Great Western Bancorp (GWB) 10-K 27 Nov 19 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Sep. 30, 2019	Nov. 22, 2019	Mar. 31, 2019
Cover page.
Entity Registrant Name	Great Western Bancorp, Inc.
Entity Central Index Key	0001613665
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Document Transition Report	false
Document Annual Report	true
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
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
Entity Tax Identification Number	47-1308512
Entity File Number	001-36688
Entity Small Business	false
Title of 12(b) Security	Common Stock, $0.01 par value per share
Trading Symbol	GWB
Security Exchange Name	NYSE
Entity Interactive Data Current	Yes
Entity Emerging Growth Company	false
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Public Float			$ 1,798,685,162
Entity Common Stock, Shares Outstanding (in shares)		56,284,089

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Assets [Abstract]
Cash and due from banks	$ 201,487	$ 168,119
Interest-bearing bank deposits	41,987	130,577
Cash and cash equivalents	243,474	298,696
Securities available for sale	1,783,208	1,385,650
Loans, net of unearned discounts and deferred fees, including $31,891 and $42,627 of loans covered by a FDIC loss share agreement at September 30, 2019 and September 30, 2018, respectively, and $812,991 and $865,386 of loans at fair value under the fair value option at September 30, 2019 and September 30, 2018, respectively, and $7,351 and $5,456 of loans held for sale at September 30, 2019 and September 30, 2018, respectively	9,706,763	9,415,924
Allowance for loan and lease losses	(70,774)	(64,540)
Net loans	9,635,989	9,351,384
Premises and equipment, including $2,757 and $1,104 of property held for sale at September 30, 2019 and September 30, 2018, respectively	120,645	113,839
Accrued interest receivable	58,699	58,948
Other repossessed property, including $0 and $131 of property covered by a FDIC loss share agreement at September 30, 2019 and September 30, 2018, respectively	36,764	23,074
Goodwill	739,023	739,023
Cash surrender value of life insurance policies	30,796	30,461
Net deferred tax assets	7,286	30,132
Other assets	132,417	85,601
Total assets	12,788,301	12,116,808
Deposits
Noninterest-bearing	1,956,025	1,842,704
Interest-bearing	8,344,314	7,890,795
Total deposits	10,300,339	9,733,499
Securities sold under agreements to repurchase	68,992	90,907
FHLB advances and other borrowings	340,000	275,000
Subordinated debentures and subordinated notes payable	108,636	108,468
Accrued expenses and other liabilities	70,085	68,383
Total liabilities	10,888,052	10,276,257
Stockholders’ equity
Common stock, $0.01 par value, authorized 500,000,000 shares; 56,283,659 shares issued and outstanding at September 30, 2019 and 58,917,147 shares issued and outstanding at September 30, 2018	563	589
Additional paid-in capital	1,228,714	1,318,457
Retained earnings	657,475	553,014
Accumulated other comprehensive income (loss)	13,497	(31,509)
Total stockholders' equity	1,900,249	1,840,551
Total liabilities and stockholders' equity	$ 12,788,301	$ 12,116,808

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Assets [Abstract]
Loans covered by FDIC loss share agreement	$ 31,891	$ 42,627
Loans and written loan commitments at fair value under the fair value option	812,991	865,386
Loan held for sale	7,351	5,456
Property held for sale	2,757	1,104
Property covered by FDIC loss share arrangements	$ 0	$ 131
Liabilities and 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)	56,283,659	58,917,147
Common stock, shares outstanding (in shares)	56,283,659	58,917,147

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Interest income
Loans	$ 498,935	$ 451,290	$ 407,282
Investment securities	41,510	29,171	26,311
Federal funds sold and other	2,472	1,376	922
Total interest income	542,917	481,837	434,515
Interest expense
Deposits	106,718	60,112	35,035
FHLB advances and other borrowings	9,951	8,848	5,821
Subordinated debentures and subordinated notes payable	5,540	5,040	4,464
Total interest expense	122,209	74,000	45,320
Net interest income	420,708	407,837	389,195
Provision for loan and lease losses	40,947	17,986	21,539
Net interest income after provision for loan and lease losses	379,761	389,851	367,656
Noninterest income
Service charges and other fees	43,893	51,077	55,725
Wealth management fees	8,914	9,219	9,118
Mortgage banking income, net	4,848	5,842	7,928
Net (loss) gain on sale of securities	(178)	6	75
Net increase (decrease) in fair value of loans at fair value	61,412	(45,407)	(65,231)
Net realized and unrealized (loss) gain on derivatives	(63,444)	44,596	49,900
Other	5,287	8,276	5,699
Total noninterest income	60,732	73,609	63,214
Noninterest expense
Salaries and employee benefits	136,305	135,352	128,135
Data processing and communication	24,077	29,805	28,288
Occupancy and equipment	20,784	20,330	19,817
Professional fees	14,579	17,891	15,038
Advertising	4,493	4,507	3,983
Net loss on repossessed property and other related expenses	4,367	4,369	1,749
Acquisition expenses	0	0	710
Other	20,293	19,171	18,923
Total noninterest expense	224,898	231,425	216,643
Income before income taxes	215,595	232,035	214,227
Provision for income taxes	48,230	74,119	69,441
Net income	$ 167,365	$ 157,916	$ 144,786
Basic earnings per common share
Weighted average shares outstanding, basic (in shares)	57,154,865	58,938,169	58,770,708
Basic earnings per share (in dollars per share)	$ 2.93	$ 2.68	$ 2.46
Diluted earnings per common share
Weighted average shares outstanding, diluted (in shares)	57,257,061	59,131,650	59,029,382
Diluted earnings per share (in dollars per share)	$ 2.92	$ 2.67	$ 2.45
Dividends per share
Dividends paid	$ 62,904	$ 53,002	$ 43,474
Dividends per share (in dollars per share)	$ 1.10	$ 0.90	$ 0.74

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income		$ 167,365	$ 157,916	$ 144,786
Securities available for sale:
Net unrealized holding gain (loss) arising during the period		59,550	(32,816)	(17,848)
Reclassification adjustment for net loss (gain) realized in net income		178	(6)	(75)
Income tax (expense) benefit		(14,722)	9,244	6,811
Net change in unrealized gain (loss) on securities available for sale		45,006	(23,578)	(11,112)
Defined benefit pension plan obligation ¹:
Net unrealized holding gain (loss) arising during the period	[1]	0	(329)	329
Income tax (expense) benefit	[1]	0	125	(125)
Net change in unrealized gain (loss) in defined benefit pension plan obligation	[1]	0	(204)	204
Other comprehensive income (loss), net of tax	[1]	45,006	(23,782)	(10,908)
Comprehensive income		$ 212,371	$ 134,134	$ 133,878
[1]	The Company's Board of Directors voted to terminate the defined benefit pension plan ("Pension Plan") effective February 1, 2018. Transfer of all Pension Plan assets, liabilities and administrative responsibilities were completed as of September 30, 2018.

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		Total		Comprehensive Income	Common Stock Par Value	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Sep. 30, 2016		$ 1,663,391			$ 587	$ 1,312,347	$ 344,923	$ 5,534
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		144,786		$ 144,786			144,786
Other comprehensive (loss), net of tax		(10,908)	[1]	(10,908)				(10,908)
Comprehensive income		133,878		133,878
Stock-based compensation, net of tax		6,547			2	6,545
Repurchase of common stock		(5,605)			(1)	(5,604)
Cash dividends:
Common stock, $0.74, $0.90, and $1.10 per share in 2017, 2018 and 2019, respectively		(43,474)					(43,474)
Ending balance at Sep. 30, 2017		1,755,000			588	1,314,039	445,747	(5,374)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		157,916		157,916			157,916
Other comprehensive (loss), net of tax		(23,782)	[1]	(23,782)				(23,782)
Comprehensive income		134,134		134,134
Stock-based compensation, net of tax		4,419			1	4,418
Reclassification due to adoption of ASU 2018-02	[2]	0					2,353	(2,353)
Cash dividends:
Common stock, $0.74, $0.90, and $1.10 per share in 2017, 2018 and 2019, respectively		(53,002)					(53,002)
Ending balance at Sep. 30, 2018		1,840,551			589	1,318,457	553,014	(31,509)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		167,365		167,365			167,365
Other comprehensive (loss), net of tax		45,006	[1]	45,006				45,006
Comprehensive income		212,371		$ 212,371
Stock-based compensation, net of tax		4,582			1	4,581
Repurchase of common stock		(94,351)			(27)	(94,324)
Cash dividends:
Common stock, $0.74, $0.90, and $1.10 per share in 2017, 2018 and 2019, respectively		(62,904)					(62,904)
Ending balance at Sep. 30, 2019		$ 1,900,249			$ 563	$ 1,228,714	$ 657,475	$ 13,497
[1]	The Company's Board of Directors voted to terminate the defined benefit pension plan ("Pension Plan") effective February 1, 2018. Transfer of all Pension Plan assets, liabilities and administrative responsibilities were completed as of September 30, 2018.
[2]	Reclassification due to adoption of ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income .

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Statement of Stockholders' Equity [Abstract]
Cash dividends paid on common stock (in dollars per share)	$ 1.10	$ 0.90	$ 0.74

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Operating activities
Net income	$ 167,365	$ 157,916	$ 144,786
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	13,655	13,093	13,599
Amortization of FDIC indemnification asset	1,386	2,778	4,748
Net loss on sale of securities and other assets	2,825	5,731	2,545
Gain on redemption of subordinated debentures	0	0	(111)
Net gain on sale of loans	(5,680)	(6,829)	(9,635)
Provision for loan and lease losses	40,947	17,986	21,539
(Reversal of) provision for loan servicing rights loss	(4)	(73)	68
Stock-based compensation	4,582	4,419	6,810
Originations of residential real estate loans held for sale	(289,973)	(264,514)	(275,015)
Proceeds from sales of residential real estate loans held for sale	293,758	273,343	290,111
Net deferred income taxes	8,124	21,302	2,631
Changes in:
Accrued interest receivable	249	(5,772)	(3,645)
Other assets	(48,524)	(34,209)	(2,405)
Accrued interest payable and other liabilities	2,949	(2,742)	(64,517)
Net cash provided by operating activities	191,659	182,429	131,509
Investing activities
Purchase of securities available for sale	(774,707)	(334,900)	(313,701)
Proceeds from sales of securities available for sale	175,007	24,971	5,074
Proceeds from maturities of securities available for sale	257,201	254,985	233,357
Net increase in loans	(348,479)	(490,804)	(318,876)
Payment of covered losses from FDIC indemnification claims	(14)	(770)	(706)
Purchase of premises and equipment	(15,643)	(13,878)	(6,409)
Proceeds from sale of premises and equipment	606	4,599	5,260
Proceeds from sale of repossessed property	9,981	7,468	7,334
Purchase of FHLB stock	(89,948)	(64,172)	(38,345)
Proceeds from redemption of FHLB stock	87,528	79,190	47,819
Net cash used in investing activities	(698,468)	(533,311)	(379,193)
Financing activities
Net increase in deposits	567,004	756,145	373,408
Net (decrease) increase in securities sold under agreements to repurchase and other short-term borrowings	(21,915)	(41,729)	347,148
Proceeds from FHLB advances and other long-term borrowings	810,000	150,000	0
Repayments on FHLB advances and other long-term borrowings	(745,000)	(518,200)	(584,000)
Redemption of subordinated debentures	0	0	(3,625)
Common stock repurchased	(94,351)	0	(5,605)
Taxes paid related to net share settlement of equity awards	(1,247)	(4,032)	(383)
Dividends paid	(62,904)	(53,002)	(43,474)
Net cash provided by financing activities	451,587	289,182	83,469
Net decrease in cash and cash equivalents	(55,222)	(61,700)	(164,215)
Cash and cash equivalents, beginning of period	298,696	360,396	524,611
Cash and cash equivalents, end of period	243,474	298,696	360,396
Supplemental disclosure of cash flow information
Cash payments for interest	114,891	69,633	44,989
Cash payments for income taxes	46,884	50,020	71,964
Supplemental disclosure of noncash investing and financing activities
Loans transferred to repossessed properties	$ (25,668)	$ (25,926)	$ (7,786)

