accrued and unpaid interest. Other than on an early redemption date, the notes cannot be accelerated except upon certain events of bankruptcy, insolvency or reorganization. Unamortized debt issuance costs related to these notes, which are included in Subordinated Debentures and Subordinated Notes Payable, were negligible and $0.1 million at March 31, 2020 and September 30, 2019, respectively. Proceeds from the private placement of subordinated notes repaid outstanding subordinated debt. Subordinated debentures and subordinated notes payable are summarized as follows. March 31, 2020 September 30, 2019 Amount Outstanding Common Shares Held in Other Assets Amount Outstanding Common Shares Held in Other Assets (dollars in thousands) Junior subordinated debentures payable to non-consolidated trusts GW Statutory Trust IV, variable rate of 2.85%, plus 3 month LIBOR $ 23,093 $ 693 $ 23,093 $ 693 GW Statutory Trust VI, variable rate of 1.48%, plus 3 month LIBOR 30,928 928 30,928 928 SSB Trust II, variable rate of 1.85%, plus 3 month LIBOR 2,062 62 2,062 62 HF Capital Trust III, variable rate of 3.35%, plus 3 month LIBOR 5,155 155 5,155 155 HF Capital Trust IV, variable rate of 3.10%, plus 3 month LIBOR 7,217 217 7,217 217 HF Capital Trust V, variable rate of 1.83%, plus 3 month LIBOR 5,310 310 5,310 310 HF Capital Trust VI, variable rate of 1.65%, plus 3 month LIBOR 2,155 155 2,155 155 Total junior subordinated debentures payable 75,920 $ 2,520 75,920 $ 2,520 Less: fair value adjustment ¹ (2,155) (2,223) Total junior subordinated debentures payable, net of fair value adjustment 73,765 73,697 Subordinated notes payable Fixed to floating rate, 4.875% per annum 35,000 35,000 Less: unamortized debt issuance costs (25) (61) Total subordinated notes payable 34,975 34,939 Total subordinated debentures and subordinated notes payable $ 108,740 $ 108,636 1 Adjustment reflects the fair value adjustments related to the junior subordinated deferrable interest debentures assumed as part of the HF Financial acquisition.

Profit Sharing Plan

Profit Sharing Plan	6 Months Ended
	Mar. 31, 2020
Retirement Benefits [Abstract]
Profit Sharing Plan	Profit Sharing PlanThe Company participates in a multiple employer 401(k) profit sharing plan ("401(k) Plan"). All employees are eligible to participate, beginning with the first day of the month coincident with or immediately following the completion of one year of service and having reached the age of 21. In addition to employee contributions, the Company may contribute discretionary amounts for eligible participants. Contribution rates for participating employees must be equal. The Company contributed $1.6 million and $3.3 million to the 401(k) Plan for the three and six months ended March 31, 2020, respectively, and $1.1 million and $2.9 million for the three and six months ended March 31, 2019, respectively.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation On September 26, 2014, the Board of Directors adopted, and on October 10, 2014, NAB, at that time the Company's controlling shareholder, approved the Great Western Bancorp, Inc. 2014 Omnibus Incentive Compensation Plan ("2014 Plan"), the Great Western Bancorp, Inc. 2014 Non-Employee Director Plan ("2014 Director Plan"), and the Great Western Bancorp, Inc. Executive Incentive Compensation Plan ("Bonus Plan"), collectively ("the Plans"), which provide for the issuance of restricted share units and performance based share units to certain officers, employees and directors of the Company. On February 22, 2018, the Company's stockholders approved amendments to the 2014 Plan and the 2014 Director Plan to increase the number of shares available for future grants under the Plans. The Plans were primarily established to enhance the Company’s ability to attract, retain and motivate employees. The Company’s Board of Directors, the Compensation Committee of the Board of Directors ("Compensation Committee"), or executive management upon delegation of the Compensation Committee has exclusive authority to select the employees and others, including directors, to receive the awards and to establish the terms and conditions of each award made pursuant to the Company’s stock-based compensation plans. Stock units issued under the Company’s restricted and performance based stock plans may not be sold or otherwise transferred until the vesting period has been met and, if applicable, performance objectives have been obtained. During the vesting periods, participants do not have voting rights and dividends are accumulated until the time upon which the award vests. Upon specified events, as defined in the Plans, stock unit awards that have not vested and/or performance hurdles that have not been met will be forfeited. Based on the substantive terms of each award, restricted and performance-based awards are classified as equity awards and accounted for under the treasury stock method. The fair value of equity-classified awards is based on the market price of the stock on the measurement date and is amortized as compensation expense on a straight-line basis over the vesting or performance period. Stock compensation is recognized based on the number of awards to vest using actual forfeiture amounts. For performance-based stock awards, an estimate is made of the number of shares expected to vest as a result of actual performance against the performance targets to determine the amount of compensation expense to be recognized. The estimate is reevaluated quarterly and total compensation expense is adjusted for any change in the current period. Stock-based compensation expense is included in salaries and employee benefits expense in the consolidated statements of income. Stock compensation expense was $1.3 million and $2.9 million for the three and six months ended March 31, 2020, respectively, and $1.4 million and $3.1 million for the three and six months ended March 31, 2019, respectively. Related income tax benefits recognized were $0.3 million and $0.7 million for the three and six months ended March 31, 2020, respectively and $0.4 million and $0.8 million for the three and six months ended March 31, 2019, respectively. The following is a summary of the Plans’ restricted share and performance-based stock award activity as of March 31, 2020 and September 30, 2019. The number of performance shares granted in the following table are reflected at the amount of achievement of the pre-established targets. March 31, 2020 September 30, 2019 Common Weighted-Average Grant Date Fair Value Common Weighted-Average Grant Date Fair Value Restricted Shares Restricted shares, beginning of fiscal year 190,805 $ 37.20 163,287 $ 37.86 Granted 134,185 32.34 106,753 37.27 Vested (83,909) 38.61 (76,210) 38.64 Forfeited (3,109) 36.61 (3,025) 38.67 Canceled — — — — Restricted shares, end of period 237,972 $ 33.97 190,805 $ 37.20 Vested, but not issuable at end of period 62,992 $ 33.98 50,770 $ 33.88 Performance Shares Performance shares, beginning of fiscal year 173,332 $ 38.50 175,196 $ 36.29 Granted (48,753) (49.22) 60,583 32.77 Vested (54,861) 39.43 (59,937) 30.79 Forfeited (3,732) 38.14 (2,510) 39.25 Canceled — — — — Performance shares, end of period 65,986 $ 34.61 173,332 $ 38.50 Vested, but not issuable at end of period 5,612 $ 18.00 5,612 $ 18.00

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company measures, monitors and discloses certain of its assets and liabilities on a fair value basis. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value guidance also establishes a fair value hierarchy that requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The guidance describes the following three levels of inputs that may be used to measure fair value: Level 1 Quoted prices in active markets for identical assets or liabilities; Level 2 Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and Level 3 Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Level 1 inputs are considered to be the most transparent and reliable and Level 3 inputs are considered to be the least transparent and reliable. The Company assumes the use of the principal market to conduct a transaction of each particular asset or liability being measured and then considers the assumptions that market participants would use when pricing the asset or liability. Whenever possible, the Company first looks for quoted prices for identical assets or liabilities in active markets (Level 1 inputs) to value each asset or liability. However, when inputs from identical assets or liabilities on active markets are not available, the Company utilizes market observable data for similar assets and liabilities. The Company maximizes the use of observable inputs and limits the use of unobservable inputs to occasions when observable inputs are not available. The need to use unobservable inputs generally results from the lack of market liquidity of the actual financial instrument or of the underlying collateral. Although in some instances, third party price indications may be available, limited trading activity can challenge the observability of these quotations. Assets and Liabilities Measured at Fair Value on a Recurring Basis Following is a description of the valuation methodologies and inputs used for assets and liabilities measured at fair value on a recurring basis and recognized in the accompanying consolidated balance sheets, as well as the general classification of such assets and liabilities pursuant to the valuation hierarchy. Securities Available for Sale Where quoted market prices are available in an active market, securities are classified within Level 1 of the valuation hierarchy. Level 1 securities include U.S. Treasury securities. If quoted market prices are not available, then fair values are estimated by using pricing models, quoted prices of securities with similar characteristics, or discounted cash flows and classified as Level 2 securities. Level 2 securities include mortgage-backed, states and political subdivisions, and other securities. Where Level 1 or Level 2 inputs are not available, securities are classified within Level 3 of the hierarchy. Level 3 securities were immaterial at March 31, 2020 and September 30, 2019. Interest Rate Swaps and Loans Interest rate swaps are valued by the Company's Swap Dealers using cash flow valuation techniques with observable market data inputs. The fair value of loans accounted for under the fair value option represents the net carrying value of the loan, plus the equal and opposite amount of the value of the swap needed to offset the interest rate risk and an adjustment for credit risk based on the Company's assessment of existing market conditions for the specific portfolio of loans. This is used due to the strict prepayment penalties put in the loan terms to cover the cost of exiting the interest rate swap of the loans in the case of early prepayment or termination. The adjustment for credit risk on loans accounted for under the fair value option is not significant to the overall fair value of the loans. The fair values estimated by the Company's Swap Dealers use interest rates that are observable or that can be corroborated by observable market data and, therefore, are classified within Level 2 of the valuation hierarchy. The Company has entered into Collateral Agreements with its Swap Dealers and Futures Clearing Merchant which entitle it to receive collateral to cover market values on derivatives which are in asset position, thus a credit risk adjustment on interest rate swaps is not warranted. The Company regularly enters into interest rate lock commitments on mortgage loans to be held for sale with corresponding forward sales contracts related to these interest rate lock commitments, the fair values of which are calculated by applying observable market values from Fannie Mae TBA pricing to each interest rate lock commitment and forward sales contract, therefore, are classified within Level 2 of the valuation hierarchy. The Company also has back-to-back swaps with loan customers, with corresponding swaps with an outside third party in exact offsetting terms. Loan Servicing Rights Fair value is determined at a tranche level, based on market prices for comparable mortgage servicing contracts (Level 3), when available, or alternatively based on a valuation model that calculates the present value of estimated future net servicing income. The valuation model utilizes interest rate, prepayment speed, and default rate assumptions that market participants would use in estimating future net servicing income and that can be validated against market data (Level 3). The following table presents the fair value measurements of assets and liabilities recognized in the accompanying consolidated balance sheets measured at fair value on a recurring basis and the level within the fair value hierarchy in which the fair value measurements fall at March 31, 2020 and September 30, 2019. Fair Value Level 1 Level 2 Level 3 (dollars in thousands) As of March 31, 2020 U.S. Treasury securities $ 70,583 $ 70,583 $ — $ — Mortgage-backed securities 1,857,392 — 1,857,392 — States and political subdivision securities 61,001 — 57,015 3,986 Other 1,051 — 1,051 — Total securities available for sale $ 1,990,027 $ 70,583 $ 1,915,458 $ 3,986 Derivatives-assets $ 98,723 $ — $ 98,723 $ — Derivatives-liabilities 640 — 640 — Fair value loans 792,117 — 792,117 — Loan servicing rights 1,863 — — 1,863 As of September 30, 2019 U.S. Treasury securities $ 94,745 $ 94,745 $ — $ — Mortgage-backed securities 1,620,903 — 1,620,903 — States and political subdivision securities 66,523 — 62,403 4,120 Other 1,037 — 1,037 — Total securities available for sale $ 1,783,208 $ 94,745 $ 1,684,343 $ 4,120 Derivatives-assets $ 58,534 $ — $ 58,534 $ — Derivatives-liabilities 13 — 13 — Fair value loans 812,991 — 812,991 — Loan servicing rights 2,255 — — 2,255 The following table presents the changes in Level 3 assets and liabilities measured at fair value on a recurring basis for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 (dollars in thousands) Other securities available for sale Balance, beginning of period $ 3,986 $ 961 $ 4,120 $ 970 Additions — 350 — 350 Principal paydown — — (134) (9) Balance, end of period $ 3,986 $ 1,311 $ 3,986 $ 1,311 Loan servicing rights Balance, beginning of period $ 2,054 $ 2,862 $ 2,255 $ 3,087 Realized and unrealized loss ¹ (191) (188) (392) (413) Balance, end of period $ 1,863 $ 2,674 $ 1,863 $ 2,674 1 Realized and unrealized loss related to loan servicing rights are reported as a component of mortgage banking income, net on the consolidated statements of income. Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis Following is a description of the valuation methodologies used for assets and liabilities measured at fair value on a nonrecurring basis and recognized in the accompanying consolidated balance sheets, as well as the general classification of such assets and liabilities pursuant to the valuation hierarchy. Other Repossessed Property Other repossessed property consists of loan collateral that has been repossessed through foreclosure. This collateral is comprised of commercial and residential real estate and other repossessed assets. Other repossessed property is recorded initially at fair value of the collateral less estimated selling costs. Subsequent to foreclosure, valuations are updated periodically, and the assets may be marked down further to fair value less selling costs, reflecting a valuation allowance. Fair value measurements may be based upon appraisals, third-party price opinions, or internally developed pricing methods. These measurements are classified as Level 3. Impaired Loans (Collateral Dependent) Loans for which it is probable that the Company will not collect all principal and interest due according to contractual terms are measured for impairment. Allowable methods for estimating fair value include using the fair value of the collateral for collateral dependent loans or, where a loan is determined not to be collateral dependent, using the discounted cash flow method. If the impaired loan is identified as collateral dependent, then the fair value method of measuring the amount of the impairment is utilized. This method requires obtaining a current independent appraisal of the collateral and applying a discount factor, if necessary, to the appraised value and including costs to sell. Because many of these inputs are not observable, the measurements are classified as Level 3. Mortgage Loans Held for Sale Fair value of mortgage loans held for sale is based on either quoted prices for the same or similar loans, or values obtained from third parties, or are estimated for portfolios of loans with similar financial characteristics and are therefore considered a Level 2 valuation. Property Held for Sale This real estate property is carried in premises and equipment as property held for sale at fair value based upon the transactional price if available, or the appraised value of the property. The following table presents the fair value measurement of assets and liabilities measured at fair value on a nonrecurring basis and the level within the fair value hierarchy in which the fair value measurements fall at March 31, 2020 and September 30, 2019. Fair Value Level 1 Level 2 Level 3 (dollars in thousands) As of March 31, 2020 Other repossessed property $ 21,486 $ — $ — $ 21,486 Impaired loans 559,155 — — 559,155 Mortgage loans held for sale, at lower of cost or fair value 4,342 — 4,342 — Property held for sale 706 — — 706 As of September 30, 2019 Other repossessed property $ 34,721 $ — $ — $ 34,721 Impaired loans 413,644 — — 413,644 Mortgage loans held for sale, at lower of cost or fair value 7,351 — 7,351 — Property held for sale 2,757 — — 2,757 The valuation techniques and significant unobservable inputs used to measure Level 3 fair value measurements at March 31, 2020 were as follows. Fair Value of Assets / (Liabilities) at March 31, 2020 Valuation Unobservable Range Weighted (dollars in thousands) Other repossessed property $ 21,486 Appraisal value Property specific adjustment N/A N/A Impaired loans 559,155 Appraisal value Property specific adjustment N/A N/A Property held for sale 706 Appraisal value Property specific adjustment N/A N/A Disclosures about Fair Value of Financial Instruments Significant assets and liabilities that are not considered financial instruments are accounted for at amortized cost and include premises and equipment, deferred income taxes, goodwill, and core deposit and other intangibles. Additionally, in accordance with the disclosure guideline, receivables and payables due in one year or less, insurance contracts, equity investments not accounted for at fair value, and deposits with no defined or contractual maturities are excluded. Off-balance sheet instruments (commitments to extend credit and standby letters of credit) are generally short-term and at variable rates. Therefore, both the carrying amount and the estimated fair value associated with these instruments are immaterial. Fair values for on-balance sheet instruments as of March 31, 2020 and September 30, 2019 are as follows. March 31, 2020 September 30, 2019 Level in Fair Value Hierarchy Carrying Amount Fair Carrying Amount Fair (dollars in thousands) Assets Cash and cash equivalents Level 1 $ 347,486 $ 347,486 $ 243,474 $ 243,474 Loans, net, excluding fair valued loans, loans held for sale and impaired loans ¹ Level 3 8,337,681 8,498,042 8,472,777 8,533,612 Liabilities Time deposits Level 2 1,528,234 1,532,200 2,095,676 2,101,239 FHLB advances and other borrowings Level 2 800,000 818,669 340,000 351,517 Securities sold under repurchase agreements Level 2 64,809 64,809 68,992 68,992 Subordinated debentures and subordinated notes payable Level 2 108,740 97,268 108,636 101,164 1 Includes $13.7 million and $13.9 million of net deferred loan fees at March 31, 2020 and September 30, 2019, respectively, of which carrying value approximates fair value.