Nature of Operations and Summar

Nature of Operations and Summary of Significant Accounting Policies	12 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Nature of Operations and Summary of Significant Accounting 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. Segment Reporting The "Segment Reporting" topic of the FASB ASC requires that public companies report certain information about operating segments. It also requires that public companies report certain information about their products and services, the geographic areas in which they operate, and their major customers. The Company is a holding company for a regional bank, which offers a wide array of products and services to its customers. Pursuant to its banking strategy, emphasis is placed on building relationships with its customers, as opposed to building specific lines of business. As a result, the Company is not organized and does not allocate resources around discernible lines of business or geographies and prefers to work as an integrated unit to customize solutions for its customers, with business line and geographic emphasis and product offerings changing over time as needs and demands change. Therefore, the Company only reports one segment, which is consistent with the Company’s preparation of financial information that is evaluated regularly by management in deciding how to allocate resources and assess performance. Basis of Presentation and Principles of Consolidation The accounting and reporting policies of the Company conform with U.S. GAAP, SEC rules and interpretive releases and prevailing practices within the banking industry. All significant income and expenses are recorded on the accrual basis. The accompanying consolidated financial statements include the accounts and results of the Company and its subsidiaries after elimination of all significant intercompany accounts and transactions. The Company determines whether it has a controlling financial interest in an entity by first evaluating whether the entity is a voting interest entity or a variable interest entity under U.S. GAAP. Voting interest entities are entities in which the total equity investment at risk is sufficient to enable the entity to finance itself independently and provides the equity holders with the obligation to absorb losses, the right to receive residual returns and the right to make decisions about the entity’s activities. The Company consolidates voting interest entities in which it has all, or at least a majority of, the voting interest. As defined in applicable accounting standards, VIEs are entities that lack one or more of the characteristics of a voting interest entity. A controlling financial interest in a VIE is present when an enterprise has both the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and an obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. The enterprise with a controlling financial interest, known as the primary beneficiary, consolidates the VIE. The Company’s wholly-owned subsidiaries Great Western Statutory Trust IV, GWB Capital Trust VI, Sunstate Bancshares Trust II, HF Financial Capital Trust III, HF Financial Capital Trust IV, HF Financial Capital Trust V and HF Financial Capital Trust VI are VIEs for which the Company is not the primary beneficiary. Accordingly, the accounts of these trusts are not included on the Company’s consolidated financial statements. Certain previously reported amounts have been reclassified to conform to the current presentation. Use of Estimates U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported on the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. Subsequent Events On October 24, 2019, the Board of Directors of the Company declared a dividend of $0.30 per common share payable on November 29, 2019 to stockholders of record as of close of business on November 15, 2019. On October 1, 2019, the Company purchased and assumed the management of approximately $306.0 million of trust assets managed in Colorado from Independent Bank, a wholly owned subsidiary of Independent Bank Group, Inc. for the consideration of $4.7 million. The Company is the in the process of determining preliminary fair values as of the acquisition date in accordance with ASC Topic 805, but does not believe the transaction will have a material impact on the consolidated financial statements. The Company evaluated subsequent events through the date its consolidated financial statements were issued. Other than those described above, there were no other material events or transactions that would require recognition on the consolidated financial statements or disclosure in the notes to the consolidated financial statements. Business Combinations The Company accounts for business combinations under the acquisition method of accounting in accordance with ASC Topic 805, Business Combinations ("ASC 805"). The Company recognizes the fair value of the assets acquired and liabilities assumed, immediately expenses transaction costs and accounts for restructuring plans separately from the business combination. There is no separate recognition of the acquired allowance for loan and lease losses on the acquirer’s balance sheet as credit related factors are incorporated directly into the fair value of the loans recorded at the acquisition date. The excess of the cost of the acquisition over the fair value of the net tangible and intangible assets acquired is recorded as goodwill. Alternatively, a bargain purchase gain is recorded equal to the amount by which the fair value of assets purchased exceeds the fair value of liabilities assumed and consideration paid. Results of operations of the acquired business are included on the consolidated statements of income from the effective date of acquisition. Fair values are subject to refinement for up to a year after the closing date of an acquisition as information relative to closing date fair values becomes available. Adjustments recorded to the acquired assets and liabilities are applied prospectively in accordance with ASU 2015-16. Cash and Cash Equivalents For purposes of the consolidated statements of cash flows, management has defined cash and cash equivalents to include cash on hand, amounts due from banks (including cash items in process of clearing), and amounts held at other financial institutions with an initial maturity of 90 days or less. Securities The Company classifies securities upon purchase in one of three categories: trading, held to maturity, or available for sale. Debt and equity securities held for resale are classified as trading. Debt securities for which the Company has the ability and positive intent to hold until maturity are classified as held to maturity. All other securities are classified as available for sale as they may be sold prior to maturity in response to changes in the Company’s interest rate risk profile, funding needs, demand for collateralized deposits by public entities or other reasons. Held to maturity securities are stated at amortized cost, which represents actual cost adjusted for premium amortization and discount accretion. Available for sale securities are stated at fair value, with unrealized gains and losses, net of related taxes, included in stockholders’ equity as a component of accumulated other comprehensive income (loss). Trading securities are stated at fair value. Realized and unrealized gains and losses from sales and fair value adjustments of trading securities are included in other noninterest income on the consolidated statements of income. Purchases and sales of securities are recognized on a trade date basis. The cost of securities sold is based on the specific identification method. Declines in the fair value of investment securities available for sale that are deemed to be other-than-temporary are recognized in earnings as a realized loss, and a new cost basis for the securities is established. In evaluating other-than-temporary impairment, management considers the length of time and extent to which the fair value has been less than amortized cost, the financial condition and near-term prospects of the issuer, and the intent and ability of the Company to retain its investment in the issuer for a period of time sufficient to allow for any anticipated recovery in fair value in the near term. Declines in the fair value of debt securities below amortized cost are deemed to be other-than-temporary in circumstances where: (1) the Company has the intent to sell a security; (2) it is more-likely-than-not that the Company will be required to sell the security before recovery of its amortized cost basis; or (3) the Company does not expect to recover the entire amortized cost basis of the security. If the Company intends to sell a security or if it is more-likely-than-not that the Company will be required to sell the security before recovery, an other-than-temporary impairment loss is recognized in earnings equal to the difference between the security’s amortized cost basis and its fair value. If the Company does not intend to sell the security or it is not more-likely-than-not that it will be required to sell the security before recovery, the other-than-temporary impairment write-down is separated into an amount representing credit loss, which is recognized in earnings, and an amount related to all other factors, which is recognized in other comprehensive income (loss). Interest and dividends, including amortization of premiums and accretion of discounts, are recognized as interest income when earned. Realized gains and losses on sales (using the specific identification method) and declines in value judged to be other-than-temporary are included in noninterest income on the consolidated statements of income. Federal Home Loan Bank Stock Investments in the FHLB stock are restricted as to redemption and are carried at cost. Investments in FHLB stock are reviewed regularly for possible other-than-temporary impairment, and the cost basis of this investment is reduced by any declines in value determined to be other-than-temporary. FHLB stock is included in other assets on the consolidated balance sheets. Loans The Company’s accounting method for loans differs depending on whether the loans were originated or purchased and, for purchased loans, whether the loans were acquired at a discount related to evidence of credit deterioration since date of origination. Originated Loans Loans that management has the intent and ability to hold for the foreseeable future, or until maturity or pay-off, usually are reported at their outstanding principal balance, adjusted for charge-offs, the allowance for loan and lease losses, and any unamortized deferred fees or costs. Other fees not associated with originating a loan are recognized as fee income when earned. 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 Company has elected to measure certain long-term loans and written loan commitments at fair value to assist in managing interest rate risk for longer-term loans. Fair value loans are fixed-rate loans having original maturities of 5 years or greater (typically between 5 and 15 years) to our business and agri-business banking customers to assist them in facilitating their risk management strategies. The fair value option was elected upon the origination or acquisition of these loans and written loan commitments. Interest income is recognized in the same manner on loans reported at fair value as on non-fair value loans, except in regard to origination fees and costs which are recognized immediately upon closing. The changes in fair value of long-term loans and written loan commitments at fair value are reported in noninterest income. For loans held for sale, loan fees charged or received on origination, net of certain direct loan origination costs, are recognized in income when the related loan is sold. For loans held for investment, loan fees, net of certain direct loan origination costs, are deferred and the net amount is amortized as an adjustment of the related loan’s yield. The Company is generally amortizing these amounts over the contractual lives of the loans. Commitment fees are recognized as income when received. The Company makes commercial, agricultural, residential real estate, consumer and other loans to customers primarily in Arizona, Colorado, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota and South Dakota. The amount of collateral obtained, if deemed necessary, is based on management’s credit evaluation of the borrower. Collateral held varies but includes accounts receivable, marketable securities, inventory, equipment and real estate. Personal guarantees of the borrower or related parties and government guarantees are also obtained for some loans, which reduces the Company’s risk of loss. Loans originated and intended for sale in the secondary market are carried at the lower of cost or fair value. Loans held for sale include fixed rate single-family residential mortgage loans under contract to be sold in the secondary market. In most cases, loans are carried at cost and sold within 45 days. These loans are sold with the mortgage servicing rights released. Under limited circumstances, buyers may have recourse to return a purchased loan to the Company. Recourse conditions may include early payment default, breach of representation or warranties, or documentation deficiencies. Fair value of loans held for sale is determined based on prevailing market prices for loans with similar characteristics, sale contract prices, or, for certain portfolios, discounted cash flow analysis. Declines in fair value below cost (and subsequent recoveries) are recognized in net gain on sale of loans. Deferred fees and costs related to these loans are not amortized but are recognized as part of the cost basis of the loan at the time it is sold. Gains or losses on sales are recognized upon delivery and included in net gain on sale of loans. Purchased Loans Loans acquired (non-impaired and impaired) in a business acquisition are recorded at their fair value at the acquisition date. Credit discounts are included in the determination of fair value; therefore, an allowance for loan and lease losses is not recorded at the acquisition date. In determining the acquisition date fair value of purchased loans with evidence of credit deterioration ("purchased impaired loans"), and in subsequent accounting, the Company generally aggregates impaired purchased consumer and certain smaller balance impaired commercial loans into pools of loans with common risk characteristics, while accounting for larger-balance impaired commercial loans individually. Expected cash flows at the acquisition date in excess of the fair value of loans are recorded as interest income over the life of the loans using a level-yield method. Management estimates the cash flows expected to be collected at acquisition and at subsequent measurement dates using internal risk models, which incorporate the estimate of key assumptions, such as default rates, loss severity, and prepayment speeds. Subsequent to the acquisition date, decreases in cash flows over those expected at the acquisition date are recognized by recording an allowance for loan and lease losses. Subsequent increases in cash flow over those expected at the acquisition date are recognized as reductions to allowance for loan and lease losses to the extent impairment was previously recognized and thereafter as interest income prospectively. For purchased loans not deemed impaired at the acquisition date, the difference between the fair value and the unpaid principal balance of the loan at acquisition date is amortized or accreted to interest income using the effective interest method over the remaining period to contractual maturity. Credit Risk Management The Company’s strategy for credit risk management includes well-defined, centralized credit policies, uniform underwriting criteria and ongoing risk monitoring and review processes for all credit exposures. The strategy also emphasizes diversification on a geographic, industry, loan class type, and customer level; regular credit examinations; and management reviews of loans exhibiting deterioration of credit quality. The credit risk management strategy also includes a credit risk assessment process that performs assessments of compliance with commercial and consumer credit policies, risk ratings, and other critical credit information. Loan decisions are documented with respect to the borrower’s business, purpose of the loan, evaluation of the repayment sources, and the associated risks, evaluation of collateral, covenants and monitoring requirements, and risk rating rationale. The Company categorizes its loan portfolio into six classes, which is the level at which it develops and documents a systematic methodology to determine the allowance for loan and lease losses. The Company’s six loan portfolio classes are commercial real estate, agriculture, commercial non-real estate, residential real estate, consumer and other lending. The commercial real estate lending class includes loans made to small and middle market businesses, including multi-family properties. Loans in this class are generally secured by commercial real estate with cash flows generally being the primary source of repayment. Historical loss history and updated loan-to-value information on collateral-dependent loans are the primary factors in determining the allowance for loan and lease losses for the commercial real estate lending class. Key risk characteristics relevant to the commercial real estate lending class include the industry and geography of the borrower’s business, purpose of the loan, repayment sources, borrower’s debt capacity and financial performance, loan covenants, guarantees and nature of pledged collateral. The Company considers these risk characteristics in assigning risk ratings and estimating environmental factors considered in determining the allowance for loan and lease losses. The agriculture lending class includes loans made to agricultural individuals and businesses. Loans in this class are generally secured by operating assets and agriculture real estate and guaranteed by owners; cashflows are most often the primary source of repayment. Historical loss history and updated loan-to-value information on collateral-dependent loans are the primary factors in determining the allowance for loan and lease losses for the agriculture lending class. Key risk characteristics relevant to the agriculture lending class include the geography of the borrower’s operations, commodity prices and weather patterns, purpose of the loan, repayment sources, borrower’s debt capacity and financial performance, loan covenants, guarantees and nature of pledged collateral. The Company considers these risk characteristics in assigning risk ratings and estimating environmental factors considered in determining the allowance for loan and lease losses. The commercial non-real estate lending class includes loans made to small and middle market businesses, and loans made to public sector customers. Loans in this class are generally secured by business assets and guaranteed by owners; cashflows are most often a primary source of repayment. Historical loss history and updated loan-to-value information on collateral-dependent loans are the primary factors in determining the allowance for loan and lease losses for the commercial non-real estate lending class. Key risk characteristics relevant to the commercial non-real estate lending class include the industry and geography of the borrower’s business, purpose of the loan, repayment sources, borrower’s debt capacity and financial performance, loan covenants, guarantees and nature of pledged collateral. The Company considers these risk characteristics in assigning risk ratings and estimating environmental factors considered in determining the allowance for loan and lease losses. The residential real estate lending class includes loans made to consumer customers including residential mortgages, residential construction loans and home equity loans and lines. These loans are typically fixed rate loans secured by residential real estate. Home equity lines are revolving accounts giving the borrower the ability to draw and repay balances repeatedly, up to a maximum commitment, and are secured by residential real estate. Home equity lines typically have variable rate terms which are benchmarked to a prime rate. Historical loss history is the primary factor in determining the allowance for loan and lease losses for the residential real estate lending class. Key risk characteristics relevant to residential real estate lending class loans primarily relate to the borrower’s capacity and willingness to repay and include unemployment rates and other economic factors, and customer payment history. These risk characteristics, among others, are reflected in the environmental factors considered in determining the allowance for loan and lease losses. The consumer lending class includes loans made to consumer customers including loans secured by automobiles and other installment loans, and the other lending class includes credit card loans and unsecured revolving credit lines. Historical loss history is the primary factor in determining the allowance for loan and lease losses for the consumer and other lending classes. Key risk characteristics relevant to loans in the consumer and other lending classes primarily relate to the borrower’s capacity and willingness to repay and include unemployment rates and other economic factors, and customer payment and overall credit history. These risk characteristics, among others, are reflected in the environmental factors considered in determining the allowance for loan and lease losses. The other lending class includes all other loan relationships that do not fit within the categories above, primarily consumer and commercial credit cards, customer deposit account overdrafts, and lease receivables. 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 loan risk ratings are updated and monitored 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 consumer loans. Troubled Debt Restructurings Loans modified under troubled debt restructurings involve granting a concession to a borrower who is experiencing financial difficulty. These concessions could include a reduction in the interest rate on the loan, payment extensions, forgiveness of principal, forbearance, or other actions intended to maximize collection, which generally would not otherwise be considered. The Company's TDRs include performing and nonperforming TDRs, which consist of loans that continue to accrue interest at the loan's original interest rate when the Company expects to collect the remaining principal and interest on the loan, and nonaccrual TDRs, which include loans that are in a nonaccrual status and are no longer accruing interest, as the Company does not expect to collect the full amount of principal and interest owed from the borrower on these loans. At the time of modification (except for loans on nonaccrual status), a TDR is classified as nonperforming TDR until a six-month payment history of principal and interest payments, in accordance with the terms of the loan modification, is sustained, at which time the loan is moved to a performing status (performing TDR). If the Company does not expect to collect all principal and interest on the loan, the modified loan is classified as a nonaccrual TDR. All TDRs are accounted for as impaired loans and are included in the analysis of the allowance for loan and lease losses. A TDR that has been renewed for a borrower who is no longer experiencing financial difficulty and which yields a market rate of interest at the time of a renewal is no longer considered a TDR. Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments The Company maintains an allowance for loan and lease losses at a level believed to be appropriate to reserve for credit losses inherent in the loan portfolio. The allowance for loan and lease losses 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 and current economic conditions 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 and macroeconomic factors, such as changes in unemployment rates, gross domestic product, and consumer bankruptcy filings. All of these estimates are susceptible to significant change. 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. A loan is placed on nonaccrual status and accrual of interest is discontinued 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. 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 troubled debt restructurings. 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 Company maintains an ALLL for acquired impaired loans accounted for under ASC 310-30, resulting from decreases in expected cash flows arising from the periodic revaluation of these loans. Any decrease in expected cash flows in the individual loan pool is generally recognized in the current provision for loan and lease losses. Any increase in expected cash flows is generally not recognized immediately but is instead reflected as an adjustment to the related loan or pool's yield on a prospective basis once any previously recorded provision for loan and lease loss has been reversed. For acquired non-impaired loans accounted for under ASC 310-20, the Company utilizes methods to estimate the required allowance for loan and lease losses similar to originated loans; the required reserve is compared to the net carrying value of each acquired non-impaired loan (by class) to determine if a provision is required. Unfunded residential mortgage loan commitments entered into in connection with mortgage loans to be held for sale are considered derivatives and are recorded at fair value and included in other liabilities on the consolidated balance sheets with changes in fair value recorded in other interest income. All other unfunded loan commitments are generally related to providing credit facilities to customers and are not considered derivatives. For purchased loans, the fair value of the unfunded credit commitments is considered in determination of the fair value of the loans recorded at the date of acquisition. Reserves for credit exposure on all other unfunded credit commitments are recorded in other liabilities on the consolidated balance sheets. The Company maintains a reserve for unfunded commitments at a level believed to be sufficient to absorb estimated probable losses related to unfunded credit facilities. FDIC Indemnification Asset and Clawback Liability In conjunction with a FDIC assisted transaction of TierOne Bank in 2010, the Company entered into a loss share agreement with the FDIC covering certain single family residential mortgage loans with claim period ending June 2020. The agreement covers a portion of realized losses on loans, foreclosed real estate and certain other assets. The Company has recorded indemnification assets in other assets on the consolidated balance sheets representing estimated future amounts recoverable from the FDIC. Fair values of loans covered by the loss sharing agreement at the acquisition date were estimated based on projected cash flows available based on the expected probability of default, de

New Accounting Standards

New Accounting Standards	12 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
New Accounting Standards	Accounting Standards Adopted in Fiscal Year 2019 In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting , which provided guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. Under ASU 2017-09, an entity will not apply modification accounting to a share-based payment award if all of the following are the same immediately before and after the change: (i) the award's fair value, (ii) the award's vesting conditions and (iii) the award's classification as an equity or liability instrument. The Company adopted the standard effective October 1, 2018 on a prospective basis. The adoption did not have a material impact on the consolidated financial statements. In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business , which contained amendments that clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. Under the existing implementation guidance in Topic 805, there are three elements of a business: inputs, processes, and outputs. While an integrated set of assets and activities (collectively referred to as a “set”) that is a business usually has outputs, outputs are not required to be present. In addition, all the inputs and processes that a seller uses in operating a set are not required if market participants can acquire the set and continue to produce outputs. ASU 2017-01 amendments provided a screen to determine when a set is not a business. If the screen is not met, the amendments (1) require that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output and (2) remove the evaluation of whether a market participant could replace missing elements. ASU 2017-01 provided a framework to assist entities in evaluating whether both an input and a substantive process are present. The Company adopted the standard effective October 1, 2018 on a prospective basis. The adoption did not have an impact on the consolidated financial statements. In October 2016, the FASB issued ASU 2016-17, Consolidation (Topic 810): Interests held through Related Parties that are under Common Control , which altered how a decision maker needs to consider indirect interests in a variable interest entity held through an entity under common control and simplified that analysis to require consideration of only an entity’s proportionate indirect interest in a VIE held through a common control party. The Company adopted the standard effective October 1, 2018. The adoption did not have an impact on the consolidated financial statements. In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Equity Transfers of Assets Other Than Inventory , which addressed improvement in accounting for income tax consequences of intra-equity transfers of assets other than inventory. This update required that an entity recognize the income tax consequences of the intra-equity transfer of an asset other than inventory when the transfer occurs. The update eliminated the exception for an intra-equity transfer for assets other than inventory. The Company adopted the standard effective October 1, 2018 using the modified retrospective transaction approach with no cumulative effect adjustments as a result of implementation. The adoption did not have an impact on the consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) , which addressed eight specific cash flow issues with the objective of reducing the existing diversity in presentations and classification in the statement of cash flows. The eight specific cash flow issues addressed include: debt prepayment or debt extinguishment costs; settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing; contingent consideration payments made after a business combination; proceeds from the settlement of insurance claims; proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; distributions received from equity method investees; beneficial interests in securitization transactions; and separately identifiable cash flows and application of the predominance principle. The Company adopted the standard effective October 1, 2018 using the retrospective transaction approach. The adoption did not have an impact on the consolidated financial statements. In January 2016, the FASB issued ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10) - Recognition and Measurement of Financial Assets and Financial Liabilities , which required equity investments, in general, to be measured at fair value with changes in fair value recognized in earnings. It also eliminated the requirement to disclose the methods and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost, required entities to use the "exit price" notion when measuring fair value, required an entity to present separately in other comprehensive income the portion of the total change in fair value of a liability resulting from a change in the measurement category and form on the balance sheet or accompanying notes, clarified that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available for sale securities in combination with the entity's other deferred tax assets, and simplified the impairment assessment of equity investments without readily determinable fair values. In February 2018, the FASB issued ASU 2018-03, Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10) , which clarified certain aspects of the guidance issued in ASU 2016-01. The Company adopted these standards effective October 1, 2018. Disclosure requirements were adopted on a prospective basis and there were no cumulative effect adjustments as a result of implementation. The adoption did not have a material impact on the consolidated financial statements. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) , which implemented a more robust framework that clarified the principles for recognizing revenue and gave greater consistency and comparability in revenue recognition practices. In the new framework, revenue is recognized in an amount that reflects the consideration to which the entity expects to be entitled in exchange for goods or services. The new model requirements include the identification of performance obligations in the contract with customers, a determination of the transaction price and an allocation of the price to those performance obligations. Revenue is recognized when performance obligations are satisfied. In 2015, the FASB issued ASU 2015-14, which deferred the effective date of ASU 2014-09 to annual reporting periods beginning after December 15, 2017. In 2016, the FASB issued ASU 2016-08, ASU 2016-10, ASU 2016-11, ASU 2016-12 and ASU 2016-20, all of which further clarified the implementation guidance, provided practical expedients and made technical corrections and improvements to Topic 606. The standard, along with subsequent guidance from FASB, listed several items that are specifically out of scope for ASU 2014-09, including but not limited to core interest income, derivative instruments, investments, and loan origination fees. The Company adopted this standard on October 1, 2018 using the modified retrospective method. In addition, the Company prospectively changed the presentation of direct expenses associated with credit and debit card interchange income, which are now netted against interchange income in service charges and other fees in noninterest income on the consolidated statements of income, previously included in data processing and communication expense, and brokerage charges, which are now netted against wealth management fees in noninterest income on the consolidated statements of income, previously included in professional fees. The net quantitative impact of these presentation changes decreased both revenue and expenses by $6.6 million for the fiscal year ended September 30, 2019; however, these presentation changes did not have an impact on net income. Prior period balances have not been restated to reflect these presentation changes. There were no significant cumulative effect adjustments as a result of implementation as the current revenue recognition policies generally conform with the principals in ASC Topic 606. For additional information, see "Note 1. Nature of Operations and Summary of Significant Accounting Policies."

Restrictions on Cash and Cash E

Restrictions on Cash and Cash Equivalents	12 Months Ended
	Sep. 30, 2019
Cash and Cash Equivalents [Abstract]
Restrictions on Cash and Cash Equivalents	Restrictions on Cash and Cash EquivalentsThe Company is required to maintain reserve balances in cash and on deposit with the Federal Reserve based on a percentage of transactional deposits. The total requirement was approximately $51.2 million and $53.7 million at September 30, 2019 and 2018, respectively.