Earnings per Share

Earnings per Share	6 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share Basic earnings per common share is calculated by dividing net income available to common shareholders by the weighted average number of common shares outstanding during the period. Diluted earnings per common share is calculated by dividing net income available to common shareholders by the weighted average number of common shares outstanding determined for the basic earnings per share calculation plus the dilutive effect of stock compensation using the treasury stock method. The following information was used in the computation of basic and diluted earnings per share (EPS) for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 (dollars in thousands, except per share data) Net income $ (740,618) $ 44,511 $ (697,344) $ 90,297 Weighted average common shares outstanding 55,906,002 56,994,817 56,141,816 57,484,838 Dilutive effect of stock based compensation — 79,857 — 72,146 Weighted average common shares outstanding for diluted earnings per share calculation 55,906,002 57,074,674 56,141,816 57,556,984 Basic earnings per share $ (13.25) $ 0.78 $ (12.42) $ 1.57 Diluted earnings per share $ (13.25) $ 0.78 $ (12.42) $ 1.57 The Company had 5,037 and no shares of unvested performance stock as of March 31, 2020 and 2019, respectively, which were not included in the computation of diluted earnings per common share because performance conditions for vesting had not been met. The Company had 63,076 and 67,971 shares of anti-dilutive stock awards outstanding as of March 31, 2020 and 2019, respectively.

Revenue Recognition

Revenue Recognition	6 Months Ended
	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition The Company recognizes revenue from contracts with customers in accordance with ASC Topic 606, Revenue from Contracts with Customers . The core principle requires an entity to recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration it expects to be entitled to receive in exchange for those goods or services recognized as performance obligations are satisfied. The majority of the Company's revenue-generating transactions are not subject to ASC Topic 606, including revenue generated from financial instruments, such as loans, letters of credit, derivatives and investment securities, as well as revenue related to mortgage servicing activities, as these activities are subject to other GAAP and discussed elsewhere within Item 8. Financial Statements and Supplementary Data, "Note 1. Nature of Operations and Summary of Significant Accounting Policies" in our Annual Report on Form 10-K for the fiscal year ended September 30, 2019. Descriptions of the Company's revenue-generating activities that are within the scope of ASC Topic 606, which are presented in the consolidated income statements as components of noninterest income, are as follows: Service charges and fees on deposit accounts. Service charges on deposit accounts are earned for account maintenance and overdraft, wire and treasury management services. Revenue is recognized at the time the services are performed and is included in service charges and other fees within noninterest income on the consolidated statements of income. Interchange and merchant services income. Interchange and merchant services income are earned from credit and debit card payment processing through card association networks, merchant services and other card related services. Fees for these services are primarily based on interchange rates set by the networks and transaction volumes and are recognized as transactions are processed and settled with networks on behalf of card holders. These fees are presented net of direct expenses, including reward costs, associated with credit and debit card interchange income in service charges and other fees which are included in noninterest income on the consolidated statements of income. Wealth management and trust fee income. Wealth management and trust fees are earned for asset management, custody and recordkeeping, investment advisory and administrative services. Revenue is recognized as the services are performed. Brokerage charges are recorded as a net reduction in wealth management fees which are included in noninterest income on the consolidated statements of income. Other noninterest income. Other noninterest income primarily includes such items as letter of credit fees, gains on sale of loans held for sale and servicing fees, none of which are subject to the requirements of ASC Topic 606. The following table presents total noninterest income segregated between contracts with customers within the scope of ASC Topic 606 and those within the scope of other GAAP Topics. The following additionally presents revenues from customers that are included within noninterest income. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 (dollars in thousands) Noninterest income Service charges and other fees $ 9,188 $ 10,209 $ 20,597 $ 21,897 Wealth management fees 3,122 2,117 6,086 4,358 Other 664 1,118 1,332 1,700 Noninterest income from contracts with customers within the scope of ASC Topic 606 12,974 13,444 28,015 27,955 Noninterest income within the scope of other GAAP Topics ¹ (13,057) 4,779 (12,365) 6,988 Total noninterest income $ (83) $ 18,223 $ 15,650 $ 34,943 1 The Company presents out of scope noninterest income for the purpose of reconciling noninterest income amounts within the scope of ASC Topic 606 to noninterest income amounts presented on the Company's consolidated statements of income.

Acquisition Activity

Acquisition Activity	6 Months Ended
	Mar. 31, 2020
Business Combinations [Abstract]
Acquisition Activity	Acquisition Activity Effective October 1, 2019, the Company purchased and assumed the management of $306.0 million of trust assets managed in Colorado from Independent Bank, a wholly owned subsidiary of Independent Bank Group, Inc., for $4.7 million. The Company accounted for the purchase under the acquisition method in accordance with ASC Topic 805, Business Combinations . Accordingly, the purchase price is allocated to the fair value of the assets acquired and liabilities assumed as of the date of acquisition. The following table summarizes the consideration paid and the allocation of the purchase price to net assets as of the acquisition date. Amount (dollars in thousands) Total consideration paid $4,711 Customer relationship intangible $3,172 Goodwill $1,539 The foregoing purchase price allocation on the acquisition is considered final and no subsequent adjustments to the purchase price allocation are expected. Goodwill related to this acquisition was not deductible for tax purposes. See Note 10 for additional disclosure regarding goodwill. The customer relationship intangible is being amortized over an estimated useful life of 13 years. See Note 11 for additional disclosure regarding intangible assets.

Nature of Operations and Summ_2

Nature of Operations and Summary of Significant Policies (Policies)	6 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated interim financial statements have been prepared in accordance with U.S. GAAP and reflect all adjustments that are, in the opinion of management, necessary for the fair presentation of the financial position and results of operations for the periods presented. All such adjustments are of a normal recurring nature. Certain previously reported amounts have been reclassified to conform to the current presentation. The unaudited interim consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements for the year ended September 30, 2019, which includes a description of significant accounting policies. The results of operations for interim periods are not necessarily indicative of the results that may be expected for the year or any other period. The accompanying unaudited consolidated financial statements include the accounts and results of operations of the Company and its subsidiaries after elimination of all significant intercompany accounts and transactions. The preparation of unaudited consolidated financial statements in conformity with U.S. GAAP requires management to make certain estimates and assumptions that affect the amounts reported on the consolidated financial statements and accompanying notes. Actual results could differ from these estimates.
Subsequent Events	Subsequent Events The Company has evaluated all events or transactions that occurred through the date the Company issued these financial statements. Other than those described below, there were no material events or transactions that would require recognition in the consolidated financial statements or disclosure in the notes to the consolidated financial statements.
New Accounting Standards	Accounting Standards Adopted in Fiscal Year 2020 In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities , which amended the hedge accounting recognition and presentation requirements in ASC 815 to improve the transparency and understandability of information conveyed to financial statement users about an entity’s risk management activities to better align the entity’s financial reporting for hedging relationships with those risk management activities and to reduce the complexity of and simplify the application of hedge accounting. ASU 2017-12 was effective for the Company on October 1, 2019. For the periods presented, the Company did not designate any derivative financial instruments as formal hedging relationships, and therefore, did not utilize hedge accounting. As such, ASU 2017-12 did not impact the Company's consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which requires that lessees recognize the assets and liabilities arising from leases on the balance sheet and disclose key information about leasing arrangements. Lessees are required to recognize an obligation for future lease payments measured on a discounted basis and a related right-of-use asset. ASU 2016-02 does not significantly change lease accounting requirements applicable to lessors; however, certain changes were made to align, where necessary, lessor accounting with the lessee accounting model and ASC Topic 606, Revenue from Contracts with Customers . In July 2018, the FASB issued ASU 2018-10, Codification Improvements to Topic 842, Leases , and ASU 2018-11, Leases (Topic 842), Targeted Improvements , which made technical corrections and improvements to the previous ASU issued, including a modified retrospective transition method that allows entities to apply the standard as of the adoption date. In December 2018, the FASB issued ASU 2018-20, Leases (Topic 842): Narrow-Scope Improvements for Lessors , which allowed lessors to exclude sales tax from consideration of the contract through a policy election and clarified treatment of certain lessor costs and variable payments for contracts with lease and nonlease components. The Company adopted this guidance beginning October 1, 2019 using the modified retrospective transition method and all practical expedients available other than the use of hindsight with respect to determining the lease term and assessing impairment of its right-of-use assets. As of the date of adoption, the Company's right-of-use assets and lease liabilities recorded in other assets and accrued expenses and other liabilities on the consolidated balance sheets were $19.9 million and $20.9 million, respectively, arising from operating leases in which the Company is the lessee. The Company also recognized a cumulative effect adjustment of $0.2 million as a result of remeasuring a pre-existing lease impairment as of the date of adoption. These ASUs did not have a material impact on the timing of expense or income recognition in the Company's consolidated statements of income. Accounting Standards Not Yet Adopted in Fiscal Year 2020 In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes in the Disclosure Requirements for Fair Value Measurement , which eliminates, adds and modifies certain disclosure requirements for fair value measurements. Among the changes, entities will no longer be required to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, but will be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. ASU 2018-13 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. Entities are also allowed to elect to early adopt the eliminated or modified disclosure requirements and delay adoption of the new disclosure requirements until after their effective date. As ASU 2018-13 only revises disclosure requirements, the Company does not believe this ASU will have a material impact on the consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which addresses timelier recording of credit losses on loans and other financial instruments held by financial institutions and other organizations. ASU 2016-13 requires institutions to measure all expected credit losses related to financial assets measured at amortized costs with an expected loss model based on historical experience, current conditions and reasonable and supportable forecasts relevant to affect the collectability of the financial assets, which is referred to as the current expected credit loss model. ASU 2016-13 requires enhanced disclosures, including qualitative and quantitative requirements, to help understand significant estimates and judgments used in estimating credit losses, as well as provide additional information about the amounts recorded in the financial statements. From November 2018 through February 2020, the FASB issued ASUs which made technical corrections and improvements to the previous ASU issued (ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments, Credit Losses; ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments - Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments; ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments - Credit Losses; and ASU 2020-02, Financial Instruments - Credit Losses (Topic 326) and Leases (Topic 842 )). The ASUs require the use of the modified retrospective approach for adoption. These ASUs will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted after December 15, 2018. The Company continues to make progress on its implementation plan including continuing to work through finalizing processes, controls and an independent model validation and we are on track to adopt as required on October 1, 2020. The Company is currently evaluating the potential impact on the consolidated financial statements; however, since the magnitude of the anticipated change in the allowance for credit losses will be impacted by economic conditions and trends in the Company’s portfolio at the time of adoption, the quantitative impact cannot yet be reasonably estimated. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , which aims to simplify the accounting for income taxes by removing certain exceptions to the general principles and also simplification of areas such as franchise taxes, step-up in tax basis goodwill, separate entity financial statements and interim recognition of enactment of tax laws or rate changes. The ASU will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020, with early adoption permitted. The Company is currently evaluating the potential impact of ASU 2019-12 on the consolidated financial statements. In January 2020, the FASB issued ASU 2020-01, Investments - Equity Securities (Topic 321), Investments - Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815): Clarifying the Interactions between Topic 321, Topic 323 and Topic 815 , which clarifies that an entity should consider observable transactions that require it to either apply or discontinue the equity method of accounting for the purposes of applying the fair value measurement alternative. The ASU will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020, with early adoption permitted. The Company does not expect adoption to have a material impact on the consolidated financial statements. In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting , which provides optional expedients and exceptions for a limited time period to ease the potential burden in accounting for reference rate reform on financial reporting. The amendments in ASU 2020-04 are elective for entities with contracts, including derivative contracts, that reference LIBOR or some other reference rate that are expected to be discontinued. For the Company's cash flow hedges, ASU 2020-04 allows: (i) an entity to change the reference rate without having to designate the hedging relationship; (ii) for cash flow hedges in which the designated hedged risk is LIBOR, allows an entity to assert that it remains probable that the hedged forecasted transaction will occur; and (iii) allows an entity to change the designated method used to assess hedge effectiveness and simplifies or temporarily suspends the assessment of hedge effectiveness for hedging relationships. ASU 2020-04 must be applied prospectively and was effective immediately upon issuance and remains effective through December 31, 2022. The Company is currently evaluating the impact that adopting this new accounting standard will have on the consolidated financial statements.
Revenue Recognition	The Company recognizes revenue from contracts with customers in accordance with ASC Topic 606, Revenue from Contracts with Customers . The core principle requires an entity to recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration it expects to be entitled to receive in exchange for those goods or services recognized as performance obligations are satisfied. The majority of the Company's revenue-generating transactions are not subject to ASC Topic 606, including revenue generated from financial instruments, such as loans, letters of credit, derivatives and investment securities, as well as revenue related to mortgage servicing activities, as these activities are subject to other GAAP and discussed elsewhere within Item 8. Financial Statements and Supplementary Data, "Note 1. Nature of Operations and Summary of Significant Accounting Policies" in our Annual Report on Form 10-K for the fiscal year ended September 30, 2019. Descriptions of the Company's revenue-generating activities that are within the scope of ASC Topic 606, which are presented in the consolidated income statements as components of noninterest income, are as follows: Service charges and fees on deposit accounts. Service charges on deposit accounts are earned for account maintenance and overdraft, wire and treasury management services. Revenue is recognized at the time the services are performed and is included in service charges and other fees within noninterest income on the consolidated statements of income. Interchange and merchant services income. Interchange and merchant services income are earned from credit and debit card payment processing through card association networks, merchant services and other card related services. Fees for these services are primarily based on interchange rates set by the networks and transaction volumes and are recognized as transactions are processed and settled with networks on behalf of card holders. These fees are presented net of direct expenses, including reward costs, associated with credit and debit card interchange income in service charges and other fees which are included in noninterest income on the consolidated statements of income. Wealth management and trust fee income. Wealth management and trust fees are earned for asset management, custody and recordkeeping, investment advisory and administrative services. Revenue is recognized as the services are performed. Brokerage charges are recorded as a net reduction in wealth management fees which are included in noninterest income on the consolidated statements of income. Other noninterest income. Other noninterest income primarily includes such items as letter of credit fees, gains on sale of loans held for sale and servicing fees, none of which are subject to the requirements of ASC Topic 606.