Securities Available for Sale

Securities Available for Sale	12 Months Ended
	Sep. 30, 2019
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 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 Amortized Gross Unrealized Gains Gross Unrealized Losses Estimated (dollars in thousands) As of September 30, 2018 U.S. Treasury securities $ 168,394 $ — $ (1,222) $ 167,172 Mortgage-backed securities: Government National Mortgage Association 442,458 35 (16,335) 426,158 Federal Home Loan Mortgage Corporation 297,380 — (7,055) 290,325 Federal National Mortgage Association 188,192 — (6,081) 182,111 Small Business Assistance Program 260,458 — (9,345) 251,113 States and political subdivision securities 69,566 4 (1,795) 67,775 Other 1,006 — (10) 996 Total $ 1,427,454 $ 39 $ (41,843) $ 1,385,650 The amortized cost and approximate fair value of debt securities available for sale as of September 30, 2019 and 2018, 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 any penalty. September 30, 2019 September 30, 2018 Amortized Estimated Amortized Estimated (dollars in thousands) Due in one year or less $ 58,377 $ 58,343 $ 111,842 $ 111,221 Due after one year through five years 89,836 90,601 114,920 113,069 Due after five years through ten years 12,110 12,324 11,076 10,535 Due after ten years — — 122 122 160,323 161,268 237,960 234,947 Mortgage-backed securities 1,603,955 1,620,903 1,188,488 1,149,707 Securities without contractual maturities 1,006 1,037 1,006 996 Total $ 1,765,284 $ 1,783,208 $ 1,427,454 $ 1,385,650 Proceeds from sales of securities available for sale were $175.0 million, $25.0 million and $5.1 million for the fiscal years ended September 30, 2019, 2018 and 2017 respectively. Gross gains (pre-tax) of $0.3 million, $0.0 million and $0.1 million were realized on the sales for the fiscal years ended September 30, 2019, 2018 and 2017, respectively, using the specific identification method. Gross losses (pre-tax) were $0.5 million, $0.0 million and $0.0 million for the fiscal years ended September 30, 2019, 2018 and 2017, respectively, using the specific identification method. The Company recognized no other-than-temporary impairment for the fiscal years ended September 30, 2019, 2018 and 2017. Securities with an estimated fair value of approximately $863.9 million and $787.4 million at September 30, 2019 and 2018, respectively, were pledged as collateral on public deposits, securities sold under agreements to repurchase, and for other purposes as required or permitted by 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 36% and 98% of the Company’s investment portfolio at September 30, 2019 and 2018, 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 that 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 September 30, 2019 or 2018. 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 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) Less than 12 months 12 months or more Total Estimated Unrealized Estimated Unrealized Estimated Unrealized (dollars in thousands) As of September 30, 2018 U.S. Treasury securities $ 167,172 $ (1,222) $ — $ — $ 167,172 $ (1,222) Mortgage-backed securities 416,677 (8,427) 709,387 (30,389) 1,126,064 (38,816) States and political subdivision securities 23,534 (250) 42,282 (1,545) 65,816 (1,795) Other 996 (10) — — 996 (10) Total $ 608,379 $ (9,909) $ 751,669 $ (31,934) $ 1,360,048 $ (41,843) As of September 30, 2019 and 2018, the Company had 169 and 390 securities, respectively, in an unrealized loss position.

Loans

Loans	12 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
Loans	Loans The following table presents the composition of net loans as of September 30, 2019 and 2018. September 30, 2019 2018 (dollars in thousands) Commercial real estate $ 5,092,410 $ 4,629,330 Agriculture 2,008,644 2,182,688 Commercial non-real estate 1,719,956 1,699,987 Residential real estate 812,208 837,569 Consumer 51,925 49,689 Other 47,541 46,487 Ending balance 9,732,684 9,445,750 Less: Unamortized discount on acquired loans (13,655) (18,283) Unearned net deferred fees and costs and loans in process (12,266) (11,543) Total $ 9,706,763 $ 9,415,924 The loan segments above include loans covered by a FDIC loss sharing agreement totaling $31.9 million and $42.6 million as of September 30, 2019 and 2018, respectively, residential real estate loans held for sale totaling $7.4 million and $5.5 million at September 30, 2019 and 2018, respectively, and $813.0 million and $865.4 million of loans accounted for at fair value as of September 30, 2019 and 2018, respectively. Unearned net deferred fees and costs totaled $13.9 million and $13.0 million as of September 30, 2019 and 2018, 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 $(1.6) million and $(1.5) million as of September 30, 2019 and 2018, respectively. Loans guaranteed by agencies of the U.S. government totaled $154.2 million and $168.6 million at September 30, 2019 and 2018, respectively. Principal balances of residential real estate loans sold totaled $288.1 million and $266.5 million for the fiscal years ended September 30, 2019 and 2018, respectively. Nonaccrual The following table presents the Company’s nonaccrual loans at September 30, 2019 and 2018, excluding ASC 310-30 loans. Loans greater than 90 days past due and still accruing interest as of September 30, 2019 and 2018 were $11.2 million and $0.2 million, respectively. September 30, 2019 2018 Nonaccrual loans (dollars in thousands) Commercial real estate $ 14,973 $ 22,871 Agriculture 77,880 107,198 Commercial non-real estate 9,502 6,887 Residential real estate 2,661 3,549 Consumer 74 61 Total $ 105,090 $ 140,566 Credit Quality Information The following table presents the composition of the loan portfolio by internally assigned grade as of September 30, 2019 and 2018. 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 $813.0 million for September 30, 2019 and $865.4 million for September 30, 2018. As of September 30, 2019 Commercial Real Estate Agriculture Commercial Residential Real Estate ¹ Consumer ¹ Other Total Credit Risk Profile by Internally Assigned Grade (dollars in thousands) 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. As of September 30, 2018 Commercial Real Estate Agriculture Commercial Residential Real Estate ¹ Consumer ¹ Other Total Credit Risk Profile by Internally Assigned Grade (dollars in thousands) Grade: Pass $ 4,108,314 $ 1,610,291 $ 1,401,418 $ 779,610 $ 48,979 $ 46,487 $ 7,995,099 Watchlist 53,150 239,392 19,503 4,548 322 — 316,915 Substandard 41,184 137,205 20,117 6,366 159 — 205,031 Doubtful 93 2 2,277 37 — — 2,409 Loss — — — — — — — Ending balance 4,202,741 1,986,890 1,443,315 790,561 49,460 46,487 8,519,454 Loans covered by a FDIC loss sharing agreement — — — 42,627 — — 42,627 Total $ 4,202,741 $ 1,986,890 $ 1,443,315 $ 833,188 $ 49,460 $ 46,487 $ 8,562,081 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 September 30, 2019 and 2018. 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 $813.0 million for September 30, 2019 and $865.4 million for September 30, 2018. 30-59 Days Past Due 60-89 Days Past Due 90 Days or Greater Past Due Total Current Total Financing Receivables As of September 30, 2019 (dollars in thousands) 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 30-59 Days Past Due 60-89 Days Past Due 90 Days or Greater Past Due Total Current Total Financing Receivables As of September 30, 2018 (dollars in thousands) Commercial real estate $ 920 $ 551 $ 9,135 $ 10,606 $ 4,192,135 $ 4,202,741 Agriculture 1,243 2,042 51,579 54,864 1,932,026 1,986,890 Commercial non-real estate 551 16 4,068 4,635 1,438,680 1,443,315 Residential real estate 913 200 1,747 2,860 787,701 790,561 Consumer 83 47 1 131 49,329 49,460 Other — — — — 46,487 46,487 Ending balance 3,710 2,856 66,530 73,096 8,446,358 8,519,454 Loans covered by a FDIC loss sharing agreement 30 233 471 734 41,893 42,627 Total $ 3,740 $ 3,089 $ 67,001 $ 73,830 $ 8,488,251 $ 8,562,081 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 $813.0 million for September 30, 2019 and $865.4 million for September 30, 2018. September 30, 2019 September 30, 2018 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance Related Allowance Impaired loans: (dollars in thousands) With an allowance recorded: Commercial real estate $ 26,003 $ 26,297 $ 4,159 $ 25,136 $ 25,223 $ 3,668 Agriculture 98,392 104,350 8,234 60,053 76,874 9,590 Commercial non-real estate 21,331 21,777 6,062 14,177 17,241 4,508 Residential real estate 3,829 4,311 1,795 4,509 5,153 2,210 Consumer 207 214 97 160 165 61 Total impaired loans with an allowance recorded 149,762 156,949 20,347 104,035 124,656 20,037 With no allowance recorded: Commercial real estate 28,272 66,631 — 15,764 58,141 — Agriculture 231,087 255,308 — 77,172 80,355 — Commercial non-real estate 21,579 31,414 — 8,905 18,047 — Residential real estate 3,290 5,454 — 2,177 4,574 — Consumer 1 108 — 1 118 — Total impaired loans with no allowance recorded 284,229 358,915 — 104,019 161,235 — Total impaired loans $ 433,991 $ 515,864 $ 20,347 $ 208,054 $ 285,891 $ 20,037 The following table presents the average recorded investment on impaired loans and interest income recognized on impaired loans for the fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Years Ended September 30, 2019 2018 2017 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 $ 42,374 $ 2,339 $ 54,434 $ 2,815 $ 42,347 $ 2,163 Agriculture 223,146 13,093 127,483 4,767 131,026 5,503 Commercial non-real estate 28,196 1,791 28,938 1,405 41,489 1,485 Residential real estate 6,889 410 7,156 452 8,900 453 Consumer 231 20 219 14 369 47 Total $ 300,836 $ 17,653 $ 218,230 $ 9,453 $ 224,131 $ 9,651 Valuation adjustments made to repossessed properties for the fiscal years ended September 30, 2019 and 2018, totaled $2.3 million and $1.6 million, 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 $10.3 million and $9.2 million at September 30, 2019 and 2018, respectively. There were $0.2 million of commitments to lend additional funds to borrowers whose loans were modified in a TDR as of September 30, 2019 and $0.3 million commitments to lend additional funds to borrowers whose loans were modified in a TDR as of September 30, 2018. The following table presents the recorded value of the Company’s TDR balances as of September 30, 2019 and 2018. September 30, 2019 September 30, 2018 Accruing Nonaccrual Accruing Nonaccrual (dollars in thousands) Commercial real estate $ 17,145 $ 904 $ 2,649 $ 2,616 Agriculture 22,929 24,762 13,248 73,741 Commercial non-real estate 4,398 4,257 3,420 656 Residential real estate 263 102 389 143 Consumer 107 48 77 — Total $ 44,842 $ 30,073 $ 19,783 $ 77,156 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 during the fiscal years ended September 30, 2019, 2018 and 2017. September 30, 2019 September 30, 2018 September 30, 2017 Recorded Investment Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Commercial real estate 2 $ 15,466 $ 15,466 1 $ 2,041 $ 2,041 2 $ 3,726 $ 3,726 Agriculture 16 11,537 11,537 5 10,753 10,753 13 18,902 18,902 Commercial non-real estate 2 1,445 1,445 — — — 9 2,044 2,044 Residential real estate — — — — — — 1 9 9 Consumer 2 188 188 1 73 73 1 8 8 Total accruing 22 $ 28,636 $ 28,636 7 $ 12,867 $ 12,867 26 $ 24,689 $ 24,689 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 during the fiscal years ended September 30, 2019, 2018 and 2017. September 30, 2019 September 30, 2018 September 30, 2017 Recorded Investment Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Commercial real estate 1 $ 882 $ 882 — $ — $ — — $ — $ — Agriculture 9 5,802 5,802 9 9,990 9,990 18 20,197 20,197 Commercial non-real estate 2 3,699 3,699 — — — 3 3,788 3,788 Residential real estate — — — — — — 2 133 133 Consumer — — — — — — 3 21 21 Total nonaccruing 12 $ 10,383 $ 10,383 9 $ 9,990 $ 9,990 26 $ 24,139 $ 24,139 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 fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Years Ended September 30, 2019 2018 2017 Number of Loans Recorded Investment Number of Loans Recorded Investment Number of Loans Recorded Investment (dollars in thousands) Commercial real estate — $ — — $ — — $ — Agriculture — — 1 366 2 8,383 Commercial non-real estate — — — — 1 — Residential real estate — — — — — — Consumer 1 — — — — — Total 1 $ — 1 $ 366 3 $ 8,383 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 $0.0 million, $0.8 million and $5.5 million as of September 30, 2019, 2018 and 2017, 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	12 Months Ended
	Sep. 30, 2019
Loans and Leases Receivable Disclosure [Abstract]
Allowance for Loan and Lease Losses	Allowance for Loan and Lease Losses The following tables present the Company’s allowance for loan and lease losses roll forward for the fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Year Ended September 30, 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 (1,511) (24,847) (7,895) (998) (452) (1,358) (37,061) Recoveries 567 385 392 468 174 362 2,348 Provision 1,514 27,160 11,431 (56) 448 1,009 41,506 (Improvement) impairment of ASC 310-30 loans (520) — 29 (68) — — (559) Ending balance, September 30, 2019 $ 16,827 $ 30,819 $ 17,567 $ 4,095 $ 427 $ 1,039 $ 70,774 Fiscal Year Ended September 30, 2018 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Beginning balance, October 1, 2017 $ 16,941 $ 25,757 $ 14,114 $ 5,347 $ 329 $ 1,015 $ 63,503 Charge-offs (3,925) (9,473) (3,813) (569) (192) (1,932) (19,904) Recoveries 533 332 994 337 141 618 2,955 Provision 3,231 11,355 2,315 (451) (21) 1,325 17,754 (Improvement) impairment of ASC 310-30 loans (3) 150 — 85 — — 232 Ending balance, September 30, 2018 $ 16,777 $ 28,121 $ 13,610 $ 4,749 $ 257 $ 1,026 $ 64,540 Fiscal Year Ended September 30, 2017 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Beginning balance, October 1, 2016 $ 17,946 $ 25,115 $ 12,990 $ 7,106 $ 438 $ 1,047 $ 64,642 Charge-offs (2,043) (7,853) (12,576) (809) (196) (2,403) (25,880) Recoveries 485 415 652 507 102 1,041 3,202 Provision 643 7,965 13,048 (761) (15) 1,330 22,210 (Improvement) impairment of ASC 310-30 loans (90) 115 — (696) — — (671) Ending balance, September 30, 2017 $ 16,941 $ 25,757 $ 14,114 $ 5,347 $ 329 $ 1,015 $ 63,503 The following tables provide details regarding the allowance for loan and lease losses and balance by type of allowance as of September 30, 2019 and 2018. These tables are presented net of unamortized discount on acquired loans and excludes loans of $813.0 million measured at fair value, loans held for sale of $7.4 million, and guaranteed loans of $145.9 million for September 30, 2019; and loans measured at fair value of $865.4 million, loans held for sale of $5.5 million, and guaranteed loans of $160.3 million for September 30, 2018. 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 As of September 30, 2018 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 $ 3,668 $ 9,590 $ 4,508 $ 2,210 $ 61 $ — $ 20,037 Collectively evaluated for impairment 12,430 18,266 9,102 2,277 196 1,026 43,297 ASC 310-30 loans 679 265 — 262 — — 1,206 Total allowance $ 16,777 $ 28,121 $ 13,610 $ 4,749 $ 257 $ 1,026 $ 64,540 Financing Receivables Individually evaluated for impairment $ 40,900 $ 137,225 $ 23,082 $ 6,686 $ 161 $ — $ 208,054 Collectively evaluated for impairment 4,053,712 1,823,947 1,364,511 780,047 48,711 46,487 8,117,415 ASC 310-30 loans 27,001 2,815 416 40,025 588 — 70,845 Loans Outstanding $ 4,121,613 $ 1,963,987 $ 1,388,009 $ 826,758 $ 49,460 $ 46,487 $ 8,396,314 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 $0.6 million at September 30, 2019, compared to $1.2 million at September 30, 2018. During fiscal year 2019, loan pools accounted for under ASC 310-30 had a net reversal of provision of $0.6 million, a net provision of $0.2 million for fiscal year 2018 and a net provision reversal of $0.7 million for fiscal year 2017. The reserve for unfunded loan commitments was $0.5 million at both September 30, 2019 and 2018 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	12 Months Ended
	Sep. 30, 2019
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 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 fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Balance, beginning of period $ 34,973 $ 44,131 $ 38,124 Accretion (9,202) (13,193) (13,847) Reclassification from nonaccretable difference 276 4,035 19,854 Balance, end of period $ 26,047 $ 34,973 $ 44,131 The reclassifications 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 impaired loans at September 30, 2019 and 2018. September 30, 2019 September 30, 2018 Outstanding Balance ¹ Recorded Investment ² Carrying Value ³ Outstanding Balance ¹ Recorded Investment ² Carrying Value ³ (dollars in thousands) Commercial real estate $ 90,295 $ 22,124 $ 21,965 $ 100,761 $ 27,001 $ 26,322 Agriculture 4,462 2,756 2,491 4,841 2,815 2,551 Commercial non-real estate 7,190 221 192 7,475 416 416 Residential real estate 35,413 30,280 30,168 46,646 40,025 39,763 Consumer 493 438 438 656 588 588 Total lending $ 137,853 $ 55,819 $ 55,254 $ 160,379 $ 70,845 $ 69,640 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	12 Months Ended
	Sep. 30, 2019
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 fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Balance, beginning of period $ 2,502 $ 5,704 $ 10,777 Amortization (1,386) (2,778) (4,748) Changes in expected reimbursements from FDIC for changes in expected credit losses (10) (122) (45) Changes in reimbursable expenses (41) (1,072) (986) Payments of covered losses to the FDIC 14 770 706 Balance, end of period $ 1,079 $ 2,502 $ 5,704 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.