Securities Available for Sale (

Securities Available for Sale (Tables)	6 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Schedule of amortized cost and fair value of investments by contractual maturity	The amortized cost and approximate fair value of investments in securities, all of which are classified as available for sale according to management’s intent, are summarized as follows. Amortized Gross Unrealized Gains Gross Unrealized Losses Estimated (dollars in thousands) As of March 31, 2020 U.S. Treasury securities $ 69,629 $ 954 $ — $ 70,583 Mortgage-backed securities: Government National Mortgage Association 566,747 11,340 (733) 577,354 Federal Home Loan Mortgage Corporation 556,535 15,747 (731) 571,551 Federal National Mortgage Association 386,996 15,337 (27) 402,306 Small Business Assistance Program 300,498 5,725 (42) 306,181 States and political subdivision securities 60,511 517 (27) 61,001 Other 1,006 45 — 1,051 Total $ 1,941,922 $ 49,665 $ (1,560) $ 1,990,027 Amortized Gross Unrealized Gains Gross Unrealized Losses Estimated (dollars in thousands) As of September 30, 2019 U.S. Treasury securities $ 94,178 $ 599 $ (32) $ 94,745 Mortgage-backed securities: Government National Mortgage Association 501,139 3,374 (3,027) 501,486 Federal Home Loan Mortgage Corporation 463,974 8,840 (770) 472,044 Federal National Mortgage Association 322,340 5,409 (398) 327,351 Small Business Assistance Program 316,502 3,674 (154) 320,022 States and political subdivision securities 66,145 494 (116) 66,523 Other 1,006 31 — 1,037 Total $ 1,765,284 $ 22,421 $ (4,497) $ 1,783,208 The amortized cost and approximate fair value of debt securities available for sale as of March 31, 2020 and September 30, 2019, by contractual maturity, are shown below. Maturities of mortgage-backed securities may differ from contractual maturities because the mortgages underlying the securities may be called or repaid without penalty. March 31, 2020 September 30, 2019 Amortized Estimated Amortized Estimated (dollars in thousands) Due in one year or less $ 82,615 $ 83,577 $ 58,377 $ 58,343 Due after one year through five years 35,858 36,102 89,836 90,601 Due after five years through ten years 11,667 11,905 12,110 12,324 Due after ten years — — — — 130,140 131,584 160,323 161,268 Mortgage-backed securities 1,810,776 1,857,392 1,603,955 1,620,903 Securities without contractual maturities 1,006 1,051 1,006 1,037 Total $ 1,941,922 $ 1,990,027 $ 1,765,284 $ 1,783,208
Schedule of gross unrealized losses on investments	The following table presents the Company’s gross unrealized losses and approximate fair value in investments, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position. Less than 12 months 12 months or more Total Estimated Unrealized Estimated Unrealized Estimated Unrealized (dollars in thousands) As of March 31, 2020 U.S. Treasury securities $ — $ — $ — $ — $ — $ — Mortgage-backed securities 30,374 (189) 207,955 (1,344) 238,329 (1,533) States and political subdivision securities — — 9,242 (27) 9,242 (27) Other — — — — — — Total $ 30,374 $ (189) $ 217,197 $ (1,371) $ 247,571 $ (1,560) Less than 12 months 12 months or more Total Estimated Unrealized Estimated Unrealized Estimated Unrealized (dollars in thousands) As of September 30, 2019 U.S. Treasury securities $ — $ — $ 44,729 $ (32) $ 44,729 $ (32) Mortgage-backed securities 94,612 (205) 474,979 (4,144) 569,591 (4,349) States and political subdivision securities — — 23,693 (116) 23,693 (116) Other — — — — — — Total $ 94,612 $ (205) $ 543,401 $ (4,292) $ 638,013 $ (4,497)

Loans (Tables)

Loans (Tables)	6 Months Ended
	Mar. 31, 2020
Receivables [Abstract]
Schedule of loans receivable	The following table presents the composition of loans as of March 31, 2020 and September 30, 2019. March 31, September 30, (dollars in thousands) Commercial real estate $ 5,222,819 $ 5,092,410 Agriculture 1,881,792 2,008,644 Commercial non-real estate 1,699,197 1,719,956 Residential real estate 820,759 812,208 Consumer 52,640 51,925 Other 39,908 47,541 Ending balance 9,717,115 9,732,684 Less: Unamortized discount on acquired loans (10,468) (13,655) Unearned net deferred fees and costs and loans in process (13,352) (12,266) Total $ 9,693,295 $ 9,706,763
Schedule of the Company's nonaccrual loans	The following table presents the Company’s nonaccrual loans at March 31, 2020 and September 30, 2019, excluding ASC 310-30 loans. Loans greater than 90 days past due and still accruing interest as of March 31, 2020 and September 30, 2019, were $2.3 million and $11.2 million, respectively. March 31, September 30, (dollars in thousands) Nonaccrual loans Commercial real estate $ 41,541 $ 14,973 Agriculture 143,198 77,880 Commercial non-real estate 21,334 9,502 Residential real estate 4,437 2,661 Consumer 97 74 Total $ 210,607 $ 105,090
Schedule of the composition of the loan portfolio by internal risk rating	This table is presented net of unamortized discount on acquired loans and excludes loans measured at fair value with changes in fair value reported in earnings of $792.1 million at March 31, 2020 and $813.0 million at September 30, 2019. As of March 31, 2020 Commercial Real Estate Agriculture Commercial Residential Real Estate ¹ Consumer ¹ Other Total (dollars in thousands) Credit Risk Profile by Internally Assigned Grade Grade: Pass $ 4,478,193 $ 1,157,671 $ 1,431,706 $ 776,696 $ 51,657 $ 39,908 $ 7,935,831 Watchlist 104,941 229,606 28,859 986 728 — 365,120 Substandard 132,937 345,674 92,849 10,694 122 — 582,276 Doubtful 51 1,437 99 16 4 — 1,607 Loss — — — — — — — Ending balance 4,716,122 1,734,388 1,553,513 788,392 52,511 39,908 8,884,834 Loans covered by a FDIC loss sharing agreement — — — 29,691 — — 29,691 Total $ 4,716,122 $ 1,734,388 $ 1,553,513 $ 818,083 $ 52,511 $ 39,908 $ 8,914,525 1 The Company generally does not risk rate residential real estate or consumer loans unless a default event such as a bankruptcy or extended nonperformance takes place. Alternatively, standard credit scoring systems are used to assess credit risks of residential real estate and consumer loans. As of September 30, 2019 Commercial Real Estate Agriculture Commercial Residential Real Estate ¹ Consumer ¹ Other Total (dollars in thousands) Credit Risk Profile by Internally Assigned Grade Grade: Pass $ 4,433,530 $ 1,346,436 $ 1,424,357 $ 763,797 $ 50,796 $ 47,541 $ 8,066,457 Watchlist 85,256 179,965 103,514 6,297 755 — 375,787 Substandard 54,242 322,327 42,048 6,863 205 — 425,685 Doubtful 56 5,811 296 55 2 — 6,220 Loss — — — — — — — Ending balance 4,573,084 1,854,539 1,570,215 777,012 51,758 47,541 8,874,149 Loans covered by a FDIC loss sharing agreement — — — 31,891 — — 31,891 Total $ 4,573,084 $ 1,854,539 $ 1,570,215 $ 808,903 $ 51,758 $ 47,541 $ 8,906,040 1 The Company generally does not risk rate residential real estate or consumer loans unless a default event such as a bankruptcy or extended nonperformance takes place. Alternatively, standard credit scoring systems are used to assess credit risks of residential real estate and consumer loans.
Schedule of past due loans	The following table presents the Company’s past due loans at March 31, 2020 and September 30, 2019. This table is presented net of unamortized discount on acquired loans and excludes loans measured at fair value with changes in fair value reported in earnings of $792.1 million at March 31, 2020 and $813.0 million at September 30, 2019. 30-59 Days Past Due 60-89 Days Past Due 90 Days or Greater Past Due Total Current Total Financing Receivables (dollars in thousands) As of March 31, 2020 Commercial real estate $ 25,351 $ 4,056 $ 13,752 $ 43,159 $ 4,672,963 $ 4,716,122 Agriculture 30,196 10,160 60,176 100,532 1,633,856 1,734,388 Commercial non-real estate 2,538 956 20,497 23,991 1,529,522 1,553,513 Residential real estate 3,702 252 2,550 6,504 781,888 788,392 Consumer 42 5 29 76 52,435 52,511 Other — — — — 39,908 39,908 Ending balance 61,829 15,429 97,004 174,262 8,710,572 8,884,834 Loans covered by a FDIC loss sharing agreement 1,201 319 757 2,277 27,414 29,691 Total $ 63,030 $ 15,748 $ 97,761 $ 176,539 $ 8,737,986 $ 8,914,525 30-59 Days Past Due 60-89 Days Past Due 90 Days or Greater Past Due Total Current Total Financing Receivables (dollars in thousands) As of September 30, 2019 Commercial real estate $ 3,587 $ 570 $ 2,475 $ 6,632 $ 4,566,452 $ 4,573,084 Agriculture 13,411 1,267 33,089 47,767 1,806,772 1,854,539 Commercial non-real estate 3,932 120 4,424 8,476 1,561,739 1,570,215 Residential real estate 311 676 939 1,926 775,086 777,012 Consumer 61 110 7 178 51,580 51,758 Other — — — — 47,541 47,541 Ending balance 21,302 2,743 40,934 64,979 8,809,170 8,874,149 Loans covered by a FDIC loss sharing agreement 536 410 331 1,277 30,614 31,891 Total $ 21,838 $ 3,153 $ 41,265 $ 66,256 $ 8,839,784 $ 8,906,040
Schedule of impaired loans	The following table presents the Company’s impaired loans. This table excludes purchased credit impaired loans and loans measured at fair value with changes in fair value reported in earnings of $792.1 million at March 31, 2020 and $813.0 million at September 30, 2019. March 31, 2020 September 30, 2019 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance Related Allowance (dollars in thousands) Impaired loans: With an allowance recorded: Commercial real estate $ 60,619 $ 61,828 $ 7,020 $ 26,003 $ 26,297 $ 4,159 Agriculture 35,013 36,267 8,136 98,392 104,350 8,234 Commercial non-real estate 34,227 37,737 8,601 21,331 21,777 6,062 Residential real estate 5,426 5,923 2,115 3,829 4,311 1,795 Consumer 125 133 36 207 214 97 Total impaired loans with an allowance recorded 135,410 141,888 25,908 149,762 156,949 20,347 With no allowance recorded: Commercial real estate 72,060 110,873 — 28,272 66,631 — Agriculture 312,866 331,126 — 231,087 255,308 — Commercial non-real estate 59,250 67,488 — 21,579 31,414 — Residential real estate 5,475 7,870 — 3,290 5,454 — Consumer 2 110 — 1 108 — Total impaired loans with no allowance recorded 449,653 517,467 — 284,229 358,915 — Total impaired loans $ 585,063 $ 659,355 $ 25,908 $ 433,991 $ 515,864 $ 20,347 The following table presents the average recorded investment on impaired loans and interest income recognized on impaired loans for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status (dollars in thousands) Commercial real estate $ 112,623 $ 1,287 $ 34,475 $ 345 $ 93,174 $ 3,666 $ 36,616 $ 697 Agriculture 369,598 4,784 151,021 2,203 356,225 13,301 146,423 3,202 Commercial non-real estate 97,672 1,531 22,556 312 79,418 4,401 22,731 678 Residential real estate 10,904 127 6,724 93 9,642 393 6,711 182 Consumer 139 3 237 6 162 4 212 11 Total $ 590,936 $ 7,732 $ 215,013 $ 2,959 $ 538,621 $ 21,765 $ 212,693 $ 4,770 The following table provides purchased credit impaired loans at March 31, 2020 and September 30, 2019. March 31, 2020 September 30, 2019 Outstanding Balance ¹ Recorded Investment ² Carrying Value ³ Outstanding Balance ¹ Recorded Investment ² Carrying Value ³ (dollars in thousands) Commercial real estate $ 88,443 $ 21,611 $ 21,502 $ 90,295 $ 22,124 $ 21,965 Agriculture 4,259 2,970 2,970 4,462 2,756 2,491 Commercial non-real estate 7,072 178 149 7,190 221 192 Residential real estate 32,947 28,263 27,769 35,413 30,280 30,168 Consumer 441 383 362 493 438 438 Total lending $ 133,162 $ 53,405 $ 52,752 $ 137,853 $ 55,819 $ 55,254 1 Represents the legal balance of ASC 310-30 loans. 2 Represents the book balance of ASC 310-30 loans. 3 Represents the book balance of ASC 310-30 loans net of the related allowance for loan and lease losses.
Summary of troubled debt restructurings on accruing and nonaccrual loans	The following table presents the recorded value of the Company’s TDR balances as of March 31, 2020 and September 30, 2019. March 31, 2020 September 30, 2019 Accruing Nonaccrual Accruing Nonaccrual (dollars in thousands) Commercial real estate $ 19,843 $ 3,088 $ 17,145 $ 904 Agriculture 11,838 20,357 22,929 24,762 Commercial non-real estate 9,402 4,465 4,398 4,257 Residential real estate 294 92 263 102 Consumer 5 40 107 48 Total $ 41,382 $ 28,042 $ 44,842 $ 30,073 TDRs are generally restructured through either a rate modification, term extension, payment modification or due to a bankruptcy. The following table presents a summary of all accruing loans restructured in TDRs for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Recorded Investment Recorded Investment Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Commercial real estate 1 $ 2,879 $ 2,879 — $ — $ — 1 $ 2,879 $ 2,879 — $ — $ — Agriculture 2 993 993 — — — 2 993 993 — — — Commercial non-real estate 2 3,952 3,952 — — — 4 5,096 5,096 — — — Residential real estate 1 50 50 — — — 1 50 50 — — — Consumer — — — — — — — — — 1 89 89 Total accruing 6 $ 7,874 $ 7,874 — $ — $ — 8 $ 9,018 $ 9,018 1 $ 89 $ 89 Change in recorded investment due to principal paydown at time of modification — $ — $ — — $ — $ — — $ — $ — — $ — $ — Change in recorded investment due to chargeoffs at time of modification — — — — — — — — — — — — The following table presents a summary of all nonaccruing loans restructured in TDRs for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Recorded Investment Recorded Investment Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Commercial real estate — $ — $ — — $ — $ — 1 $ 2,216 $ 2,216 — $ — $ — Agriculture — — — — — — 10 1,455 1,455 — — — Commercial non-real estate — — — — — — 2 830 830 — — — Residential real estate — — — — — — — — — — — — Consumer — — — — — — — — — — — — Total nonaccruing — $ — $ — — $ — $ — 13 $ 4,501 $ 4,501 — $ — $ — Change in recorded investment due to principal paydown at time of modification — $ — $ — — $ — $ — — $ — $ — — $ — $ — Change in recorded investment due to chargeoffs at time of modification — — — — — — — — — — — — The following table presents loans that were modified as TDRs within the previous 12 months and for which there was a payment default for the three and six months ended March 31, 2020 and 2019, respectively. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Number of Loans Recorded Investment Number of Loans Recorded Investment Number of Loans Recorded Investment Number of Loans Recorded Investment (dollars in thousands) Commercial real estate — $ — — $ — — $ — — $ — Agriculture 17 2,106 — — 19 11,180 — — Commercial non-real estate — — — — 1 2,834 — — Residential real estate — — — — — — — — Consumer — — — — — — — — Total 17 $ 2,106 — $ — 20 $ 14,014 — $ —

Allowance for Loan and Lease _2

Allowance for Loan and Lease Losses (Tables)	6 Months Ended
	Mar. 31, 2020
Receivables [Abstract]
Summary of allowances for loan and lease losses	The following tables present the Company’s allowance for loan and lease losses roll forward for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, 2020 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Beginning balance, January 1, 2020 $ 17,462 $ 32,029 $ 17,389 $ 4,620 $ 288 $ 993 $ 72,781 Charge-offs (1,417) (4,522) (3,577) (118) (25) (707) (10,366) Recoveries 114 1,305 59 147 28 87 1,740 Provision 48,285 714 17,895 3,602 465 738 71,699 (Improvement) impairment of ASC 310-30 loans (30) — — 105 21 — 96 Ending balance, March 31, 2020 $ 64,414 $ 29,526 $ 31,766 $ 8,356 $ 777 $ 1,111 $ 135,950 Three Months Ended March 31, 2019 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Beginning balance, January 1, 2019 $ 16,348 $ 31,785 $ 12,093 $ 4,611 $ 430 $ 926 $ 66,193 Charge-offs (75) (5,767) (110) (310) (85) (249) (6,596) Recoveries 162 199 104 125 44 99 733 Provision (855) 7,508 962 (344) (15) 150 7,406 Impairment of ASC 310-30 loans 23 — — 244 — — 267 Ending balance, March 31, 2019 $ 15,603 $ 33,725 $ 13,049 $ 4,326 $ 374 $ 926 $ 68,003 Six Months Ended March 31, 2020 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Beginning balance, October 1, 2019 $ 16,827 $ 30,819 $ 17,567 $ 4,095 $ 427 $ 1,039 $ 70,774 Charge-offs (1,454) (9,128) (5,059) (287) (45) (1,060) (17,033) Recoveries 234 1,408 172 312 48 137 2,311 Provision 48,857 6,692 19,086 3,794 326 995 79,750 (Improvement) impairment of ASC 310-30 loans (50) (265) — 442 21 — 148 Ending balance, March 31, 2020 $ 64,414 $ 29,526 $ 31,766 $ 8,356 $ 777 $ 1,111 $ 135,950 Six Months Ended iMarch 31, 2019 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Beginning balance, October 1, 2018 $ 16,777 $ 28,121 $ 13,610 $ 4,749 $ 257 $ 1,026 $ 64,540 Charge-offs (946) (7,028) (1,471) (642) (334) (394) (10,815) Recoveries 259 357 228 287 128 131 1,390 Provision (68) 12,275 682 (369) 323 163 13,006 (Improvement) impairment of ASC 310-30 loans (419) — — 301 — — (118) Ending balance, March 31, 2019 $ 15,603 $ 33,725 $ 13,049 $ 4,326 $ 374 $ 926 $ 68,003 The following tables provide details regarding the allowance for loan and lease losses and balance by type of allowance as of March 31, 2020 and September 30, 2019. These tables are presented net of unamortized discount on acquired loans and excludes loans of $792.1 million measured at fair value, loans held for sale of $4.3 million, and guaranteed loans of $138.0 million for March 31, 2020 and loans measured at fair value of $813.0 million, loans held for sale of $7.4 million, and guaranteed loans of $145.9 million for September 30, 2019. As of March 31, 2020 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Allowance for loan and lease losses Individually evaluated for impairment $ 7,020 $ 8,136 $ 8,601 $ 2,115 $ 36 $ — $ 25,908 Collectively evaluated for impairment 57,285 21,390 23,136 5,747 720 1,111 109,389 ASC 310-30 loans 109 — 29 494 21 — 653 Total allowance $ 64,414 $ 29,526 $ 31,766 $ 8,356 $ 777 $ 1,111 $ 135,950 Financing Receivables Individually evaluated for impairment $ 132,679 $ 347,879 $ 93,477 $ 10,901 $ 127 $ — $ 585,063 Collectively evaluated for impairment 4,486,167 1,365,625 1,415,903 774,083 52,001 39,908 8,133,687 ASC 310-30 loans 21,611 2,970 178 28,263 383 — 53,405 Loans Outstanding $ 4,640,457 $ 1,716,474 $ 1,509,558 $ 813,247 $ 52,511 $ 39,908 $ 8,772,155 As of September 30, 2019 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Allowance for loan and lease losses Individually evaluated for impairment $ 4,159 $ 8,234 $ 6,062 $ 1,795 $ 97 $ — $ 20,347 Collectively evaluated for impairment 12,509 22,320 11,476 2,188 330 1,039 49,862 ASC 310-30 loans 159 265 29 112 — — 565 Total allowance $ 16,827 $ 30,819 $ 17,567 $ 4,095 $ 427 $ 1,039 $ 70,774 Financing Receivables Individually evaluated for impairment $ 54,275 $ 329,479 $ 42,910 $ 7,119 $ 208 $ — $ 433,991 Collectively evaluated for impairment 4,418,611 1,501,164 1,480,949 763,645 51,112 47,541 8,263,022 ASC 310-30 loans 22,124 2,756 221 30,280 438 — 55,819 Loans Outstanding $ 4,495,010 $ 1,833,399 $ 1,524,080 $ 801,044 $ 51,758 $ 47,541 $ 8,752,832