Premises and Equipment

Premises and Equipment	12 Months Ended
	Sep. 30, 2019
Property, Plant and Equipment [Abstract]
Premises and Equipment	Premises and Equipment The following table presents the major classes of premises and equipment and the total amount of accumulated depreciation as of September 30, 2019 and 2018. September 30, 2019 2018 (dollars in thousands) Land $ 31,107 $ 25,598 Buildings and building improvements 95,778 85,960 Furniture and equipment 26,688 27,490 Construction in progress 3,619 7,732 Total 157,192 146,780 Accumulated depreciation (36,547) (32,941) Premise and equipment, net $ 120,645 $ 113,839 Depreciation expense was $7.6 million, $7.5 million and $7.6 million for the fiscal years ended September 30, 2019, 2018 and 2017, respectively. Included in the premises and equipment is $2.8 million and $1.1 million of property held for sale as of September 30, 2019 and 2018, respectively. The Company measures assets held for sale at the lower of carrying amount or estimated fair value. There were no impairment charges recognized as of September 30, 2019 and 2018.

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments The Company uses interest rate swaps to manage its interest rate risk and market risk in accommodating the needs of its customers. 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 September 30, 2019 and 2018. September 30, 2019 September 30, 2018 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 $ 1,259,765 $ 35 $ (38,755) $ 1,082,630 $ 22,696 $ (2,231) Customer counterparties 499,643 48,652 — 217,066 1,533 (2,160) Interest rate caps Financial institution counterparties 100 2 — — — — Customer counterparties 100 — (2) — — — Risk participation agreements 56,833 — (58) 37,351 — (444) Mortgage loan commitments 56,665 — (11) 22,195 — (28) Mortgage loan forward sale contracts 61,872 11 — 27,408 28 — Total $ 1,934,978 $ 48,700 $ (38,826) $ 1,386,650 $ 24,257 $ (4,863) 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 September 30, 2019 and 2018. 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. Gross Fair Value Fair Value Offset Amount Cash Collateral Net Amount Presented on the Consolidated Balance Sheet (dollars in thousands) As of September 30, 2018 Total Derivative Assets $ 24,257 $ (2,231) $ (20,115) $ 1,911 Total Derivative Liabilities ¹ $ (4,863) $ 2,231 $ — $ (2,632) 1 There was an additional $6.2 million of collateral held for initial margin with a Futures Clearing Merchant for clearing derivatives at September 30, 2018 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 counterparty 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. Beginning in the second quarter of fiscal year 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 notional amounts of RPAs sold were $56.8 million and $37.4 million as of September 30, 2019 and 2018, respectively. Assuming all underlying loan customers defaulted on their obligation to perform under the interest rate swap with a derivative counterparty, the exposure from these RPAs would be $0.1 million and $0.4 million at September 30, 2019 and 2018, respectively, based on the fair value of the underlying swaps. The effect of derivatives on the consolidated statements of income for the fiscal years ended September 30, 2019, 2018 and 2017 was as follows. Amount of (Loss) Gain Recognized in Consolidated Statements of Income Fiscal Years Ended September 30, Derivatives not designated as hedging instruments: Location of (Loss) Gain Recognized in Consolidated Statements of Income 2019 2018 2017 (dollars in thousands) Interest rate swaps and other derivatives Net realized and unrealized (loss) gain on derivatives $ (63,444) $ 44,596 $ 49,900 Mortgage loan commitments Net realized and unrealized (loss) gain on derivatives 17 (28) (48) Mortgage loan forward sale contracts Net realized and unrealized (loss) gain on derivatives (17) 28 48

The Fair Value Option For Certa

The Fair Value Option For Certain Loans	12 Months Ended
	Sep. 30, 2019
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 24 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 $34.2 million at September 30, 2019 and a net unfavorable difference of approximately $34.8 million at September 30, 2018. The total unpaid principal balance of these long-term loans was approximately $778.8 million and $900.2 million at September 30, 2019 and 2018, 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 5. As of September 30, 2019 and 2018, there were loans with a fair value of $16.5 million and $30.9 million, respectively, which were greater than 90 days past due or in nonaccrual status with an unpaid principal balance of $17.8 million and $34.7 million, respectively. Changes in fair value for items for which the fair value option has been elected were an increase in fair value of $61.4 million for the fiscal year ended September 30, 2019 and decreases in fair value of $45.4 million and $65.2 million for the fiscal years ended September 30, 2018 and 2017, respectively. These changes in fair value are reported in noninterest income (loss) within the consolidated statements of income. For long-term loans at September 30, 2019, 2018 and 2017, approximately $7.7 million, $0.2 million and $0.9 million, 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	12 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	GoodwillThe Company's carrying amount of goodwill was $739.0 million for the fiscal years ended September 30, 2019 and 2018, respectively. 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. See "Note 1. Nature of Operations and Summary of Significant Accounting Policies," for additional information regarding the Company's goodwill accounting policy. For the fiscal years ended September 30, 2019, 2018 and 2017, the Company did not recognize any impairment related to goodwill.

Core Deposits and Other Intangi

Core Deposits and Other Intangibles	12 Months Ended
	Sep. 30, 2019
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 September 30, 2019 and 2018. Core Deposit Intangible Brand Other Total (dollars in thousands) 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 As of September 30, 2018 Gross carrying amount $ 7,339 $ 8,464 $ 538 $ 16,341 Accumulated amortization (2,610) (5,828) (191) (8,629) Net intangible assets $ 4,729 $ 2,636 $ 347 $ 7,712 Amortization expense of intangible assets was $1.5 million, $1.7 million and $2.4 million for the fiscal years ended September 30, 2019, 2018 and 2017, respectively. 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) 2020 $ 1,430 2021 1,334 2022 1,249 2023 967 2024 498 2025 and thereafter 696 Total $ 6,174

Deposits

Deposits	12 Months Ended
	Sep. 30, 2019
Banking and Thrift [Abstract]
Deposits	Deposits The following table presents the composition of deposits as of September 30, 2019 and 2018. September 30, 2019 2018 (dollars in thousands) Noninterest-bearing demand $ 1,956,025 $ 1,842,704 Interest-bearing demand 6,248,638 6,043,717 Time deposits, greater than $250,000 493,530 383,868 Time deposits, less than or equal to $250,000 1,602,146 1,463,210 Total $ 10,300,339 $ 9,733,499 At September 30, 2019 and 2018, the Company had $706.5 million and $600.2 million, respectively, in brokered deposits. As a result of the passage of the Economic Growth, Regulatory Relief and Consumer Protection Act in May 2018, most reciprocal deposits are no longer treated as brokered deposits and are now included with core commercial deposits. At September 30, 2019, the following table presents the scheduled maturities of time deposits in subsequent fiscal years. Accounts with no stated maturity date are included in 2020. Fiscal year Amount (dollars in thousands) 2020 $ 1,746,896 2021 250,248 2022 60,337 2023 26,858 2024 11,026 2025 and thereafter 311 Total $ 2,095,676

Securities Sold Under Agreement

Securities Sold Under Agreements to Repurchase	12 Months Ended
	Sep. 30, 2019
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities Sold Under Agreements to Repurchase	Securities Sold Under Agreements to RepurchaseSecurities sold under agreements to repurchase generally mature overnight following the transaction date. Securities underlying the agreements had an amortized cost of approximately $94.7 million and $109.9 million and fair value of approximately $94.4 million and $104.6 million at September 30, 2019 and 2018, respectively. In most cases, in alignment with the repurchase agreements in place with customers, the Company over-collateralizes the repurchase 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 September 30, 2019 and 2018. 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 September 30, 2018 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 $ 90,907 $ — $ — $ — $ 90,907 Total repurchase agreements $ 90,907 $ — $ — $ — $ 90,907

FHLB Advances and Other Borrowi

FHLB Advances and Other Borrowings	12 Months Ended
	Sep. 30, 2019
Federal Home Loan Banks [Abstract]
FHLB Advances and Other Borrowings	FHLB Advances and Other Borrowings The following table presents the FHLB advances and other borrowings consist of the following at September 30, 2019 and 2018. September 30, 2019 2018 (dollars in thousands) Short-term borrowings: FHLB fed funds advance, interest rate of 2.09%, matured in October 2019 $ 15,000 $ 100,000 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 325,000 175,000 Total FHLB advances and other borrowings $ 340,000 $ 275,000 As of September 30, 2019 and 2018, the Company had a borrowing capacity of $1.44 billion and $1.59 billion, respectively, with the FRB Discount Window. Principal balances of loans pledged to FRB Discount Window to collateralize the borrowing totaled $1.72 billion at September 30, 2019 and $1.89 billion at September 30, 2018. The Company has secured this line for contingency funding. As of September 30, 2019 and 2018, based its collateral pledged, the additional borrowing capacity of the Company with the FHLB was $1.80 billion and $1.82 billion, respectively. Principal balances of loans pledged to the FHLB to collateralize notes payable totaled $4.20 billion and $3.95 billion at September 30, 2019 and 2018, respectively. The Company purchased letters of credit from the FHLB to pledge as collateral on public deposits. The amount outstanding was $170.0 million and $150.0 million at September 30, 2019 and 2018, respectively. The Company had additional letters of credit from the FHLB of $14.9 million and $16.4 million at September 30, 2019 and 2018, respectively, for other purposes. As of September 30, 2019, FHLB advances and other borrowings are due or callable (whichever is earlier) in subsequent fiscal years as follows. Fiscal year Amount (dollars in thousands) 2020 $ 15,000 2021 120,000 2022 60,000 2023 85,000 2024 60,000 2025 and thereafter — Total $ 340,000