Accounting for Certain Loans _2

Accounting for Certain Loans Acquired with Deteriorated Credit Quality (Tables)	6 Months Ended
	Mar. 31, 2020
Receivables [Abstract]
Schedule of troubled debt restructurings	The re-assessment of purchased credit impaired loans resulted in the following changes in the accretable yield during the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 (dollars in thousands) Balance, beginning of period $ 21,130 $ 35,493 $ 26,047 $ 34,973 Accretion (1,753) (2,188) (3,693) (4,343) Reclassification (to) from nonaccretable difference (37) 375 (3,014) 3,050 Balance, end of period $ 19,340 $ 33,680 $ 19,340 $ 33,680
Schedule of impaired loans	The following table presents the Company’s impaired loans. This table excludes purchased credit impaired loans and loans measured at fair value with changes in fair value reported in earnings of $792.1 million at March 31, 2020 and $813.0 million at September 30, 2019. March 31, 2020 September 30, 2019 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance Related Allowance (dollars in thousands) Impaired loans: With an allowance recorded: Commercial real estate $ 60,619 $ 61,828 $ 7,020 $ 26,003 $ 26,297 $ 4,159 Agriculture 35,013 36,267 8,136 98,392 104,350 8,234 Commercial non-real estate 34,227 37,737 8,601 21,331 21,777 6,062 Residential real estate 5,426 5,923 2,115 3,829 4,311 1,795 Consumer 125 133 36 207 214 97 Total impaired loans with an allowance recorded 135,410 141,888 25,908 149,762 156,949 20,347 With no allowance recorded: Commercial real estate 72,060 110,873 — 28,272 66,631 — Agriculture 312,866 331,126 — 231,087 255,308 — Commercial non-real estate 59,250 67,488 — 21,579 31,414 — Residential real estate 5,475 7,870 — 3,290 5,454 — Consumer 2 110 — 1 108 — Total impaired loans with no allowance recorded 449,653 517,467 — 284,229 358,915 — Total impaired loans $ 585,063 $ 659,355 $ 25,908 $ 433,991 $ 515,864 $ 20,347 The following table presents the average recorded investment on impaired loans and interest income recognized on impaired loans for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status (dollars in thousands) Commercial real estate $ 112,623 $ 1,287 $ 34,475 $ 345 $ 93,174 $ 3,666 $ 36,616 $ 697 Agriculture 369,598 4,784 151,021 2,203 356,225 13,301 146,423 3,202 Commercial non-real estate 97,672 1,531 22,556 312 79,418 4,401 22,731 678 Residential real estate 10,904 127 6,724 93 9,642 393 6,711 182 Consumer 139 3 237 6 162 4 212 11 Total $ 590,936 $ 7,732 $ 215,013 $ 2,959 $ 538,621 $ 21,765 $ 212,693 $ 4,770 The following table provides purchased credit impaired loans at March 31, 2020 and September 30, 2019. March 31, 2020 September 30, 2019 Outstanding Balance ¹ Recorded Investment ² Carrying Value ³ Outstanding Balance ¹ Recorded Investment ² Carrying Value ³ (dollars in thousands) Commercial real estate $ 88,443 $ 21,611 $ 21,502 $ 90,295 $ 22,124 $ 21,965 Agriculture 4,259 2,970 2,970 4,462 2,756 2,491 Commercial non-real estate 7,072 178 149 7,190 221 192 Residential real estate 32,947 28,263 27,769 35,413 30,280 30,168 Consumer 441 383 362 493 438 438 Total lending $ 133,162 $ 53,405 $ 52,752 $ 137,853 $ 55,819 $ 55,254 1 Represents the legal balance of ASC 310-30 loans. 2 Represents the book balance of ASC 310-30 loans. 3 Represents the book balance of ASC 310-30 loans net of the related allowance for loan and lease losses.

FDIC Indemnification Asset (Tab

FDIC Indemnification Asset (Tables)	6 Months Ended
	Mar. 31, 2020
Banking and Thrift [Abstract]
Summary of FDIC indemnification asset activity	The following table represents a summary of the activity related to the FDIC indemnification asset for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 (dollars in thousands) Balance, beginning of period $ 832 $ 1,950 $ 1,079 $ 2,502 Amortization (390) (360) (641) (853) Changes in expected reimbursements from FDIC for changes in expected credit losses — (13) — (13) Changes in reimbursable expenses — (16) — (41) Payments (reimbursements) of covered losses to (from) the FDIC 39 (9) 43 (43) Balance, end of period $ 481 $ 1,552 $ 481 $ 1,552

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	6 Months Ended
	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of derivative positions, notional amounts and estimated fair values	The following table presents the notional amounts and gross fair values of all derivative assets and liabilities held by the Company as of March 31, 2020 and September 30, 2019. March 31, 2020 September 30, 2019 Notional Amount Gross Asset Gross Liability Notional Amount Gross Asset Gross Liability (dollars in thousands) Derivatives not designated as hedging instruments: Interest rate swaps Financial institution counterparties $ 1,279,918 $ — $ (68,412) $ 1,259,765 $ 35 $ (38,755) Customer counterparties 574,453 83,802 — 499,643 48,652 — Interest rate caps Financial institution counterparties 3,438 4 — 100 2 — Customer counterparties 3,438 — (4) 100 — (2) Risk participation agreements 78,194 — (593) 56,833 — (58) Mortgage loan commitments 170,012 636 — 56,665 — (11) Mortgage loan forward sale contracts 166,683 — (636) 61,872 11 — Total $ 2,276,136 $ 84,442 $ (69,645) $ 1,934,978 $ 48,700 $ (38,826)
Summary of offsetting assets	The following tables provide information on the Company's netting adjustments as of March 31, 2020 and September 30, 2019. Gross Fair Value Fair Value Offset Amount Cash Collateral Net Amount Presented on the Consolidated Balance Sheet (dollars in thousands) As of March 31, 2020 Total Derivative Assets $ 84,442 $ (6,922) $ 21,203 $ 98,723 Total Derivative Liabilities ¹ (69,645) 6,922 62,083 (640) 1 There was an additional $23.6 million of collateral held for initial margin with a Futures Clearing Merchant for clearing derivatives at March 31, 2020 and is included in other assets in the consolidated balance sheets. Gross Fair Value Fair Value Offset Amount Cash Collateral Net Amount Presented on the Consolidated Balance Sheet (dollars in thousands) As of September 30, 2019 Total Derivative Assets $ 48,700 $ (2,445) $ 12,279 $ 58,534 Total Derivative Liabilities ¹ (38,826) 2,445 36,368 (13) 1 There was an additional $18.3 million of collateral held for initial margin with a Futures Clearing Merchant for clearing derivatives at September 30, 2019 and is included in other assets in the consolidated balance sheets.
Summary of offsetting liabilities	The following tables provide information on the Company's netting adjustments as of March 31, 2020 and September 30, 2019. Gross Fair Value Fair Value Offset Amount Cash Collateral Net Amount Presented on the Consolidated Balance Sheet (dollars in thousands) As of March 31, 2020 Total Derivative Assets $ 84,442 $ (6,922) $ 21,203 $ 98,723 Total Derivative Liabilities ¹ (69,645) 6,922 62,083 (640) 1 There was an additional $23.6 million of collateral held for initial margin with a Futures Clearing Merchant for clearing derivatives at March 31, 2020 and is included in other assets in the consolidated balance sheets. Gross Fair Value Fair Value Offset Amount Cash Collateral Net Amount Presented on the Consolidated Balance Sheet (dollars in thousands) As of September 30, 2019 Total Derivative Assets $ 48,700 $ (2,445) $ 12,279 $ 58,534 Total Derivative Liabilities ¹ (38,826) 2,445 36,368 (13) 1 There was an additional $18.3 million of collateral held for initial margin with a Futures Clearing Merchant for clearing derivatives at September 30, 2019 and is included in other assets in the consolidated balance sheets.
Summary of effect of derivatives on consolidated statements of income	The effect of derivatives on the consolidated statements of income for the three and six months ended March 31, 2020 and 2019 was as follows. Amount of Loss Recognized in Consolidated Statements of Income Three Months Ended March 31, Six Months Ended March 31, Location of Loss Recognized in Consolidated Statements of Income 2020 2019 2020 2019 (dollars in thousands) Derivatives not designated as hedging instruments: Interest rate swaps and other derivatives Net realized and unrealized loss on derivatives $ (50,214) $ (11,032) $ (36,698) $ (29,348) Mortgage loan commitments Net realized and unrealized loss on derivatives 620 9 648 21 Mortgage loan forward sale contracts Net realized and unrealized loss on derivatives (620) (9) (648) (21)

Goodwill (Tables)

Goodwill (Tables)	6 Months Ended
	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of changes to the carrying amount of goodwill	The following table presents the Company's carrying amount of goodwill as of March 31, 2020 and September 30, 2019. March 31, September 30, (dollars in thousands) Balance, beginning of period $ 739,023 $ 739,023 Goodwill acquired during the period 1,539 — Goodwill impairment during the period (740,562) — Balance, end of period $ — $ 739,023

Core Deposits and Other Intan_2

Core Deposits and Other Intangibles (Tables)	6 Months Ended
	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of finite-lived intangible assets	The following table presents a summary of intangible assets subject to amortization as of March 31, 2020 and September 30, 2019. Core Deposit Intangible Brand Customer Relationships Intangible Other Total (dollars in thousands) As of March 31, 2020 Gross carrying amount $ 7,339 $ — $ 3,172 $ 538 $ 11,049 Accumulated amortization (3,933) — (122) (291) (4,346) Net intangible assets $ 3,406 $ — $ 3,050 $ 247 $ 6,703 As of September 30, 2019 Gross carrying amount $ 7,339 $ 8,464 $ — $ 538 $ 16,341 Accumulated amortization (3,518) (6,392) — (257) (10,167) Net intangible assets $ 3,821 $ 2,072 $ — $ 281 $ 6,174
Schedule of estimated amortization expense of intangible assets	Estimated amortization expense of intangible assets in subsequent fiscal years is as follows. Fiscal year Amount (dollars in thousands) Remaining in 2020 $ 538 2021 1,014 2022 929 2023 831 2024 742 2025 and thereafter 2,649 Total $ 6,703

Leases (Tables)

Leases (Tables)	6 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Summary of ROU Assets and Liabilities	The following table summarizes the ROU asset and lease liability as of March 31, 2020. March 31, 2020 (dollars in thousands) ROU asset $ 23,143 Total lease liability 24,036 Weighted average remaining lease term 6.7 years Weighted average discount rate ¹ 1.98 % 1 The Company uses its incremental borrowing rate to calculate the present value of lease payments when the interest rate implicit in the lease is not disclosed.
Supplemental Cash Flow Information	The following table presents supplemental cash flow information related to leases for the three and six months ended March 31, 2020: Three Months Ended March 31, 2020 Six Months Ended March 31, 2020 (dollars in thousands) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows paid for operating leases $ 1,416 $ 2,826 Right-of-use assets obtained in exchange for lease liabilities: Operating leases $ 5,007 $ 5,631
Remaining Minimum Lease Payments	The following table presents a maturity analysis of the Company's operating lease liability as of March 31, 2020. Fiscal year Amount (dollars in thousands) Remaining in 2020 $ 2,832 2021 4,741 2022 4,049 2023 3,580 2024 3,072 2025 and thereafter 7,500 Total undiscounted lease payments 25,774 Less: Amounts representing interest (1,738) Lease liability $ 24,036

Securities Sold Under Agreeme_2

Securities Sold Under Agreements to Repurchase (Tables)	6 Months Ended
	Mar. 31, 2020
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Schedule of repurchases agreements	The following tables present the gross obligation by the class of collateral pledged and the remaining contractual maturity of the agreements at March 31, 2020 and September 30, 2019. March 31, 2020 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater than 90 Days Total (dollars in thousands) Repurchase agreements Mortgage-backed securities $ 64,809 $ — $ — $ — $ 64,809 Total repurchase agreements $ 64,809 $ — $ — $ — $ 64,809 September 30, 2019 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater than 90 Days Total (dollars in thousands) Repurchase agreements Mortgage-backed securities $ 68,992 $ — $ — $ — $ 68,992 Total repurchase agreements $ 68,992 $ — $ — $ — $ 68,992

FHLB Advances and Other Borro_2

FHLB Advances and Other Borrowings (Tables)	6 Months Ended
	Mar. 31, 2020
Federal Home Loan Banks [Abstract]
Schedule of FHLB advances and other borrowings	FHLB advances and other borrowings consist of the following at March 31, 2020 and September 30, 2019. March 31, September 30, (dollars in thousands) Short-term borrowings: Notes payable to FHLB, interest rates from 0.37% to 0.74%, maturing in April 2020 and May 2020 $ 400,000 $ — FHLB fed funds advance, interest rate of 0.35%, matured in April 2020 75,000 15,000 Long-term borrowings: Notes payable to FHLB, interest rates from 2.36% to 3.66% and maturity dates from March 2021 to September 2024 collateralized by real estate loans, with various call dates at the option of the FHLB 325,000 325,000 Total $ 800,000 $ 340,000
Schedule of FHLB advances and other borrowings by maturity date	As of March 31, 2020, FHLB advances and other borrowings are due or callable (whichever is earlier) in subsequent fiscal years as follows. Fiscal year Amount (dollars in thousands) Remaining in 2020 $ 475,000 2021 120,000 2022 60,000 2023 85,000 2024 60,000 2025 and thereafter — Total $ 800,000

Subordinated Debentures and S_2

Subordinated Debentures and Subordinated Notes Payable (Tables)	6 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Summary of subordinated debentures and subordinated notes payable	Subordinated debentures and subordinated notes payable are summarized as follows. March 31, 2020 September 30, 2019 Amount Outstanding Common Shares Held in Other Assets Amount Outstanding Common Shares Held in Other Assets (dollars in thousands) Junior subordinated debentures payable to non-consolidated trusts GW Statutory Trust IV, variable rate of 2.85%, plus 3 month LIBOR $ 23,093 $ 693 $ 23,093 $ 693 GW Statutory Trust VI, variable rate of 1.48%, plus 3 month LIBOR 30,928 928 30,928 928 SSB Trust II, variable rate of 1.85%, plus 3 month LIBOR 2,062 62 2,062 62 HF Capital Trust III, variable rate of 3.35%, plus 3 month LIBOR 5,155 155 5,155 155 HF Capital Trust IV, variable rate of 3.10%, plus 3 month LIBOR 7,217 217 7,217 217 HF Capital Trust V, variable rate of 1.83%, plus 3 month LIBOR 5,310 310 5,310 310 HF Capital Trust VI, variable rate of 1.65%, plus 3 month LIBOR 2,155 155 2,155 155 Total junior subordinated debentures payable 75,920 $ 2,520 75,920 $ 2,520 Less: fair value adjustment ¹ (2,155) (2,223) Total junior subordinated debentures payable, net of fair value adjustment 73,765 73,697 Subordinated notes payable Fixed to floating rate, 4.875% per annum 35,000 35,000 Less: unamortized debt issuance costs (25) (61) Total subordinated notes payable 34,975 34,939 Total subordinated debentures and subordinated notes payable $ 108,740 $ 108,636 1 Adjustment reflects the fair value adjustments related to the junior subordinated deferrable interest debentures assumed as part of the HF Financial acquisition.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Summary of restricted share and performance-based stock award activity	The following is a summary of the Plans’ restricted share and performance-based stock award activity as of March 31, 2020 and September 30, 2019. The number of performance shares granted in the following table are reflected at the amount of achievement of the pre-established targets. March 31, 2020 September 30, 2019 Common Weighted-Average Grant Date Fair Value Common Weighted-Average Grant Date Fair Value Restricted Shares Restricted shares, beginning of fiscal year 190,805 $ 37.20 163,287 $ 37.86 Granted 134,185 32.34 106,753 37.27 Vested (83,909) 38.61 (76,210) 38.64 Forfeited (3,109) 36.61 (3,025) 38.67 Canceled — — — — Restricted shares, end of period 237,972 $ 33.97 190,805 $ 37.20 Vested, but not issuable at end of period 62,992 $ 33.98 50,770 $ 33.88 Performance Shares Performance shares, beginning of fiscal year 173,332 $ 38.50 175,196 $ 36.29 Granted (48,753) (49.22) 60,583 32.77 Vested (54,861) 39.43 (59,937) 30.79 Forfeited (3,732) 38.14 (2,510) 39.25 Canceled — — — — Performance shares, end of period 65,986 $ 34.61 173,332 $ 38.50 Vested, but not issuable at end of period 5,612 $ 18.00 5,612 $ 18.00

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of fair value measurements of assets and liabilities	The following table presents the fair value measurements of assets and liabilities recognized in the accompanying consolidated balance sheets measured at fair value on a recurring basis and the level within the fair value hierarchy in which the fair value measurements fall at March 31, 2020 and September 30, 2019. Fair Value Level 1 Level 2 Level 3 (dollars in thousands) As of March 31, 2020 U.S. Treasury securities $ 70,583 $ 70,583 $ — $ — Mortgage-backed securities 1,857,392 — 1,857,392 — States and political subdivision securities 61,001 — 57,015 3,986 Other 1,051 — 1,051 — Total securities available for sale $ 1,990,027 $ 70,583 $ 1,915,458 $ 3,986 Derivatives-assets $ 98,723 $ — $ 98,723 $ — Derivatives-liabilities 640 — 640 — Fair value loans 792,117 — 792,117 — Loan servicing rights 1,863 — — 1,863 As of September 30, 2019 U.S. Treasury securities $ 94,745 $ 94,745 $ — $ — Mortgage-backed securities 1,620,903 — 1,620,903 — States and political subdivision securities 66,523 — 62,403 4,120 Other 1,037 — 1,037 — Total securities available for sale $ 1,783,208 $ 94,745 $ 1,684,343 $ 4,120 Derivatives-assets $ 58,534 $ — $ 58,534 $ — Derivatives-liabilities 13 — 13 — Fair value loans 812,991 — 812,991 — Loan servicing rights 2,255 — — 2,255
Schedule of changes in Level 3 financial instruments	The following table presents the changes in Level 3 assets and liabilities measured at fair value on a recurring basis for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 (dollars in thousands) Other securities available for sale Balance, beginning of period $ 3,986 $ 961 $ 4,120 $ 970 Additions — 350 — 350 Principal paydown — — (134) (9) Balance, end of period $ 3,986 $ 1,311 $ 3,986 $ 1,311 Loan servicing rights Balance, beginning of period $ 2,054 $ 2,862 $ 2,255 $ 3,087 Realized and unrealized loss ¹ (191) (188) (392) (413) Balance, end of period $ 1,863 $ 2,674 $ 1,863 $ 2,674 1 Realized and unrealized loss related to loan servicing rights are reported as a component of mortgage banking income, net on the consolidated statements of income.
Summary of mortgage loans held-for-sale, fair value measurement	The following table presents the fair value measurement of assets and liabilities measured at fair value on a nonrecurring basis and the level within the fair value hierarchy in which the fair value measurements fall at March 31, 2020 and September 30, 2019. Fair Value Level 1 Level 2 Level 3 (dollars in thousands) As of March 31, 2020 Other repossessed property $ 21,486 $ — $ — $ 21,486 Impaired loans 559,155 — — 559,155 Mortgage loans held for sale, at lower of cost or fair value 4,342 — 4,342 — Property held for sale 706 — — 706 As of September 30, 2019 Other repossessed property $ 34,721 $ — $ — $ 34,721 Impaired loans 413,644 — — 413,644 Mortgage loans held for sale, at lower of cost or fair value 7,351 — 7,351 — Property held for sale 2,757 — — 2,757
Summary of valuation techniques and significant unobservable inputs used to measure Level 3 fair value measurements	The valuation techniques and significant unobservable inputs used to measure Level 3 fair value measurements at March 31, 2020 were as follows. Fair Value of Assets / (Liabilities) at March 31, 2020 Valuation Unobservable Range Weighted (dollars in thousands) Other repossessed property $ 21,486 Appraisal value Property specific adjustment N/A N/A Impaired loans 559,155 Appraisal value Property specific adjustment N/A N/A Property held for sale 706 Appraisal value Property specific adjustment N/A N/A
Schedule of fair values for balance sheet instruments	Fair values for on-balance sheet instruments as of March 31, 2020 and September 30, 2019 are as follows. March 31, 2020 September 30, 2019 Level in Fair Value Hierarchy Carrying Amount Fair Carrying Amount Fair (dollars in thousands) Assets Cash and cash equivalents Level 1 $ 347,486 $ 347,486 $ 243,474 $ 243,474 Loans, net, excluding fair valued loans, loans held for sale and impaired loans ¹ Level 3 8,337,681 8,498,042 8,472,777 8,533,612 Liabilities Time deposits Level 2 1,528,234 1,532,200 2,095,676 2,101,239 FHLB advances and other borrowings Level 2 800,000 818,669 340,000 351,517 Securities sold under repurchase agreements Level 2 64,809 64,809 68,992 68,992 Subordinated debentures and subordinated notes payable Level 2 108,740 97,268 108,636 101,164 1 Includes $13.7 million and $13.9 million of net deferred loan fees at March 31, 2020 and September 30, 2019, respectively, of which carrying value approximates fair value.

Earnings per Share (Tables)

Earnings per Share (Tables)	6 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Schedule of basic and diluted earnings per share	The following information was used in the computation of basic and diluted earnings per share (EPS) for the three and six months ended March 31, 2020 and 2019. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 (dollars in thousands, except per share data) Net income $ (740,618) $ 44,511 $ (697,344) $ 90,297 Weighted average common shares outstanding 55,906,002 56,994,817 56,141,816 57,484,838 Dilutive effect of stock based compensation — 79,857 — 72,146 Weighted average common shares outstanding for diluted earnings per share calculation 55,906,002 57,074,674 56,141,816 57,556,984 Basic earnings per share $ (13.25) $ 0.78 $ (12.42) $ 1.57 Diluted earnings per share $ (13.25) $ 0.78 $ (12.42) $ 1.57

Revenue Recognition (Tables)

Revenue Recognition (Tables)	6 Months Ended
	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Disaggregation of Noninterest Income	The following table presents total noninterest income segregated between contracts with customers within the scope of ASC Topic 606 and those within the scope of other GAAP Topics. The following additionally presents revenues from customers that are included within noninterest income. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 (dollars in thousands) Noninterest income Service charges and other fees $ 9,188 $ 10,209 $ 20,597 $ 21,897 Wealth management fees 3,122 2,117 6,086 4,358 Other 664 1,118 1,332 1,700 Noninterest income from contracts with customers within the scope of ASC Topic 606 12,974 13,444 28,015 27,955 Noninterest income within the scope of other GAAP Topics ¹ (13,057) 4,779 (12,365) 6,988 Total noninterest income $ (83) $ 18,223 $ 15,650 $ 34,943 1 The Company presents out of scope noninterest income for the purpose of reconciling noninterest income amounts within the scope of ASC Topic 606 to noninterest income amounts presented on the Company's consolidated statements of income.

Acquisition Activity (Tables)

Acquisition Activity (Tables)	6 Months Ended
	Mar. 31, 2020
Business Combinations [Abstract]
Schedule of assets acquired and liabilities assumed	The following table summarizes the consideration paid and the allocation of the purchase price to net assets as of the acquisition date. Amount (dollars in thousands) Total consideration paid $4,711 Customer relationship intangible $3,172 Goodwill $1,539

Nature of Operations and Summ_3

Nature of Operations and Summary of Significant Policies - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Apr. 30, 2020	Apr. 30, 2020	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Dividends Payable [Line Items]
Loans to customers under the program					$ 11,939	$ 383,665
Common stock dividends declared (in dollars per share)			$ 0.30	$ 0.25	$ 0.60	$ 0.50
Subsequent event
Dividends Payable [Line Items]
Loans to customers under the program		$ 600,000
Common stock dividends declared (in dollars per share)	$ 0.15

New Accounting Standards - Narr

New Accounting Standards - Narrative (Details) - USD ($) $ in Thousands		Mar. 31, 2020	Oct. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
ROU asset		$ 23,143
Total lease liability		$ 24,036
Cumulative effect adjustment related to ASU adoption	[1]		$ (182)
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment related to ASU adoption	[1]		(182)
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
ROU asset			19,900
Total lease liability			20,900
ASU 2016-02 | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment related to ASU adoption			$ 200
[1]	Related to the Company's adoption of ASU 2016-02 and subsequent related ASUs on October 1, 2019. See Note 2, "New Accounting Pronouncements," for additional information.

Securities Available for Sale -

Securities Available for Sale - Schedule of Amortized Cost and Fair Value of Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	$ 1,941,922	$ 1,765,284
Gross Unrealized Gains	49,665	22,421
Gross Unrealized Losses	(1,560)	(4,497)
Estimated Fair Value	1,990,027	1,783,208
U.S. Treasury securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	69,629	94,178
Gross Unrealized Gains	954	599
Gross Unrealized Losses	0	(32)
Estimated Fair Value	70,583	94,745
Mortgage-backed Securities | Government National Mortgage Association
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	566,747	501,139
Gross Unrealized Gains	11,340	3,374
Gross Unrealized Losses	(733)	(3,027)
Estimated Fair Value	577,354	501,486
Mortgage-backed Securities | Federal Home Loan Mortgage Corporation
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	556,535	463,974
Gross Unrealized Gains	15,747	8,840
Gross Unrealized Losses	(731)	(770)
Estimated Fair Value	571,551	472,044
Mortgage-backed Securities | Federal National Mortgage Association
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	386,996	322,340
Gross Unrealized Gains	15,337	5,409
Gross Unrealized Losses	(27)	(398)
Estimated Fair Value	402,306	327,351
Mortgage-backed Securities | Small Business Assistance Program
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	300,498	316,502
Gross Unrealized Gains	5,725	3,674
Gross Unrealized Losses	(42)	(154)
Estimated Fair Value	306,181	320,022
States and political subdivision securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	60,511	66,145
Gross Unrealized Gains	517	494
Gross Unrealized Losses	(27)	(116)
Estimated Fair Value	61,001	66,523
Other
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	1,006	1,006
Gross Unrealized Gains	45	31
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 1,051	$ 1,037

Securities Available for Sale_2

Securities Available for Sale - Schedule of Amortized Cost and Fair Value of Investments by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Amortized  Cost
Due in one year or less	$ 82,615	$ 58,377
Due after one year through five years	35,858	89,836
Due after five years through ten years	11,667	12,110
Due after ten years	0	0
Amortized  Cost	130,140	160,323
Estimated Fair Value
Due in one year or less	83,577	58,343
Due after one year through five years	36,102	90,601
Due after five years through ten years	11,905	12,324
Due after ten years	0	0
Estimated Fair Value	131,584	161,268
Amortized  Cost	1,941,922	1,765,284
Estimated Fair Value	1,990,027	1,783,208
Securities without contractual maturities, Amortized Cost	1,006	1,006
Securities without contractual maturities, Fair Value	1,051	1,037
Mortgage-backed securities
Estimated Fair Value
Amortized  Cost	1,810,776	1,603,955
Estimated Fair Value	$ 1,857,392	$ 1,620,903

Securities Available for Sale_3

Securities Available for Sale - Narrative (Details)	3 Months Ended		6 Months Ended
	Mar. 31, 2020USD ($)security	Mar. 31, 2019USD ($)	Mar. 31, 2020USD ($)security	Mar. 31, 2019USD ($)	Sep. 30, 2019USD ($)security
Investments, Debt and Equity Securities [Abstract]
Proceeds from sales of securities available for sale	$ 0	$ 0	$ 0	$ 97,212,000
Gross gains realized	0		0
Gross loss realized				500,000
Other than temporary impairment losses recognized in earnings	0	$ 0	0	$ 0
Securities pledged as collateral	$ 918,800,000		$ 918,800,000		$ 863,900,000
Percentage of investment portfolio in continuous loss position (as a percent)	12.00%		12.00%		36.00%
Number of securities in an unrealized loss position (securities) | security	58		58		169

Securities Available for Sale_4

Securities Available for Sale - Schedule of Gross Unrealized Losses on Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	$ 30,374	$ 94,612
12 months or more, Estimated Fair Value	217,197	543,401
Estimated Fair Value	247,571	638,013
12 months or more, Unrealized Losses	(189)	(205)
Less than 12 months, Unrealized Losses	(1,371)	(4,292)
Unrealized Losses	(1,560)	(4,497)
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	0	0
12 months or more, Estimated Fair Value	0	44,729
Estimated Fair Value	0	44,729
12 months or more, Unrealized Losses	0	0
Less than 12 months, Unrealized Losses	0	(32)
Unrealized Losses	0	(32)
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	30,374	94,612
12 months or more, Estimated Fair Value	207,955	474,979
Estimated Fair Value	238,329	569,591
12 months or more, Unrealized Losses	(189)	(205)
Less than 12 months, Unrealized Losses	(1,344)	(4,144)
Unrealized Losses	(1,533)	(4,349)
States and political subdivision securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	0	0
12 months or more, Estimated Fair Value	9,242	23,693
Estimated Fair Value	9,242	23,693
12 months or more, Unrealized Losses	0	0
Less than 12 months, Unrealized Losses	(27)	(116)
Unrealized Losses	(27)	(116)
Other
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	0	0
12 months or more, Estimated Fair Value	0	0
Estimated Fair Value	0	0
12 months or more, Unrealized Losses	0	0
Less than 12 months, Unrealized Losses	0	0
Unrealized Losses	$ 0	$ 0

Loans - Schedule of Loans Recei

Loans - Schedule of Loans Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	$ 9,717,115	$ 9,732,684
Less: Unamortized discount on acquired loans	(10,468)	(13,655)
Unearned net deferred fees and costs and loans in process	(13,352)	(12,266)
Total	9,693,295	9,706,763
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	5,222,819	5,092,410
Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	1,881,792	2,008,644
Commercial non-real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	1,699,197	1,719,956
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	820,759	812,208
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	52,640	51,925
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	$ 39,908	$ 47,541

Loans - Narrative (Details)

Loans - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans covered by a FDIC loss sharing agreement	$ 29,691			$ 29,691		$ 31,891
Loan held for sale	4,342			4,342		7,351
Loans and written loan commitments at fair value under the fair value option	792,117			792,117		812,991
Unamortized discount on acquired loans	13,700			13,700		13,900
Loans in process	400			400		1,600
Loans guaranteed by U.S. Government Agencies	8,772,155			8,772,155		8,752,832
Principal balances of residential real estate loans sold	68,400		$ 46,800	175,400	$ 100,700
Loans greater than 90 days past due and still accruing interest	2,300			2,300		11,200
Valuation adjustments made to repossessed properties	4,800		100	4,800	2,000
Specific reserves included in the allowance for loan losses for TDRs		$ 10,300		6,900
Troubled debt restructuring, commitments to lend additional funds	100			100		200
Transfers out of troubled debt restructuring status	300		$ 0	300	$ 0
Loans Guaranteed by US Government Authorities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans guaranteed by U.S. Government Agencies	$ 146,200			$ 146,200		$ 154,200