Subordinated Debentures and Sub

Subordinated Debentures and Subordinated Notes Payable	12 Months Ended
	Sep. 30, 2019
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 September 30, 2019 have issued Company Obligated Mandatorily Redeemable Preferred Securities ("Preferred Securities"). These trusts are described herein. The sole assets of the trusts are junior subordinated deferrable interest debentures ("Debentures") issued by the Company, or assumed as part of the HF Financial and Sunstate Bank acquisitions, with interest, maturity, and distribution provisions similar in term to the respective Preferred Securities. Additionally, to the extent interest payments are deferred on the Debentures, payment on the Preferred Securities will be deferred for the same period. 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 September 30, 2019 and 2018, $73.7 million and $73.6 million, respectively, of Debentures, net of fair value adjustment, were eligible for treatment as Tier 1 capital. The Company caused to be issued 22,400 shares, $1,000 par value, of Preferred Securities of Great Western Statutory Trust IV on December 17, 2003, through a private placement. The distribution rate is set quarterly at three month LIBOR plus 285 basis points. Interest Payment Dates are March 17, June 17, September 17 and December 17 of each year, beginning March 17, 2004 and are payable in arrears. The Company may, at one or more times, defer interest payments on the related Debentures for up to 20 consecutive quarters following suspension of dividends on all capital stock. At the end of any deferral period, all accumulated and unpaid distributions must be paid. The Debentures will be redeemed 30 years from the issuance date; however, subject to the Company receiving prior approval of the Federal Reserve, if required, the Company has the right to redeem the Debentures in whole, but not in part, at the Special Redemption Date, at a premium as defined by the Indenture if a "Special Event" occurs prior to December 17, 2008. A "Special Event" means any Capital Treatment Event, an Investment Company Event, or a Tax Event. On or after December 17, 2008, subject to the Company receiving prior approval of the Federal Reserve, if required, the Company has the right to redeem the Debentures at the Redemption Price, in whole or in part, on an Interest Payment Date. The Redemption Price is $1,000 per Preferred Security plus any accrued and unpaid distributions to the date of redemption. Holders of the Preferred Securities have no voting rights. The Preferred Securities are unsecured and rank junior in priority of payment to all of the Company’s senior indebtedness and senior to the Company’s common and preferred stock. Proceeds from the issue were used for general corporate purposes. The Company caused to be issued 30,000 shares, $1,000 par value, of Preferred Securities of GWB Capital Trust VI on March 10, 2006, through a private placement. The distribution rate is set quarterly at three month LIBOR plus 148 basis points. Interest Payment dates are December 15, March 15, June 15, and September 15 of each year, beginning June 15, 2006, and are payable in arrears. The Company may, at one or more times, defer interest payments on the related Debentures for up to 20 consecutive quarters following suspension of dividends on all capital stock. At the end of any deferral period, all accumulated and unpaid interest must be paid. The Debentures will be redeemed March 15, 2036; however, subject to the Company receiving prior approval of the Federal Reserve, if required, the Company has the right to redeem the Debentures in whole, but not in part, at any Interest Payment Date, at a premium as defined by the Indenture if a "Special Event" occurs prior to March 15, 2007. A "Special Event" means any Capital Treatment Event, an Investment Company Event, or a Tax Event. On or after March 15, 2011, subject to the Company receiving approval of the Federal Reserve, if required, the Company has the right to redeem the Debentures at the Redemption Price, in whole or in part, on an Interest Payment Date. The Redemption Price is $1,000 per Preferred Security plus any accrued and unpaid interest to the date of redemption. Holders of the Preferred Securities have no voting rights. The Preferred Securities are unsecured and rank junior in priority of payment to all of the Company’s senior indebtedness and senior to the Company’s common and preferred stock. Proceeds from the issue were used for general corporate purposes including redemption of the 9.75% Preferred Securities of GWB Capital Trust II. The Company acquired the Sunstate Bancshares Trust II in the acquisition of Sunstate Bank. Sunstate Bancshares caused to be issued 2,000 shares, $1,000 par value, of Preferred Securities of Sunstate Bancshares Trust II on June 1, 2005, through a private placement. The distribution rate is set quarterly at three month LIBOR plus 185 basis points. Interest Payment dates are March 15, June 15, September 15, and December 15 of each year, beginning September 15, 2005, and are payable in arrears. The Company may, at one or more times, defer interest payments on the related Debentures for up to 20 consecutive quarters following suspension of dividends on all capital stock. At the end of any deferral period, all accumulated and unpaid interest must be paid. The Debentures will be redeemed June 15, 2035; however, subject to the Company receiving prior approval of the Federal Reserve, if required, the Company has the right to redeem the Debentures, in whole or in part, at any time, within 90 days following the occurrence of a Special Event, at a premium as defined by the Indenture if a "Special Event" occurs prior to June 15, 2010. A "Special Event" means any Capital Treatment Event, an Investment Company Event, or a Tax Event. On or after June 15, 2010, subject to the Company receiving prior approval of the Federal Reserve, if required, the Company has the right to redeem the Debentures at the Redemption Price, in whole or in part, on an Interest Payment Date. The Redemption Price is $1,000 per Preferred Security plus any accrued and unpaid interest to the date of redemption. Holders of the Preferred Securities have no voting rights. The Preferred Securities are unsecured and rank junior in priority of payment to all of the Company’s senior indebtedness and senior to the Company’s common and preferred stock. The Company acquired the HFB Trust III in the acquisition of HF Financial. HF Financial Corp. caused to be issued 5,000 shares, $1,000 par value, of Preferred Securities of HFB Trust III on December 19, 2002, through a private placement. The distribution rate is set quarterly at three month LIBOR plus 335 basis points. Interest Payment dates are January 7, April 7, July 7, and October 7 of each year, beginning April 7, 2003, and are payable in arrears. The Company may, at one or more times, defer interest payments on the related Debentures for up to 20 consecutive quarters following suspension of dividends on all capital stock. At the end of any deferral period, all accumulated and unpaid interest must be paid. The Debentures will be redeemed January 7, 2033; however, subject to the Company receiving prior approval of the Federal Reserve, if required, the Company has the right to redeem the Debentures, in whole or in part, at any time, within 90 days following the occurrence of a Special Event, at a premium as defined by the Indenture if a "Special Event" occurs prior to January 7, 2008. A "Special Event" means any Capital Treatment Event, an Investment Company Event, or a Tax Event. On or after January 7, 2008, subject to the Company receiving prior approval of the Federal Reserve, if required, the Company has the right to redeem the Debentures at the Redemption Price, in whole or in part, on an Interest Payment Date. The Redemption Price is $1,000 per Preferred Security plus any accrued and unpaid interest to the date of redemption. Holders of the Preferred Securities have no voting rights. The Preferred Securities are unsecured and rank junior in priority of payment to all of the Company’s senior indebtedness and senior to the Company’s common and preferred stock. The Company acquired the HFB Trust IV in the acquisition of HF Financial. HF Financial Corp. caused to be issued 7,000 shares, $1,000 par value, of Preferred Securities of HFB Trust IV on September 25, 2003, through a private placement. The distribution rate is set quarterly at three month LIBOR plus 310 basis points. Interest Payment dates are January 8, April 8, July 8, and October 8 of each year, beginning January 8, 2004, and are payable in arrears. The Company may, at one or more times, defer interest payments on the related Debentures for up to 20 consecutive quarters following suspension of dividends on all capital stock. At the end of any deferral period, all accumulated and unpaid interest must be paid. The Debentures will be redeemed October 8, 2033; however, subject to the Company receiving prior approval of the Federal Reserve, if required, the Company has the right to redeem the Debentures in whole or in part, at any time, within 90 days following the occurrence of a Special Event, at a premium as defined by the Indenture if a "Special Event" occurs prior to October 8, 2008. A "Special Event" means any Capital Treatment Event, an Investment Company Event, or a Tax Event. On or after October 8, 2008, subject to the Company receiving prior approval of the Federal Reserve, if required, the Company has the right to redeem the Debentures at the Redemption Price, in whole or in part, on an Interest Payment Date. The Redemption Price is $1,000 per Preferred Security plus any accrued and unpaid interest to the date of redemption. Holders of the Preferred Securities have no voting rights. The Preferred Securities are unsecured and rank junior in priority of payment to all of the Company’s senior indebtedness and senior to the Company’s common and preferred stock. The Company acquired the HFB Trust V in the acquisition of HF Financial. HF Financial Corp. caused to be issued 10,000 shares, $1,000 par value, of Preferred Securities of HFB Trust V on December 7, 2006, through a private placement. The distribution rate is set quarterly at three month LIBOR plus 183 basis points. Interest Payment dates are March 1, June 1, September 1, and December 1 of each year, beginning March 1, 2007, and are payable in arrears. The Company may, at one or more times, defer interest payments on the related Debentures for up to 20 consecutive quarters following suspension of dividends on all capital stock. At the end of any deferral period, all accumulated and unpaid interest must be paid. The Debentures will be redeemed March 1, 2037; however, subject to the Company receiving prior approval of the Federal Reserve, if required, the Company has the right to redeem the Debentures, in whole or in part, at any time, within 90 days following the occurrence of a Special Event, at a premium as defined by the Indenture if a "Special Event" occurs prior to March 1, 2012. A "Special Event" means any Capital Treatment Event, an Investment Company Event, or a Tax Event. On or after March 1, 2012, subject to the Company receiving prior approval of the Federal Reserve, if required, the Company has the right to redeem the Debentures at the Redemption Price, in whole or in part, on an Interest Payment Date. The Redemption Price is $1,000 per Preferred Security plus any accrued and unpaid interest to the date of redemption. Holders of the Preferred Securities have no voting rights. The Preferred Securities are unsecured and rank junior in priority of payment to all of the Company’s senior indebtedness and senior to the Company’s common and preferred stock. In the first quarter of fiscal year 2017, the Company redeemed 5,000 shares of HF Trust V Debentures under the first Supplemental Indenture dated May 13, 2016. The Company acquired the HFB Trust VI in the acquisition of HF Financial. HF Financial Corp. caused to be issued 2,000 shares, $1,000 par value, of Preferred Securities of HFB Trust VI on July 5, 2007, through a private placement. The distribution rate is set quarterly at three month LIBOR plus 165 basis points. Interest Payment dates are January 1, April 1, July 1, and October 1 of each year, beginning October 1, 2007, and are payable in arrears. The Company may, at one or more times, defer interest payments on the related Debentures for up to 20 consecutive quarters following suspension of dividends on all capital stock. At the end of any deferral period, all accumulated and unpaid interest must be paid. The Debentures will be redeemed October 1, 2037; however, subject to the Company receiving prior approval of the Federal Reserve, if required, the Company has the right to redeem the Debentures, in whole or in part, at any time, within 90 days following the occurrence of a "Special Event", at a premium as defined by the Indenture if a "Special Event" occurs prior to October 1, 2012. A "Special Event" means any Capital Treatment Event, an Investment Company Event, or a Tax Event. On or after October 1, 2012, subject to the Company receiving prior approval of the Federal Reserve, if required, the Company has the right to redeem the Debentures at the Redemption Price, in whole or in part, on an Interest Payment Date. The Redemption Price is $1,000 per Preferred Security plus any accrued and unpaid interest to the date of redemption. Holders of the Preferred Securities have no voting rights. The Preferred Securities are unsecured and rank junior in priority of payment to all of the Company’s senior indebtedness and senior to the Company’s common and preferred stock. Relating to the trusts, the Company held as assets $2.5 million in common shares at September 30, 2019 and 2018, 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 September 30, 2019, have an interest rate of 4.875% per annum, payable semi-annually on each February 15 and August 15, which commenced 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 in the event of bankruptcy or the occurrence of certain other events of bankruptcy, insolvency or reorganization. Unamortized debt issuance costs related to these notes, which are included in Subordinated Debentures and Subordinated Notes Payable, totaled $0.1 million at both September 30, 2019 and 2018. Proceeds from the private placement of subordinated notes repaid outstanding subordinated debt. The following table presents the subordinated debentures and subordinated notes payable at September 30, 2019 and 2018. September 30, 2019 September 30, 2018 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 (2,223) (2,317) Total junior subordinated debentures payable, net of fair value adjustment 73,697 73,603 Subordinated notes payable Fixed to floating rate, 4.875% per annum 35,000 35,000 Less: unamortized debt issuance costs (61) (135) Total subordinated notes payable 34,939 34,865 Total subordinated debentures and subordinated notes payable $ 108,636 $ 108,468 1 Adjustment reflects the fair value adjustments related to the junior subordinated deferrable interest debentures assumed as part of the HF Financial acquisition.

Income Taxes

Income Taxes	12 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The provision for income taxes charged to operations consists of the following for the fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Currently paid or payable Federal $ 30,779 $ 42,261 $ 56,171 State 9,327 10,556 10,639 Total 40,106 52,817 66,810 Deferred tax expense Federal 7,507 20,205 2,477 State 617 1,097 154 Total 8,124 21,302 2,631 Total provision for income taxes $ 48,230 $ 74,119 $ 69,441 The income tax provision differs from the amount of income tax determined by applying a U.S. federal income tax rate of 21.0% for fiscal year 2019, a blended U.S. federal income tax rate of 24.5% for fiscal year 2018 and a U.S. federal income tax rate of 35.0% for fiscal year 2017 to pretax income due to the following. Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Income tax expense computed at the statutory rate $ 45,275 $ 56,915 $ 74,979 Increase (decrease) in income taxes resulting from: State income taxes, net of federal benefit 7,855 8,795 7,015 Tax exempt interest income (5,193) (5,778) (7,973) Tax benefit of stock-based compensation plans (91) (424) (2,153) Impact of enacted federal income tax rate reduction — 13,709 — Other 384 902 (2,427) Income tax expense, as reported $ 48,230 $ 74,119 $ 69,441 Net deferred tax assets (liabilities) consist of the following components at September 30, 2019 and 2018. September 30, 2019 2018 (dollars in thousands) Deferred tax assets: Allowance for loan and lease losses $ 17,214 $ 15,709 Compensation 4,017 2,577 Securities available for sale — 10,305 Other real estate owned 574 325 Core deposit intangible and other fair value adjustments 3,868 3,677 Excess tax basis of FDIC indemnification asset and clawback liability 4,095 3,633 Excess tax basis of loans acquired over carrying value 2,656 3,669 Other reserves 2,926 2,787 Other 6,350 5,711 Total deferred tax assets 41,700 48,393 Deferred tax liabilities: Goodwill and other intangibles (15,064) (11,567) Securities available for sale (4,419) — Premises and equipment (5,869) (6,248) Deferred REIT income (8,783) — Other (279) (446) Total deferred tax liabilities (34,414) (18,261) Net deferred tax assets $ 7,286 $ 30,132 At September 30, 2019 and 2018, the Company had an income tax receivable from the IRS of $8.4 million and $3.5 million, respectively, which is included in other assets on the consolidated balance sheets. The Company is no longer subject to U.S. federal, state and local or non-U.S. income tax examinations by tax authorities for years before 2015. On December 22, 2017, the Tax Reform Act was enacted into law. Beginning in 2018, the Tax Reform Act reduced the federal tax rate for corporations from 35% to 21% and changed or limited certain tax deductions. Because of the Company's September 30 fiscal year end, a blended statutory rate of 24.5% was applied to all net income before taxes generated during fiscal year 2018 . The new blended statutory rate reduced the provision for income taxes by approximately $19.7 million for the fiscal year ended September 30, 2018. Another result of the lower corporate tax rate was the Company's recording of a $13.6 million revaluation adjustment in the first quarter of fiscal year 2018, reducing net deferred tax assets and increasing the provision for income taxes. Differences between the actual impact of revaluing deferred taxes for the full fiscal year and the preliminary estimate were immaterial. The Company adopted new accounting guidance in the second quarter of fiscal year 2018 that allowed reclassification of $2.4 million in stranded tax effects that related to a change in the federal tax rate from accumulated other comprehensive income to retained earnings. The Bank's effective tax rate for the fiscal years ended September 30, 2019 and 2018 was 22.4% and 31.9%, respectively. Excluding the nonrecurring deferred taxes adjustment related to federal tax reform, the effective tax rate for September 30, 2019 and 2018 were 22.4% and 26.1%, respectively. Management has determined a valuation reserve is not required for the deferred tax assets as of September 30, 2019 and 2018 because it is more-likely-than-not these assets could be realized through future reversals of existing taxable temporary differences, and future taxable income. Uncertain tax positions were not significant at September 30, 2019 or 2018.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Sep. 30, 2019
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans Profit Sharing Plan The 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

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Sep. 30, 2019
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. For the fiscal years ended September 30, 2019, 2018 and 2017 stock compensation expense was $5.9 million, $5.5 million and $6.5 million respectively. Related income tax benefits recognized for the fiscal years ended September 30, 2019, 2018 and 2017 were $1.5 million, $1.7 million and $2.5 million, respectively. The following is a summary of the Plans’ restricted share and performance-based stock award activity as of September 30, 2019 and 2018. The number of performance shares granted in the following table are reflected at the amount of achievement of the pre-established targets. September 30, 2019 September 30, 2018 September 30, 2017 Common Weighted-Average Grant Date Fair Value Common Weighted-Average Grant Date Fair Value Common Weighted-Average Grant Date Fair Value Restricted Shares Restricted shares, beginning of fiscal year 163,287 $ 37.86 180,337 $ 33.06 160,335 $ 26.89 Granted 106,753 37.27 89,376 41.07 90,363 39.35 Vested (76,210) 38.64 (97,682) 32.11 (68,293) 26.97 Forfeited (3,025) 38.67 (8,744) 35.99 (2,068) 30.91 Canceled — — — — — — Restricted shares, end of period 190,805 $ 37.20 163,287 $ 37.86 180,337 $ 33.06 Vested, but not issuable at end of period 50,770 $ 33.88 39,514 $ 32.90 29,287 $ 30.05 Performance Shares Performance shares, beginning of fiscal year 175,196 $ 36.29 133,604 $ 33.39 236,185 $ 20.28 Granted 60,583 32.77 53,682 29.52 137,612 39.43 Vested (59,937) 30.79 (7,017) 18.00 (235,055) 18.00 Forfeited (2,510) 39.25 (5,073) 37.75 (5,138) 19.80 Canceled — — — — — — Performance shares, end of period 173,332 $ 38.50 175,196 $ 36.29 133,604 $ 33.39 Vested, but not issuable at end of period 5,612 $ 18.00 5,612 $ 18.00 5,612 $ 18.00 As of September 30, 2019, there was $5.0 million of unrecognized compensation cost related to non-vested restricted stock awards expected to be recognized over a period of 2.2 years. The fair value of the vested awards was $1.9 million at both September 30, 2019 and 2018 and $1.4 million at September 30, 2017.

Regulatory Matters

Regulatory Matters	12 Months Ended
	Sep. 30, 2019
Banking and Thrift [Abstract]
Regulatory Matters	Regulatory MattersThe Company and the Bank are subject to various regulatory capital requirements administered by the federal banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on the Company’s and the Bank’s financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Company and the Bank must meet specific capital guidelines that involve quantitative measures of the Company’s and the Bank’s assets, liabilities, and certain off-balance sheet items as calculated under regulatory accounting practices. The Company’s and the Bank’s capital amounts and classifications are also subject to qualitative judgments by the regulators about components, risk weightings, and other factors. On January 1, 2015, the Company became subject to Basel III rules, which included transition provisions through January 1, 2019. The minimum capital level requirements applicable to the Company are: (i) a Tier 1 capital ratio of 6.0%; (ii) a total capital ratio of 8.0%; (iii) a Tier 1 leverage capital ratio of 4.0%; and (iv) a common equity Tier 1 capital ratio of 4.5%. The rules also established a "capital conservation buffer" of 2.5% above the minimum capital requirements, which must consist entirely of common equity Tier 1 capital and results in the following minimum ratios: (i) a Tier 1 capital ratio of 8.5%; (ii) a total capital ratio of 10.5%; and (iii) a common equity Tier 1 capital ratio of 7.0%. The capital conservation buffer requirement was phased in beginning in January 2016 at 0.625% of risk-weighted assets and increased by that amount each year until fully implemented in January 2019. An institution is subject to limitations on paying dividends, engaging in share repurchases, and paying discretionary bonuses if its capital level falls below the buffer amount. These limitations establish a maximum percentage of eligible retained income that could be utilized for such actions. The Company met all capital adequacy and net worth requirements to which they are subject as of September 30, 2019 and 2018. As of September 30, 2019, the most recent notification from the regulatory agencies categorized the Bank as well capitalized under the regulatory framework for prompt corrective action. To be categorized as well-capitalized, the institution must maintain minimum total risk-based, Tier 1 risk-based, and Tier 1 leverage ratios as set forth in the following table. There are no conditions or events since the most recent notification that management believes have changed the Bank's categories. As an approved mortgage seller, the Bank is required to maintain a minimum level of capital specified by the United States Department of Housing and Urban Development. At September 30, 2019 and 2018, the Bank met these requirements. Capital amounts and ratios are presented in the following table: Actual Minimum Capital Requirement Ratio ¹ To Be Well Capitalized Amount Ratio Amount Ratio Amount Ratio (dollars in thousands) As of September 30, 2019 Tier 1 risk based capital (to risk-weighted assets): Consolidated $ 1,225,355 11.7 % $ 627,493 6.0 % N/A N/A Bank 1,201,476 11.5 % 627,311 6.0 % $ 836,415 8.0 % Total risk based capital (to risk-weighted assets): Consolidated 1,331,611 12.7 % 836,658 8.0 % N/A N/A Bank 1,272,733 12.2 % 836,415 8.0 % 1,045,519 10.0 % Tier 1 leverage capital (to average assets): Consolidated 1,225,355 10.1 % 483,487 4.0 % N/A N/A Bank 1,201,476 9.9 % 483,957 4.0 % 604,946 5.0 % Common Equity Tier 1 risk based capital (to risk-weighted assets): Consolidated 1,151,658 11.0 % 470,620 4.5 % N/A N/A Bank $ 1,201,476 11.5 % $ 470,483 4.5 % $ 679,587 6.5 % As of September 30, 2018 Tier 1 risk based capital (to risk-weighted assets): Consolidated $ 1,208,852 12.0 % $ 604,637 6.0 % N/A N/A Bank 1,168,110 11.6 % 604,467 6.0 % $ 805,957 8.0 % Total risk based capital (to risk-weighted assets): Consolidated 1,308,875 13.0 % 806,182 8.0 % N/A N/A Bank 1,233,133 12.2 % 805,957 8.0 % 1,007,446 10.0 % Tier 1 leverage capital (to average assets): Consolidated 1,208,852 10.7 % 451,939 4.0 % N/A N/A Bank 1,168,110 10.3 % 452,404 4.0 % 565,505 5.0 % Common Equity Tier 1 risk based capital (to risk-weighted assets): Consolidated 1,135,249 11.3 % 453,478 4.5 % N/A N/A Bank $ 1,168,110 11.6 % $ 453,351 4.5 % $ 654,840 6.5 % 1 Does not include capital conservation buffer of 2.5% and 1.875% at September 30, 2019 and 2018, respectively.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Financial Instruments with Off-Balance-Sheet Risk The Company is party to financial instruments with off-balance-sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments include commitments to extend credit and letters of credit. They involve, to varying degrees, elements of credit risk in excess of the amount recognized in the consolidated balance sheets. The Company’s exposure to credit loss in the event of nonperformance by the other party to the financial instrument for commitments to extend credit and letters of credit is represented by the contractual amount of those instruments. A summary of the Company’s commitments as of September 30, 2019 and 2018 is as follows. September 30, 2019 2018 (dollars in thousands) Commitments to extend credit $ 2,229,678 $ 2,344,550 Letters of credit 68,983 69,613 Commitments to extend credit are agreements to lend to a customer provided there is no violation of any condition established in the contract. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. Letters of credit are conditional commitments issued by the Company to guarantee the performance of a customer to a third party. Those guarantees are primarily issued to support public and private borrowing arrangements. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loans to customers. The Company evaluates each customer’s credit worthiness on a case-by-case basis. The credit and collateral policy for commitments and letters of credit is comparable to that for granting loans. Asset Sales The Bank regularly transfers financial assets as part of its mortgage banking activities. Transfers are recorded as sales when the criteria for surrender of control are met. The Bank has provided guarantees in connection with the sale of loans and has assumed a similar obligation in its acquisitions. The guarantees are generally in the form of asset buy back or make whole provisions that are triggered upon a credit event and remain in effect until the loans are collected. The maximum potential future payment related to these guarantees is not readily determinable because the Company’s obligation under these agreements depends on the occurrence of future events. There were $3.3 million of repurchased loans as of September 30, 2019 and 2018. Incurred losses related to these repurchased loans and guaranteed loans as of September 30, 2019, 2018 and 2017 are not significant. Financial Instruments with Concentration of Credit Risk by Geographic Location A substantial portion of the Company’s customers’ ability to honor their contracts is dependent on the economy in Nebraska, northern Missouri, northeastern Kansas, Iowa, southeastern Arizona, central Colorado, southeastern North Dakota, central Minnesota and South Dakota. Although the Company’s loan portfolio is diversified, there is a relationship in these regions between the agricultural economy and the economic performance of loans made to non-agricultural customers. The concentration of credit in the regional agricultural economy is taken into consideration by management in determining the allowance for loan and lease losses. Lease Commitments The Company leases several branch locations under terms of operating lease agreements expiring through March 31, 2034. The Company has the option to renew these leases for periods that range from 1 to 10 years. Total rent expense for these leases for each of the fiscal years ended September 30, 2019, 2018 and 2017, was $5.4 million. Approximate future minimum rental payments for operating leases in excess of one year in subsequent fiscal years are as follows. Fiscal year Amount (dollars in thousands) 2020 $ 5,327 2021 4,193 2022 3,486 2023 3,068 2024 2,563 2025 and thereafter 7,355 Total $ 25,992 Contingencies From time to time the Company is a party to various litigation matters and subject to various regulatory matters that arise in the ordinary course of business. The Company establishes reserves for such matters when potential losses become probable and can be reasonably estimated. The Company believes the ultimate resolution of existing litigation and regulatory matters will not have a material adverse effect on the financial condition, results of operations or cash flows. However, changes in circumstances or additional information could result in additional accruals or resolution of these matters in excess of established accruals, which could adversely affect the financial condition, results of operations or cash flows, potentially materially.