Loans - Schedule of the Company

Loans - Schedule of the Company's Nonaccrual Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans, excluding loans covered under FDIC loss-sharing arrangements	$ 210,607	$ 105,090
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans, excluding loans covered under FDIC loss-sharing arrangements	41,541	14,973
Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans, excluding loans covered under FDIC loss-sharing arrangements	143,198	77,880
Commercial non-real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans, excluding loans covered under FDIC loss-sharing arrangements	21,334	9,502
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans, excluding loans covered under FDIC loss-sharing arrangements	4,437	2,661
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans, excluding loans covered under FDIC loss-sharing arrangements	$ 97	$ 74

Loans - Schedule of the Composi

Loans - Schedule of the Composition of the Loan Portfolio by Internal Risk Rating (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	$ 8,884,834	$ 8,874,149
Loans covered by a FDIC loss sharing agreement	29,691	31,891
Total	8,914,525	8,906,040
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	7,935,831	8,066,457
Watchlist
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	365,120	375,787
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	582,276	425,685
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	1,607	6,220
Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	0	0
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	4,716,122	4,573,084
Loans covered by a FDIC loss sharing agreement	0	0
Total	4,716,122	4,573,084
Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	4,478,193	4,433,530
Commercial real estate | Watchlist
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	104,941	85,256
Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	132,937	54,242
Commercial real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	51	56
Commercial real estate | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	0	0
Agriculture
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	1,734,388	1,854,539
Loans covered by a FDIC loss sharing agreement	0	0
Total	1,734,388	1,854,539
Agriculture | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	1,157,671	1,346,436
Agriculture | Watchlist
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	229,606	179,965
Agriculture | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	345,674	322,327
Agriculture | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	1,437	5,811
Agriculture | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	0	0
Commercial non-real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	1,553,513	1,570,215
Loans covered by a FDIC loss sharing agreement	0	0
Total	1,553,513	1,570,215
Commercial non-real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	1,431,706	1,424,357
Commercial non-real estate | Watchlist
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	28,859	103,514
Commercial non-real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	92,849	42,048
Commercial non-real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	99	296
Commercial non-real estate | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	0	0
Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	788,392	777,012
Loans covered by a FDIC loss sharing agreement	29,691	31,891
Total	818,083	808,903
Residential real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	776,696	763,797
Residential real estate | Watchlist
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	986	6,297
Residential real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	10,694	6,863
Residential real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	16	55
Residential real estate | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	0	0
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	52,511	51,758
Loans covered by a FDIC loss sharing agreement	0	0
Total	52,511	51,758
Consumer | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	51,657	50,796
Consumer | Watchlist
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	728	755
Consumer | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	122	205
Consumer | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	4	2
Consumer | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	0	0
Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	39,908	47,541
Loans covered by a FDIC loss sharing agreement	0	0
Total	39,908	47,541
Other | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	39,908	47,541
Other | Watchlist
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	0	0
Other | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	0	0
Other | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	0	0
Other | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	$ 0	$ 0

Loans - Schedule of Past Due Lo

Loans - Schedule of Past Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	$ 8,884,834	$ 8,874,149
Loans covered by a FDIC loss sharing agreement	29,691	31,891
Total	8,914,525	8,906,040
Commercial real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	4,716,122	4,573,084
Loans covered by a FDIC loss sharing agreement	0	0
Total	4,716,122	4,573,084
Agriculture
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,734,388	1,854,539
Loans covered by a FDIC loss sharing agreement	0	0
Total	1,734,388	1,854,539
Commercial non-real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,553,513	1,570,215
Loans covered by a FDIC loss sharing agreement	0	0
Total	1,553,513	1,570,215
Residential real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	788,392	777,012
Loans covered by a FDIC loss sharing agreement	29,691	31,891
Total	818,083	808,903
Consumer
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	52,511	51,758
Loans covered by a FDIC loss sharing agreement	0	0
Total	52,511	51,758
Other
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	39,908	47,541
Loans covered by a FDIC loss sharing agreement	0	0
Total	39,908	47,541
Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	174,262	64,979
Loans covered by a FDIC loss sharing agreement	2,277	1,277
Total	176,539	66,256
Past Due | Commercial real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	43,159	6,632
Past Due | Agriculture
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	100,532	47,767
Past Due | Commercial non-real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	23,991	8,476
Past Due | Residential real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	6,504	1,926
Past Due | Consumer
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	76	178
Past Due | Other
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	0	0
Past Due | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	61,829	21,302
Loans covered by a FDIC loss sharing agreement	1,201	536
Total	63,030	21,838
Past Due | 30-59 Days Past Due | Commercial real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	25,351	3,587
Past Due | 30-59 Days Past Due | Agriculture
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	30,196	13,411
Past Due | 30-59 Days Past Due | Commercial non-real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	2,538	3,932
Past Due | 30-59 Days Past Due | Residential real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	3,702	311
Past Due | 30-59 Days Past Due | Consumer
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	42	61
Past Due | 30-59 Days Past Due | Other
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	0	0
Past Due | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	15,429	2,743
Loans covered by a FDIC loss sharing agreement	319	410
Total	15,748	3,153
Past Due | 60-89 Days Past Due | Commercial real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	4,056	570
Past Due | 60-89 Days Past Due | Agriculture
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	10,160	1,267
Past Due | 60-89 Days Past Due | Commercial non-real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	956	120
Past Due | 60-89 Days Past Due | Residential real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	252	676
Past Due | 60-89 Days Past Due | Consumer
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	5	110
Past Due | 60-89 Days Past Due | Other
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	0	0
Past Due | 90 Days or Greater Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	97,004	40,934
Loans covered by a FDIC loss sharing agreement	757	331
Total	97,761	41,265
Past Due | 90 Days or Greater Past Due | Commercial real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	13,752	2,475
Past Due | 90 Days or Greater Past Due | Agriculture
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	60,176	33,089
Past Due | 90 Days or Greater Past Due | Commercial non-real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	20,497	4,424
Past Due | 90 Days or Greater Past Due | Residential real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	2,550	939
Past Due | 90 Days or Greater Past Due | Consumer
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	29	7
Past Due | 90 Days or Greater Past Due | Other
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	0	0
Current
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	8,710,572	8,809,170
Loans covered by a FDIC loss sharing agreement	27,414	30,614
Total	8,737,986	8,839,784
Current | Commercial real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	4,672,963	4,566,452
Current | Agriculture
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,633,856	1,806,772
Current | Commercial non-real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,529,522	1,561,739
Current | Residential real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	781,888	775,086
Current | Consumer
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	52,435	51,580
Current | Other
Financing Receivable, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	$ 39,908	$ 47,541

Loans - Schedule of Impaired Lo

Loans - Schedule of Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2019
With an allowance recorded:
Recorded Investment	$ 135,410				$ 149,762
Unpaid Principal Balance	141,888				156,949
Related Allowance	25,908				20,347
With no allowance recorded:
Recorded Investment	449,653				284,229
Unpaid Principal Balance	517,467				358,915
Total Recorded Investment, Impaired Loans	585,063				433,991
Total Unpaid Principal Balance, Impaired Loans	659,355				515,864
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	590,936	$ 538,621	$ 215,013	$ 212,693
Interest Income Recognized While on Impaired Status	7,732	21,765	2,959	4,770
Commercial real estate
With an allowance recorded:
Recorded Investment	60,619				26,003
Unpaid Principal Balance	61,828				26,297
Related Allowance	7,020				4,159
With no allowance recorded:
Recorded Investment	72,060				28,272
Unpaid Principal Balance	110,873				66,631
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	112,623	93,174	34,475	36,616
Interest Income Recognized While on Impaired Status	1,287	3,666	345	697
Agriculture
With an allowance recorded:
Recorded Investment	35,013				98,392
Unpaid Principal Balance	36,267				104,350
Related Allowance	8,136				8,234
With no allowance recorded:
Recorded Investment	312,866				231,087
Unpaid Principal Balance	331,126				255,308
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	369,598	356,225	151,021	146,423
Interest Income Recognized While on Impaired Status	4,784	13,301	2,203	3,202
Commercial non-real estate
With an allowance recorded:
Recorded Investment	34,227				21,331
Unpaid Principal Balance	37,737				21,777
Related Allowance	8,601				6,062
With no allowance recorded:
Recorded Investment	59,250				21,579
Unpaid Principal Balance	67,488				31,414
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	97,672	79,418	22,556	22,731
Interest Income Recognized While on Impaired Status	1,531	4,401	312	678
Residential real estate
With an allowance recorded:
Recorded Investment	5,426				3,829
Unpaid Principal Balance	5,923				4,311
Related Allowance	2,115				1,795
With no allowance recorded:
Recorded Investment	5,475				3,290
Unpaid Principal Balance	7,870				5,454
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	10,904	9,642	6,724	6,711
Interest Income Recognized While on Impaired Status	127	393	93	182
Consumer
With an allowance recorded:
Recorded Investment	125				207
Unpaid Principal Balance	133				214
Related Allowance	36				97
With no allowance recorded:
Recorded Investment	2				1
Unpaid Principal Balance	110				$ 108
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	139	162	237	212
Interest Income Recognized While on Impaired Status	$ 3	$ 4	$ 6	$ 11

Loans - Summary of Troubled Deb

Loans - Summary of Troubled Debt Restructurings on Accruing and Nonaccrual Financing Receivables (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)contract	Dec. 31, 2019USD ($)contract	Mar. 31, 2019USD ($)contract	Dec. 31, 2018USD ($)contract	Sep. 30, 2019USD ($)
Accruing
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded value of TDR balance	$ 41,382				$ 44,842
Financing receivable, modifications, number of contracts | contract	6	8	0	1
Financing receivable, modifications, pre-modification recorded investment	$ 7,874	$ 9,018	$ 0	$ 89
Financing receivable, modifications, post-modification recorded investment	$ 7,874	$ 9,018	$ 0	$ 89
Change in recorded investment due to principal paydown at time of modification, number of contracts | contract	0	0	0	0
Change in recorded investment due to principal paydown at time of modification, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Change in recorded investment due to principal paydown at time of modification, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Change in recorded investment due to chargeoffs at time of modification, number of contracts | contract	0	0	0	0
Change in recorded investment due to chargeoffs at time of modification, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Change in recorded investment due to chargeoffs at time of modification, post-modification recorded investment	0	$ 0	$ 0	$ 0
Nonaccrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded value of TDR balance	$ 28,042				30,073
Financing receivable, modifications, number of contracts | contract	0	13	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 4,501	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 4,501	$ 0	$ 0
Change in recorded investment due to principal paydown at time of modification, number of contracts | contract	0	0	0	0
Change in recorded investment due to principal paydown at time of modification, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Change in recorded investment due to principal paydown at time of modification, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Change in recorded investment due to chargeoffs at time of modification, number of contracts | contract	0	0	0	0
Change in recorded investment due to chargeoffs at time of modification, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Change in recorded investment due to chargeoffs at time of modification, post-modification recorded investment	0	$ 0	$ 0	$ 0
Commercial real estate | Accruing
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded value of TDR balance	$ 19,843				17,145
Financing receivable, modifications, number of contracts | contract	1	1	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 2,879	$ 2,879	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	2,879	$ 2,879	$ 0	$ 0
Commercial real estate | Nonaccrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded value of TDR balance	$ 3,088				904
Financing receivable, modifications, number of contracts | contract	0	1	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 2,216	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	0	$ 2,216	$ 0	$ 0
Agriculture | Accruing
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded value of TDR balance	$ 11,838				22,929
Financing receivable, modifications, number of contracts | contract	2	2	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 993	$ 993	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	993	$ 993	$ 0	$ 0
Agriculture | Nonaccrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded value of TDR balance	$ 20,357				24,762
Financing receivable, modifications, number of contracts | contract	0	10	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 1,455	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	0	$ 1,455	$ 0	$ 0
Commercial non-real estate | Accruing
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded value of TDR balance	$ 9,402				4,398
Financing receivable, modifications, number of contracts | contract	2	4	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 3,952	$ 5,096	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	3,952	$ 5,096	$ 0	$ 0
Commercial non-real estate | Nonaccrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded value of TDR balance	$ 4,465				4,257
Financing receivable, modifications, number of contracts | contract	0	2	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 830	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	0	$ 830	$ 0	$ 0
Residential real estate | Accruing
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded value of TDR balance	$ 294				263
Financing receivable, modifications, number of contracts | contract	1	1	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 50	$ 50	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	50	$ 50	$ 0	$ 0
Residential real estate | Nonaccrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded value of TDR balance	$ 92				102
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	0	$ 0	$ 0	$ 0
Consumer | Accruing
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded value of TDR balance	$ 5				107
Financing receivable, modifications, number of contracts | contract	0	0	0	1
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 89
Financing receivable, modifications, post-modification recorded investment	0	$ 0	$ 0	$ 89
Consumer | Nonaccrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded value of TDR balance	$ 40				$ 48
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0

Loans - Subsequent Defaults on

Loans - Subsequent Defaults on Modified Loans (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020USD ($)contract	Mar. 31, 2019USD ($)contract	Mar. 31, 2020USD ($)contract	Mar. 31, 2019USD ($)contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | contract	17	0	20	0
Recorded Investment | $	$ 2,106	$ 0	$ 14,014	$ 0
Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | contract	0	0	0	0
Recorded Investment | $	$ 0	$ 0	$ 0	$ 0
Agriculture
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | contract	17	0	19	0
Recorded Investment | $	$ 2,106	$ 0	$ 11,180	$ 0
Commercial non-real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | contract	0	0	1	0
Recorded Investment | $	$ 0	$ 0	$ 2,834	$ 0
Residential real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | contract	0	0	0	0
Recorded Investment | $	$ 0	$ 0	$ 0	$ 0
Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | contract	0	0	0	0
Recorded Investment | $	$ 0	$ 0	$ 0	$ 0

Allowance for Loan and Lease _3

Allowance for Loan and Lease Losses - Summary of Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan losses, beginning balance	$ 72,781	$ 66,193	$ 70,774	$ 64,540
Charge-offs	(10,366)	(6,596)	(17,033)	(10,815)
Recoveries	1,740	733	2,311	1,390
Provision	71,699	7,406	79,750	13,006
Allowance for loan losses, ending balance	135,950	68,003	135,950	68,003
Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan losses, beginning balance			600
(Improvement) impairment of ASC 310-30 loans	96	267	148	(118)
Allowance for loan losses, ending balance	700		700
Commercial real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan losses, beginning balance	17,462	16,348	16,827	16,777
Charge-offs	(1,417)	(75)	(1,454)	(946)
Recoveries	114	162	234	259
Provision	48,285	(855)	48,857	(68)
Allowance for loan losses, ending balance	64,414	15,603	64,414	15,603
Commercial real estate | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Loss [Roll Forward]
(Improvement) impairment of ASC 310-30 loans	(30)	23	(50)	(419)
Agriculture
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan losses, beginning balance	32,029	31,785	30,819	28,121
Charge-offs	(4,522)	(5,767)	(9,128)	(7,028)
Recoveries	1,305	199	1,408	357
Provision	714	7,508	6,692	12,275
Allowance for loan losses, ending balance	29,526	33,725	29,526	33,725
Agriculture | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Loss [Roll Forward]
(Improvement) impairment of ASC 310-30 loans	0	0	(265)	0
Commercial non-real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan losses, beginning balance	17,389	12,093	17,567	13,610
Charge-offs	(3,577)	(110)	(5,059)	(1,471)
Recoveries	59	104	172	228
Provision	17,895	962	19,086	682
Allowance for loan losses, ending balance	31,766	13,049	31,766	13,049
Commercial non-real estate | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Loss [Roll Forward]
(Improvement) impairment of ASC 310-30 loans	0	0	0	0
Residential real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan losses, beginning balance	4,620	4,611	4,095	4,749
Charge-offs	(118)	(310)	(287)	(642)
Recoveries	147	125	312	287
Provision	3,602	(344)	3,794	(369)
Allowance for loan losses, ending balance	8,356	4,326	8,356	4,326
Residential real estate | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Loss [Roll Forward]
(Improvement) impairment of ASC 310-30 loans	105	244	442	301
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan losses, beginning balance	288	430	427	257
Charge-offs	(25)	(85)	(45)	(334)
Recoveries	28	44	48	128
Provision	465	(15)	326	323
Allowance for loan losses, ending balance	777	374	777	374
Consumer | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Loss [Roll Forward]
(Improvement) impairment of ASC 310-30 loans	21	0	21	0
Other
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan losses, beginning balance	993	926	1,039	1,026
Charge-offs	(707)	(249)	(1,060)	(394)
Recoveries	87	99	137	131
Provision	738	150	995	163
Allowance for loan losses, ending balance	1,111	926	1,111	926
Other | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Loss [Roll Forward]
(Improvement) impairment of ASC 310-30 loans	$ 0	$ 0	$ 0	$ 0

Allowance for Loan and Lease _4

Allowance for Loan and Lease Losses - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and written loan commitments at fair value under the fair value option	$ 792,117		$ 792,117			$ 812,991
Loan held for sale	4,342		4,342			7,351
Loans guaranteed by U.S. Government Agencies	8,772,155		8,772,155			8,752,832
Allowance for loan leases	135,950	$ 68,003	135,950	$ 68,003	$ 72,781	70,774	$ 66,193	$ 64,540
Unfunded loan commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Reserve for unfunded loan commitments	1,100		1,100			500
Receivables acquired with deteriorated credit quality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan leases	700		700			600
Net reversal of provision	96	$ 267	148	$ (118)
Loans Guaranteed by US Government Authorities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans guaranteed by U.S. Government Agencies	146,200		146,200			154,200
Loans Guaranteed by US Government Authorities | Loans and Leases with Allowance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans guaranteed by U.S. Government Agencies	$ 138,000		$ 138,000			$ 145,900

Allowance for Loan and Lease _5

Allowance for Loan and Lease Losses - Summary of Allowance for Loan Losses by Type (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018
Allowance for loan and lease losses
Individually evaluated for impairment	$ 25,908		$ 20,347
Collectively evaluated for impairment	109,389		49,862
Total allowance	135,950	$ 72,781	70,774	$ 68,003	$ 66,193	$ 64,540
Financing Receivables
Individually evaluated for impairment	585,063		433,991
Collectively evaluated for impairment	8,133,687		8,263,022
Loans Outstanding	8,772,155		8,752,832
Receivables acquired with deteriorated credit quality
Allowance for loan and lease losses
ASC 310-30 loans	653		565
Total allowance	700		600
Financing Receivables
ASC 310-30 loans	53,405		55,819
Commercial real estate
Allowance for loan and lease losses
Individually evaluated for impairment	7,020		4,159
Collectively evaluated for impairment	57,285		12,509
Total allowance	64,414	17,462	16,827	15,603	16,348	16,777
Financing Receivables
Individually evaluated for impairment	132,679		54,275
Collectively evaluated for impairment	4,486,167		4,418,611
Loans Outstanding	4,640,457		4,495,010
Commercial real estate | Receivables acquired with deteriorated credit quality
Allowance for loan and lease losses
ASC 310-30 loans	109		159
Financing Receivables
ASC 310-30 loans	21,611		22,124
Agriculture
Allowance for loan and lease losses
Individually evaluated for impairment	8,136		8,234
Collectively evaluated for impairment	21,390		22,320
Total allowance	29,526	32,029	30,819	33,725	31,785	28,121
Financing Receivables
Individually evaluated for impairment	347,879		329,479
Collectively evaluated for impairment	1,365,625		1,501,164
Loans Outstanding	1,716,474		1,833,399
Agriculture | Receivables acquired with deteriorated credit quality
Allowance for loan and lease losses
ASC 310-30 loans	0		265
Financing Receivables
ASC 310-30 loans	2,970		2,756
Commercial non-real estate
Allowance for loan and lease losses
Individually evaluated for impairment	8,601		6,062
Collectively evaluated for impairment	23,136		11,476
Total allowance	31,766	17,389	17,567	13,049	12,093	13,610
Financing Receivables
Individually evaluated for impairment	93,477		42,910
Collectively evaluated for impairment	1,415,903		1,480,949
Loans Outstanding	1,509,558		1,524,080
Commercial non-real estate | Receivables acquired with deteriorated credit quality
Allowance for loan and lease losses
ASC 310-30 loans	29		29
Financing Receivables
ASC 310-30 loans	178		221
Residential real estate
Allowance for loan and lease losses
Individually evaluated for impairment	2,115		1,795
Collectively evaluated for impairment	5,747		2,188
Total allowance	8,356	4,620	4,095	4,326	4,611	4,749
Financing Receivables
Individually evaluated for impairment	10,901		7,119
Collectively evaluated for impairment	774,083		763,645
Loans Outstanding	813,247		801,044
Residential real estate | Receivables acquired with deteriorated credit quality
Allowance for loan and lease losses
ASC 310-30 loans	494		112
Financing Receivables
ASC 310-30 loans	28,263		30,280
Consumer
Allowance for loan and lease losses
Individually evaluated for impairment	36		97
Collectively evaluated for impairment	720		330
Total allowance	777	288	427	374	430	257
Financing Receivables
Individually evaluated for impairment	127		208
Collectively evaluated for impairment	52,001		51,112
Loans Outstanding	52,511		51,758
Consumer | Receivables acquired with deteriorated credit quality
Allowance for loan and lease losses
ASC 310-30 loans	21		0
Financing Receivables
ASC 310-30 loans	383		438
Other
Allowance for loan and lease losses
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	1,111		1,039
Total allowance	1,111	$ 993	1,039	$ 926	$ 926	$ 1,026
Financing Receivables
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	39,908		47,541
Loans Outstanding	39,908		47,541
Other | Receivables acquired with deteriorated credit quality
Allowance for loan and lease losses
ASC 310-30 loans	0		0
Financing Receivables
ASC 310-30 loans	$ 0		$ 0

Accounting for Certain Loans _3

Accounting for Certain Loans Acquired with Deteriorated Credit Quality - Schedule of Troubled Debt Restructurings (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	$ 21,130	$ 35,493	$ 26,047	$ 34,973
Accretion	(1,753)	(2,188)	(3,693)	(4,343)
Reclassification (to) from nonaccretable difference	(37)	375	(3,014)	3,050
Balance at end of period	$ 19,340	$ 33,680	$ 19,340	$ 33,680

Accounting for Certain Loans _4

Accounting for Certain Loans Acquired with Deteriorated Credit Quality - Schedule of Impaired Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	$ 133,162	$ 137,853
Recorded Investment	53,405	55,819
Carrying Value	52,752	55,254
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	88,443	90,295
Recorded Investment	21,611	22,124
Carrying Value	21,502	21,965
Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	4,259	4,462
Recorded Investment	2,970	2,756
Carrying Value	2,970	2,491
Commercial non-real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	7,072	7,190
Recorded Investment	178	221
Carrying Value	149	192
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	32,947	35,413
Recorded Investment	28,263	30,280
Carrying Value	27,769	30,168
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	441	493
Recorded Investment	383	438
Carrying Value	$ 362	$ 438

FDIC Indemnification Asset - Su

FDIC Indemnification Asset - Summary of FDIC Indemnification Asset Activity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
FDIC Indemnification Asset [Roll Forward]
Balance, beginning of period	$ 832	$ 1,950	$ 1,079	$ 2,502
Amortization	(390)	(360)	(641)	(853)
Changes in expected reimbursements from FDIC for changes in expected credit losses	0	(13)	0	(13)
Changes in reimbursable expenses	0	(16)	0	(41)
Payments (reimbursements) of covered losses to (from) the FDIC	39	(9)	43	(43)
Balance, end of period	$ 481	$ 1,552	$ 481	$ 1,552

Derivative Financial Instrume_3

Derivative Financial Instruments - Schedule of Derivative Positions, Notional Amounts and Estimated Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Derivative [Line Items]
Gross Asset Fair Value	$ 84,442	$ 48,700
Gross Liability Fair Value	(69,645)	(38,826)
Not Designated as Hedging Instruments
Derivative [Line Items]
Notional Amount	2,276,136	1,934,978
Gross Asset Fair Value	84,442	48,700
Gross Liability Fair Value	(69,645)	(38,826)
Not Designated as Hedging Instruments | Interest rate swaps | Financial institution counterparties
Derivative [Line Items]
Notional Amount	1,279,918	1,259,765
Gross Asset Fair Value	0	35
Gross Liability Fair Value	(68,412)	(38,755)
Not Designated as Hedging Instruments | Interest rate swaps | Customer counterparties
Derivative [Line Items]
Notional Amount	574,453	499,643
Gross Asset Fair Value	83,802	48,652
Gross Liability Fair Value	0	0
Not Designated as Hedging Instruments | Interest rate caps | Financial institution counterparties
Derivative [Line Items]
Notional Amount	3,438	100
Gross Asset Fair Value	4	2
Gross Liability Fair Value	0	0
Not Designated as Hedging Instruments | Interest rate caps | Customer counterparties
Derivative [Line Items]
Notional Amount	3,438	100
Gross Asset Fair Value	0	0
Gross Liability Fair Value	(4)	(2)
Not Designated as Hedging Instruments | Risk participation agreements
Derivative [Line Items]
Notional Amount	78,194	56,833
Gross Asset Fair Value	0	0
Gross Liability Fair Value	(593)	(58)
Not Designated as Hedging Instruments | Mortgage loan commitments
Derivative [Line Items]
Notional Amount	170,012	56,665
Gross Asset Fair Value	636	0
Gross Liability Fair Value	0	(11)
Not Designated as Hedging Instruments | Mortgage loan forward sale contracts
Derivative [Line Items]
Notional Amount	166,683	61,872
Gross Asset Fair Value	0	11
Gross Liability Fair Value	$ (636)	$ 0

Derivative Financial Instrume_4

Derivative Financial Instruments - Summary of Offsetting Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative assets, gross amount	$ 84,442	$ 48,700
Derivative assets, fair value offset amount	(6,922)	(2,445)
Derivative assets, cash collateral	21,203	12,279
Derivative Assets	98,723	58,534
Derivative liabilities, gross amount	(69,645)	(38,826)
Derivative liabilities, fair value offset amount	6,922	2,445
Derivative liabilities, cash collateral	62,083	36,368
Derivative Liabilities	(640)	(13)
Collateral held for initial margin	$ 23,600	$ 18,300

Derivative Financial Instrume_5

Derivative Financial Instruments - Effect on the Consolidated Statement of Comprehensive Income (Details) - Noninterest income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Interest rate swaps and other derivatives
Derivative [Line Items]
Amount of Loss Recognized in Consolidated Statements of Income	$ (50,214)	$ (11,032)	$ (36,698)	$ (29,348)
Mortgage loan commitments
Derivative [Line Items]
Amount of Loss Recognized in Consolidated Statements of Income	620	9	648	21
Mortgage loan forward sale contracts
Derivative [Line Items]
Amount of Loss Recognized in Consolidated Statements of Income	$ (620)	$ (9)	$ (648)	$ (21)

The Fair Value Option for Cer_2

The Fair Value Option for Certain Loans - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Eligible item for the fair value option	$ 57,500		$ 57,500		$ 34,200
Loans greater than 90 days past due or in nonaccrual status	9,100		9,100		16,500
Unpaid principal balance greater than 90 days past due or in nonaccrual status	12,100		12,100		17,800
Net increase (decrease) in fair value of loans at fair value	35,541	$ 14,018	20,608	$ 33,234
Long-term loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total unpaid principal balance of long-term loans	734,600		734,600		$ 778,800
Total change in fair value attributable to changes in specific credit risk	10,500	(400)	12,700	800
Long-term loans | Noninterest income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net increase (decrease) in fair value of loans at fair value	$ 35,500	$ 14,000	$ 20,600	$ 33,200

Goodwill - Carrying Amount of G

Goodwill - Carrying Amount of Goodwill (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2019
Goodwill [Roll Forward]
Balance, beginning of period			$ 739,023,000	$ 739,023,000	$ 739,023,000
Goodwill acquired during the period			1,539,000		0
Goodwill impairment during the period	$ (740,600,000)	$ 0	(740,562,000)	$ 0	0
Balance, end of period	$ 0		$ 0		$ 739,023,000

Goodwill - Narrative (Details)

Goodwill - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill impairment charge	$ 740,600,000	$ 0	$ 740,562,000	$ 0	$ 0

Core Deposits and Other Intan_3

Core Deposits and Other Intangibles - Intangible Assets Amortization Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 11,049	$ 16,341
Accumulated amortization	(4,346)	(10,167)
Total	6,703	6,174
Core Deposit Intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	7,339	7,339
Accumulated amortization	(3,933)	(3,518)
Total	3,406	3,821
Brand Intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	0	8,464
Accumulated amortization	0	(6,392)
Total	0	2,072
Customer Relationships Intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	3,172	0
Accumulated amortization	(122)	0
Total	3,050	0
Other Intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	538	538
Accumulated amortization	(291)	(257)
Total	$ 247	$ 281

Core Deposits and Other Intan_4

Core Deposits and Other Intangibles - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of core deposits and other intangibles	$ 400,000	$ 400,000	$ 900,000	$ 800,000
Intangible asset impairment	$ 1,800,000	$ 0	$ 1,800,000	$ 0

Core Deposits and Other Intan_5

Core Deposits and Other Intangibles - Schedule of Future Amortization Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Remaining in 2020	$ 538
2021	1,014
2022	929
2023	831
2024	742
2025 and thereafter	2,649
Total	$ 6,703	$ 6,174

Leases (Details)

Leases (Details) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2020USD ($)numberOfOperatingLeases	Mar. 31, 2020USD ($)numberOfOperatingLeases
Lessee, Lease, Description [Line Items]
Lease expense | $	$ 1.9	$ 3.6
Number of operating leases, not yet commenced | numberOfOperatingLeases	0	0
Minimum
Lessee, Lease, Description [Line Items]
Lease term	1 year	1 year
Maximum
Lessee, Lease, Description [Line Items]
Lease term	15 years	15 years

Leases - Summary of ROU Assets

Leases - Summary of ROU Assets and Liabilities (Details) $ in Thousands	Mar. 31, 2020USD ($)
Leases [Abstract]
ROU asset	$ 23,143
Total lease liability	$ 24,036
Weighted average remaining lease term (in years)	6 years 8 months 12 days
Weighted average discount rate (as a percentage)	1.98%

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Mar. 31, 2020
Leases [Abstract]
Operating cash flows paid for operating leases	$ 1,416	$ 2,826
Operating leases	$ 5,007	$ 5,631

Leases - Remaining Minimum Leas

Leases - Remaining Minimum Lease Payments (Details) $ in Thousands	Mar. 31, 2020USD ($)
Leases [Abstract]
Remaining in 2020	$ 2,832
2021	4,741
2022	4,049
2023	3,580
2024	3,072
2025 and thereafter	7,500
Total undiscounted lease payments	25,774
Less: Amounts representing interest	(1,738)
Lease liability	$ 24,036

Securities Sold Under Agreeme_3

Securities Sold Under Agreements to Repurchase - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2020	Sep. 30, 2019
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities sold under agreements to repurchase	$ 81.4	$ 94.7
Securities sold under agreements to repurchase, fair value of collateral	$ 83	$ 94.4
Securities sold under agreements to repurchase, collateral, percentage of borrowed funds (as a percent)	102.00%

Securities Sold Under Agreeme_4

Securities Sold Under Agreements to Repurchase - Maturity Schedule of Agreements (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	$ 64,809	$ 68,992
Mortgage-backed securities
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	64,809	68,992
Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	64,809	68,992
Overnight and Continuous | Mortgage-backed securities
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	64,809	68,992
Up to 30 Days
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	0	0
Up to 30 Days | Mortgage-backed securities
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	0	0
30-90 Days
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	0	0
30-90 Days | Mortgage-backed securities
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	0	0
Greater than 90 Days
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	0	0
Greater than 90 Days | Mortgage-backed securities
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	$ 0	$ 0

FHLB Advances and Other Borro_3

FHLB Advances and Other Borrowings - Schedule of Advances, Related Party Notes (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Total	$ 800,000	$ 340,000
Notes payable to banks
Debt Instrument [Line Items]
Federal Home Loan Bank (FHLB) notes payable and fed funds advance	$ 325,000	325,000
Notes payable to banks | Minimum
Debt Instrument [Line Items]
Stated interest rate (as a percent)	2.36%
Notes payable to banks | Maximum
Debt Instrument [Line Items]
Stated interest rate (as a percent)	3.66%
Notes payable to banks
Debt Instrument [Line Items]
Federal Home Loan Bank (FHLB) notes payable and fed funds advance	$ 400,000	0
Notes payable to banks | Minimum
Debt Instrument [Line Items]
Stated interest rate (as a percent)	0.37%
Notes payable to banks | Maximum
Debt Instrument [Line Items]
Stated interest rate (as a percent)	0.74%
Federal Home Loan Bank fed funds advance
Debt Instrument [Line Items]
Federal Home Loan Bank (FHLB) notes payable and fed funds advance	$ 75,000	$ 15,000
Stated interest rate (as a percent)	0.35%

FHLB Advances and Other Borro_4

FHLB Advances and Other Borrowings - Narrative (Details) - USD ($)	Mar. 31, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Current borrowing capacity	$ 1,460,000,000	$ 1,800,000,000
Loans pledged to the Federal Home Loan Bank	4,110,000,000	4,200,000,000
Revolving Credit Facility | FRB Discount Window Loan
Debt Instrument [Line Items]
Borrowing capacity	1,230,000,000	1,440,000,000
Loans pledged to the Federal Reserve Board Discount Window	1,480,000,000	1,720,000,000
Letter of Credit | Federal Home Loan Bank
Debt Instrument [Line Items]
Borrowing capacity	0	170,000,000
Additional Letters of Credit | Federal Home Loan Bank
Debt Instrument [Line Items]
Borrowing capacity	$ 14,500,000	$ 14,900,000

FHLB Advances and Other Borro_5

FHLB Advances and Other Borrowings - Schedule of Due or Callable Notes (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Total	$ 108,740	$ 108,636
FHLB Advances and Related Party Notes Payable
Debt Instrument [Line Items]
Remaining in 2020	475,000
2021	120,000
2022	60,000
2023	85,000
2024	60,000
2025 and thereafter	0
Total	$ 800,000

Subordinated Debentures and S_3

Subordinated Debentures and Subordinated Notes Payable - Junior Subordinated Deferrable Interest Debentures (Details) $ / shares in Units, $ in Thousands	6 Months Ended
	Mar. 31, 2020USD ($)trust$ / sharesshares	Sep. 30, 2019USD ($)
Debt Instrument [Line Items]
Total subordinated debentures and subordinated notes payable	$ 108,740	$ 108,636
Junior Subordinated Debt
Debt Instrument [Line Items]
Total subordinated debentures and subordinated notes payable	73,765	73,697
Common shares held in other assets	$ 2,520	$ 2,520
Trust Preferred Securities Subject to Mandatory Redemption
Debt Instrument [Line Items]
Number of trusts | trust	7
Number of shares caused to be issued (in shares) | shares	73,400
Par value per shares issued (in dollars per share) | $ / shares	$ 1,000
Trust Preferred Securities Subject to Mandatory Redemption | London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.48%
Trust Preferred Securities Subject to Mandatory Redemption | London Interbank Offered Rate (LIBOR) | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	3.35%

Subordinated Debentures and S_4

Subordinated Debentures and Subordinated Notes Payable - Subordinated Notes Payable (Details) - Subordinated Debt - USD ($)	12 Months Ended
	Dec. 31, 2015	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2016
Debt Instrument [Line Items]
Face amount of debt issued				$ 35,000,000
Stated interest rate (as a percent)				4.875%
Redemption price, percentage of principal (as a percent)	100.00%
Unamortized debt issuance costs		$ 25,000	$ 61,000
London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	3.15%

Subordinated Debentures and S_5

Subordinated Debentures and Subordinated Notes Payable - Summary of Subordinated Debentures and Notes Payable (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2015	Sep. 30, 2019	Sep. 30, 2016
Debt Instrument [Line Items]
Total	$ 108,740		$ 108,636
Junior Subordinated Debt
Debt Instrument [Line Items]
Total subordinated debentures payable, amount outstanding	75,920		75,920
Total junior subordinated debentures payable, common shares held in other assets	2,520		2,520
Less: fair value adjustment	(2,155)		(2,223)
Total	73,765		73,697
Junior Subordinated Debt | GW Statutory Trust IV, variable rate of 2.85%, plus 3 month LIBOR
Debt Instrument [Line Items]
Total subordinated debentures payable, amount outstanding	23,093		23,093
Total junior subordinated debentures payable, common shares held in other assets	$ 693		693
Junior Subordinated Debt | GW Statutory Trust IV, variable rate of 2.85%, plus 3 month LIBOR | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	2.85%
Junior Subordinated Debt | GW Statutory Trust VI, variable rate of 1.48%, plus 3 month LIBOR
Debt Instrument [Line Items]
Total subordinated debentures payable, amount outstanding	$ 30,928		30,928
Total junior subordinated debentures payable, common shares held in other assets	$ 928		928
Junior Subordinated Debt | GW Statutory Trust VI, variable rate of 1.48%, plus 3 month LIBOR | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.48%
Junior Subordinated Debt | SSB Trust II, variable rate of 1.85%, plus 3 month LIBOR
Debt Instrument [Line Items]
Total subordinated debentures payable, amount outstanding	$ 2,062		2,062
Total junior subordinated debentures payable, common shares held in other assets	$ 62		62
Junior Subordinated Debt | SSB Trust II, variable rate of 1.85%, plus 3 month LIBOR | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.85%
Junior Subordinated Debt | HF Capital Trust III, variable rate of 3.35%, plus 3 month LIBOR
Debt Instrument [Line Items]
Total subordinated debentures payable, amount outstanding	$ 5,155		5,155
Total junior subordinated debentures payable, common shares held in other assets	$ 155		155
Junior Subordinated Debt | HF Capital Trust III, variable rate of 3.35%, plus 3 month LIBOR | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	3.35%
Junior Subordinated Debt | HF Capital Trust IV, variable rate of 3.10%, plus 3 month LIBOR
Debt Instrument [Line Items]
Total subordinated debentures payable, amount outstanding	$ 7,217		7,217
Total junior subordinated debentures payable, common shares held in other assets	$ 217		217
Junior Subordinated Debt | HF Capital Trust IV, variable rate of 3.10%, plus 3 month LIBOR | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	3.10%
Junior Subordinated Debt | HF Capital Trust V, variable rate of 1.83%, plus 3 month LIBOR
Debt Instrument [Line Items]
Total subordinated debentures payable, amount outstanding	$ 5,310		5,310
Total junior subordinated debentures payable, common shares held in other assets	$ 310		310
Junior Subordinated Debt | HF Capital Trust V, variable rate of 1.83%, plus 3 month LIBOR | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.83%
Junior Subordinated Debt | HF Capital Trust VI, variable rate of 1.65%, plus 3 month LIBOR
Debt Instrument [Line Items]
Total subordinated debentures payable, amount outstanding	$ 2,155		2,155
Total junior subordinated debentures payable, common shares held in other assets	$ 155		155
Junior Subordinated Debt | HF Capital Trust VI, variable rate of 1.65%, plus 3 month LIBOR | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.65%
Subordinated Debt
Debt Instrument [Line Items]
Total	$ 34,975		34,939
Less: unamortized debt issuance costs	(25)		(61)
Stated interest rate (as a percent)				4.875%
Subordinated Debt | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		3.15%
Subordinated Debt | Fixed to floating rate, 4.875% per annum
Debt Instrument [Line Items]
Total subordinated debentures payable, amount outstanding	$ 35,000		$ 35,000
Stated interest rate (as a percent)	4.875%

Profit Sharing Plan (Details)

Profit Sharing Plan (Details) - Multiple employer 401(k) profit sharing plan $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)	Mar. 31, 2020USD ($)year	Mar. 31, 2019USD ($)
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, requisite service period			1 year
Defined contribution plan, minimum age requirement (years of age) | year			21
Contributions by the Company | $	$ 1.6	$ 1.1	$ 3.3	$ 2.9

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 1.3	$ 1.4	$ 2.9	$ 3.1
Tax benefit from compensation expense	0.3	$ 0.4	0.7	$ 0.8
Share-based compensation, compensation cost not yet recognized	$ 7.7		$ 7.7
Share-based compensation, compensation cost not yet recognized, recognition period			2 years 8 months 12 days
Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of vested stock awards			$ 1.4		$ 1.9

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Restricted Share and Performance-Based Stock Award Activity (Details) - $ / shares	3 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2020	Sep. 30, 2019
Restricted shares
Common Shares
Shares, beginning of fiscal year (in shares)		190,805	163,287
Granted (in shares)	134,185		106,753
Vested (in shares)	(83,909)		(76,210)
Forfeited (in shares)	(3,109)		(3,025)
Canceled (in shares)	0		0
Shares, end of period (in shares)	237,972	237,972	190,805
Vested, but not issuable at end of period (in shares)	62,992	62,992	50,770
Weighted-Average Grant Date Fair Value
Shares, beginning of fiscal year (in dollars per share)		$ 37.20	$ 37.86
Granted (in dollars per share)	$ 32.34		37.27
Vested (in dollars per share)	38.61		38.64
Forfeited (in dollars per share)	36.61		38.67
Canceled (in dollars per share)	0		0
Shares, end of period (in dollars per share)	33.97	33.97	37.20
Vested, but not issuable at end of period (in dollars per share)	$ 33.98	$ 33.98	$ 33.88
Performance shares
Common Shares
Shares, beginning of fiscal year (in shares)		173,332	175,196
Granted (in shares)		(48,753)	60,583
Vested (in shares)		(54,861)	(59,937)
Forfeited (in shares)		(3,732)	(2,510)
Canceled (in shares)		0	0
Shares, end of period (in shares)	65,986	65,986	173,332
Vested, but not issuable at end of period (in shares)	5,612	5,612	5,612
Weighted-Average Grant Date Fair Value
Shares, beginning of fiscal year (in dollars per share)		$ 38.50	$ 36.29
Granted (in dollars per share)		(49.22)	32.77
Vested (in dollars per share)		39.43	30.79
Forfeited (in dollars per share)		38.14	39.25
Canceled (in dollars per share)		0	0
Shares, end of period (in dollars per share)	$ 34.61	34.61	38.50
Vested, but not issuable at end of period (in dollars per share)	$ 18	$ 18	$ 18

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value Measurements of Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	$ 1,990,027	$ 1,783,208
Derivatives-assets	98,723	58,534
Derivatives-liabilities	640	13
Fair value loans	792,117	812,991
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	70,583	94,745
Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,857,392	1,620,903
States and political subdivision securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	61,001	66,523
Fair value, measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,990,027	1,783,208
Derivatives-assets	98,723	58,534
Derivatives-liabilities	640	13
Fair value loans	792,117	812,991
Loan servicing rights	1,863	2,255
Fair value, measurements, recurring | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	70,583	94,745
Fair value, measurements, recurring | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,857,392	1,620,903
Fair value, measurements, recurring | States and political subdivision securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	61,001	66,523
Fair value, measurements, recurring | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,051	1,037
Fair value, measurements, recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	70,583	94,745
Derivatives-assets	0	0
Derivatives-liabilities	0	0
Fair value loans	0	0
Loan servicing rights	0	0
Fair value, measurements, recurring | Level 1 | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	70,583	94,745
Fair value, measurements, recurring | Level 1 | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Fair value, measurements, recurring | Level 1 | States and political subdivision securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Fair value, measurements, recurring | Level 1 | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Fair value, measurements, recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,915,458	1,684,343
Derivatives-assets	98,723	58,534
Derivatives-liabilities	640	13
Fair value loans	792,117	812,991
Loan servicing rights	0	0
Fair value, measurements, recurring | Level 2 | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Fair value, measurements, recurring | Level 2 | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,857,392	1,620,903
Fair value, measurements, recurring | Level 2 | States and political subdivision securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	57,015	62,403
Fair value, measurements, recurring | Level 2 | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,051	1,037
Fair value, measurements, recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	3,986	4,120
Derivatives-assets	0	0
Derivatives-liabilities	0	0
Fair value loans	0	0
Loan servicing rights	1,863	2,255
Fair value, measurements, recurring | Level 3 | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Fair value, measurements, recurring | Level 3 | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Fair value, measurements, recurring | Level 3 | States and political subdivision securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	3,986	4,120
Fair value, measurements, recurring | Level 3 | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	$ 0	$ 0

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Changes in Level 3 Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 3,986	$ 961	$ 4,120	$ 970
Additions	0	350	0	350
Principal paydown	0	0	(134)	(9)
Balance, end of period	3,986	1,311	3,986	1,311
Loan servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	2,054	2,862	2,255	3,087
Realized and unrealized (loss)	(191)	(188)	(392)	(413)
Balance, end of period	$ 1,863	$ 2,674	$ 1,863	$ 2,674

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Mortgage Loans Held-For-Sale, Fair Value Measurement (Details) - Fair value, measurements, nonrecurring - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other repossessed property	$ 21,486	$ 34,721
Impaired loans	559,155	413,644
Mortgage loans held for sale, at lower of cost or fair value	4,342	7,351
Property held for sale	706	2,757
Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other repossessed property	0	0
Impaired loans	0	0
Mortgage loans held for sale, at lower of cost or fair value	0	0
Property held for sale	0	0
Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other repossessed property	0	0
Impaired loans	0	0
Mortgage loans held for sale, at lower of cost or fair value	4,342	7,351
Property held for sale	0	0
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other repossessed property	21,486	34,721
Impaired loans	559,155	413,644
Mortgage loans held for sale, at lower of cost or fair value	0	0
Property held for sale	$ 706	$ 2,757

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Valuation Techniques and Significant Unobservable Inputs Used to Measure Level 3 Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Property held for sale	$ 706	$ 2,757
Fair value, measurements, nonrecurring
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other repossessed property	21,486	34,721
Impaired loans	559,155	413,644
Fair value, measurements, nonrecurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other repossessed property	21,486	34,721
Impaired loans	559,155	$ 413,644
Property held for sale	$ 706

Fair Value Measurements - Sch_3

Fair Value Measurements - Schedule of Fair Values for Balance Sheet Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Liabilities
Unamortized discount on acquired loans	$ 13,700	$ 13,900
Level 1 | Carrying Amount
Assets
Cash and cash equivalents	347,486	243,474
Level 1 | Fair Value
Assets
Cash and cash equivalents	347,486	243,474
Level 3 | Carrying Amount
Assets
Loans, net, excluding fair valued loans, loans held for sale and impaired loans	8,337,681	8,472,777
Level 3 | Fair Value
Assets
Loans, net, excluding fair valued loans, loans held for sale and impaired loans	8,498,042	8,533,612
Level 2 | Carrying Amount
Liabilities
Time deposits	1,528,234	2,095,676
FHLB advances and other borrowings	800,000	340,000
Securities sold under repurchase agreements	64,809	68,992
Subordinated debentures and subordinated notes payable	108,740	108,636
Level 2 | Fair Value
Liabilities
Time deposits	1,532,200	2,101,239
FHLB advances and other borrowings	818,669	351,517
Securities sold under repurchase agreements	64,809	68,992
Subordinated debentures and subordinated notes payable	$ 97,268	$ 101,164

Earnings per Share - Schedule o

Earnings per Share - Schedule of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net (loss) income	$ (740,618)	$ 44,511	$ (697,344)	$ 90,297
Weighted average common shares outstanding (in shares)	55,906,002	56,994,817	56,141,816	57,484,838
Dilutive effect of stock based compensation (in shares)	0	79,857	0	72,146
Weighted average common shares outstanding for diluted earnings per share calculation (in shares)	55,906,002	57,074,674	56,141,816	57,556,984
Basic earnings per share (in dollars per share)	$ (13.25)	$ 0.78	$ (12.42)	$ 1.57
Diluted earnings per share (in dollars per share)	$ (13.25)	$ 0.78	$ (12.42)	$ 1.57

Earnings per Share - Narrative

Earnings per Share - Narrative (Details) - shares	6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Performance shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of earnings per share (in shares)	5,037	0
Stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of earnings per share (in shares)	63,076	67,971

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 12,974	$ 13,444	$ 28,015	$ 27,955
Noninterest income within the scope of other GAAP Topics	(13,057)	4,779	(12,365)	6,988
Total noninterest (loss) income	(83)	18,223	15,650	34,943
Service charges and other fees
Disaggregation of Revenue [Line Items]
Revenue	9,188	10,209	20,597	21,897
Wealth management fees
Disaggregation of Revenue [Line Items]
Revenue	3,122	2,117	6,086	4,358
Other
Disaggregation of Revenue [Line Items]
Revenue	$ 664	$ 1,118	$ 1,332	$ 1,700

Acquisition Activity (Details)

Acquisition Activity (Details) - Independent Bank - USD ($) $ in Thousands	Oct. 01, 2019	Mar. 31, 2020
Business Acquisition [Line Items]
Loans under management, amount	$ 306,000
Consideration transferred	$ 4,711
Customer Relationships Intangible
Business Acquisition [Line Items]
Estimated useful life (in years)		13 years

Acquisition Activity - Purchase

Acquisition Activity - Purchase Price Summary (Details) - USD ($) $ in Thousands	Oct. 01, 2019	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2018
Business Acquisition [Line Items]
Goodwill		$ 0	$ 739,023	$ 739,023
Independent Bank
Business Acquisition [Line Items]
Total consideration paid	$ 4,711
Goodwill	1,539
Independent Bank | Customer Relationships Intangible
Business Acquisition [Line Items]
Customer relationship intangible	$ 3,172