Transactions with Related Parti

Transactions with Related Parties	12 Months Ended
	Sep. 30, 2019
Related Party Transactions [Abstract]
Transactions with Related Parties	Transactions With Related Parties The Company has had, and may be expected to have in the future, banking transactions in the ordinary course of business with directors, executive officers, their immediate families, and affiliated companies in which they have 10% or more beneficial ownership (commonly referred to as related parties). Total loans committed to related parties were not significant at September 30, 2019 and 2018. There was no interest paid to related parties for each of the fiscal years ended September 30, 2019, 2018 and 2017. NAB provided the Company’s employees with restricted shares of NAB stock subsequent to meeting short- and long-term incentive goals. A payable was recorded between the Company and NAB based on the value and vesting schedule of issued shares. Final vesting of the shares occurred December 2017. The liability included in accrued expenses and other liabilities on the consolidated balance sheets was $0.0 million and $0.1 million at September 30, 2019 and 2018, respectively. The expense related to the restricted shares was negligible for each of the fiscal years ended September 30, 2019 and 2018 and $0.1 million for the fiscal year ended September 30, 2017, and was included within salaries and employee benefits on the consolidated statements of income.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Sep. 30, 2019
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 three levels of inputs that may be used to measure fair value are as follows: 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 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 September 30, 2019 and 2018. 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 September 30, 2019 and 2018. Fair Value Level 1 Level 2 Level 3 (dollars in thousands) 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 As of September 30, 2018 U.S. Treasury securities $ 167,172 $ 167,172 $ — $ — Mortgage-backed securities 1,149,707 — 1,149,707 — States and political subdivision securities 67,775 — 66,805 970 Other 996 — 996 — Total securities available for sale $ 1,385,650 $ 167,172 $ 1,217,508 $ 970 Derivatives-assets $ 1,911 $ — $ 1,911 $ — Derivatives-liabilities 2,632 — 2,632 — Fair value loans 865,386 — 865,386 — Loan servicing rights 3,087 — — 3,087 The following table presents the changes in Level 3 assets and liabilities measured at fair value on a recurring basis for the fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Other securities available for sale Balance, beginning of period $ 970 $ 1,069 $ 1,315 Additions 3,350 149 — Principal paydown (200) (248) (246) Balance, end of period $ 4,120 $ 970 $ 1,069 Loan servicing rights Balance, beginning of period $ 3,087 $ 4,074 $ 5,781 Realized and unrealized loss ¹ (832) (987) (1,707) Balance, end of period $ 2,255 $ 3,087 $ 4,074 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 tables present 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 September 30, 2019 and 2018. Fair Value Level 1 Level 2 Level 3 (dollars in thousands) As of September 30, 2019 Other repossessed property $ 34,721 $ — $ — $ 34,721 Impaired loans 413,644 — — 413,644 Loans held for sale, at lower of cost or fair value 7,351 — 7,351 — Property held for sale 2,757 — — 2,757 As of September 30, 2018 Other repossessed property $ 22,225 $ — $ — $ 22,225 Impaired loans 188,017 — — 188,017 Loans held for sale, at lower of cost or fair value 5,456 — 5,456 — Property held for sale 1,104 — — 1,104 The valuation techniques and significant unobservable inputs used to measure Level 3 fair value measurements at September 30, 2019 were as follows. Fair Value of Assets / (Liabilities) at September 30, 2019 Valuation Unobservable Range Weighted (dollars in thousands) Other repossessed property $ 34,721 Appraisal value Property specific adjustment N/A N/A Impaired loans 413,644 Appraisal value Property specific adjustment N/A N/A Property held for sale 2,757 Appraisal value Property specific adjustment N/A N/A Disclosures about Fair Value of Financial Instruments The following section summarizes the estimated fair value for financial instruments accounted for at amortized cost as of as of September 30, 2019 and September 30, 2018. Significant assets and liabilities that are not considered financial instruments 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 September 30, 2019 and September 30, 2018 are as follows. September 30, 2019 September 30, 2018 Level in Fair Value Hierarchy Carrying Amount Fair Carrying Amount Fair (dollars in thousands) Assets Cash and cash equivalents Level 1 $ 243,474 $ 243,474 $ 298,696 $ 298,696 Loans, net, excluding fair valued loans, loans held for sale and impaired loans ¹ Level 3 8,472,777 8,533,612 8,357,065 8,231,829 Liabilities Time deposits Level 2 $ 2,095,676 $ 2,101,239 $ 1,847,078 $ 1,848,550 FHLB advances and other borrowings Level 2 340,000 351,517 275,000 275,797 Securities sold under repurchase agreements Level 2 68,992 68,992 90,907 90,907 Subordinated debentures and subordinated notes payable Level 2 108,636 101,164 108,468 107,841 1 Includes $13.9 million and $13.0 million of net deferred loan fees at September 30, 2019 and 2018, respectively, of which carrying value approximates fair value.

Earnings per Share

Earnings per Share	12 Months Ended
	Sep. 30, 2019
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 for the fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands, except per share data) Net income $ 167,365 $ 157,916 $ 144,786 Weighted average common shares outstanding 57,154,865 58,938,169 58,770,708 Dilutive effect of stock based compensation 102,196 193,481 258,674 Weighted average common shares outstanding for diluted earnings per share calculation 57,257,061 59,131,650 59,029,382 Basic earnings per share $ 2.93 $ 2.68 $ 2.46 Diluted earnings per share $ 2.92 $ 2.67 $ 2.45 The Company had no shares of unvested performance stock as of September 30, 2019 and 2018 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 18,006 and no shares of anti-dilutive stock awards outstanding as of September 30, 2019 and 2018, respectively.

Parent Company Only Financial S

Parent Company Only Financial Statements	12 Months Ended
	Sep. 30, 2019
Condensed Financial Information Disclosure [Abstract]
Parent Company Only Financial Statements	Parent Company Only Financial Statements Parent company only financial information for Great Western Bancorp, Inc. is summarized as follows: Condensed Balance Sheets (Dollars in Thousands) September 30, 2019 2018 (dollars in thousands) Assets Cash and cash equivalents $ 57,543 $ 72,924 Investment in subsidiaries 1,950,077 1,873,422 Net deferred tax assets 1,716 1,489 Other assets 689 2,056 Total assets $ 2,010,025 $ 1,949,891 Liabilities and stockholders’ equity Subordinated debentures and subordinated notes payable $ 108,636 $ 108,468 Accrued expenses and other liabilities 1,140 872 Total liabilities 109,776 109,340 Stockholders’ equity Common stock 563 589 Additional paid-in capital 1,228,714 1,318,457 Retained earnings 657,475 553,014 Accumulated other comprehensive income (loss) 13,497 (31,509) Total stockholders’ equity 1,900,249 1,840,551 Total liabilities and stockholders’ equity $ 2,010,025 $ 1,949,891 Condensed Statements of Comprehensive Income (Dollars in Thousands) Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Income Dividends from subsidiary bank $ 148,128 $ 111,159 $ 62,470 Dividends on securities 19 51 123 Other 120 103 62 Total income 148,267 111,313 62,655 Expenses Interest on subordinated debentures and subordinated notes payable 5,540 5,040 4,464 Salaries and employee benefits 6,288 5,849 6,847 Professional fees 1,035 1,038 631 Other 2,653 2,456 2,204 Total expense 15,516 14,383 14,146 Income before income tax and equity in undistributed net income of subsidiaries 132,751 96,930 48,509 Income tax benefit (2,965) (3,075) (8,147) Income before equity in undistributed net income of subsidiaries 135,716 100,005 56,656 Equity in undistributed net income of subsidiaries 31,649 57,911 88,130 Net income $ 167,365 $ 157,916 $ 144,786 Condensed Statements of Cash Flows (Dollars in Thousands) Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Operating Activities Net income $ 167,365 $ 157,916 $ 144,786 Adjustments to reconcile net income to net cash provided by operating activities Depreciation and amortization 168 166 165 Gain on redemption of subordinated debentures — — (111) Stock-based compensation 4,582 4,419 6,810 Deferred income taxes (227) 13 (1,796) Changes in: Other assets 1,367 6,459 (823) Accrued interest and other liabilities 268 (140) 286 Equity in undistributed net income of subsidiaries (31,649) (57,911) (88,130) Net cash provided by operating activities 141,874 110,922 61,187 Financing Activities Redemption of subordinated debentures — — (3,625) Common stock repurchased (94,351) — (5,605) Dividends paid (62,904) (53,002) (43,474) Net cash used in financing activities (157,255) (53,002) (52,704) Net (decrease) increase in cash and cash equivalents (15,381) 57,920 8,483 Cash and cash equivalents, beginning of period 72,924 15,004 6,521 Cash and cash equivalents, end of period $ 57,543 $ 72,924 $ 15,004

Nature of Operations and Summ_2

Nature of Operations and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Segment Reporting	The "Segment Reporting" topic of the FASB ASC requires that public companies report certain information about operating segments. It also requires that public companies report certain information about their products and services, the geographic areas in which they operate, and their major customers. The Company is a holding company for a regional bank, which offers a wide array of products and services to its customers. Pursuant to its banking strategy, emphasis is placed on building relationships with its customers, as opposed to building specific lines of business. As a result, the Company is not organized and does not allocate resources around discernible lines of business or geographies and prefers to work as an integrated unit to customize solutions for its customers, with business line and geographic emphasis and product offerings changing over time as needs and demands change. Therefore, the Company only reports one segment, which is consistent with the Company’s preparation of financial information that is evaluated regularly by management in deciding how to allocate resources and assess performance.
Basis of Presentation	The accounting and reporting policies of the Company conform with U.S. GAAP, SEC rules and interpretive releases and prevailing practices within the banking industry. All significant income and expenses are recorded on the accrual basis. The accompanying consolidated financial statements include the accounts and results of the Company and its subsidiaries after elimination of all significant intercompany accounts and transactions.
Principles of Consolidation	The Company determines whether it has a controlling financial interest in an entity by first evaluating whether the entity is a voting interest entity or a variable interest entity under U.S. GAAP. Voting interest entities are entities in which the total equity investment at risk is sufficient to enable the entity to finance itself independently and provides the equity holders with the obligation to absorb losses, the right to receive residual returns and the right to make decisions about the entity’s activities. The Company consolidates voting interest entities in which it has all, or at least a majority of, the voting interest. As defined in applicable accounting standards, VIEs are entities that lack one or more of the characteristics of a voting interest entity. A controlling financial interest in a VIE is present when an enterprise has both the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and an obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. The enterprise with a controlling financial interest, known as the primary beneficiary, consolidates the VIE. The Company’s wholly-owned subsidiaries Great Western Statutory Trust IV, GWB Capital Trust VI, Sunstate Bancshares Trust II, HF Financial Capital Trust III, HF Financial Capital Trust IV, HF Financial Capital Trust V and HF Financial Capital Trust VI are VIEs for which the Company is not the primary beneficiary. Accordingly, the accounts of these trusts are not included on the Company’s consolidated financial statements. Certain previously reported amounts have been reclassified to conform to the current presentation.
Use of Estimates	U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported on the consolidated financial statements and accompanying notes. Actual results could differ from those estimates.
Subsequent Events	The Company evaluated subsequent events through the date its consolidated financial statements were issued. Other than those described above, there were no other material events or transactions that would require recognition on the consolidated financial statements or disclosure in the notes to the consolidated financial statements.
Business Combinations	The Company accounts for business combinations under the acquisition method of accounting in accordance with ASC Topic 805, Business Combinations ("ASC 805"). The Company recognizes the fair value of the assets acquired and liabilities assumed, immediately expenses transaction costs and accounts for restructuring plans separately from the business combination. There is no separate recognition of the acquired allowance for loan and lease losses on the acquirer’s balance sheet as credit related factors are incorporated directly into the fair value of the loans recorded at the acquisition date. The excess of the cost of the acquisition over the fair value of the net tangible and intangible assets acquired is recorded as goodwill. Alternatively, a bargain purchase gain is recorded equal to the amount by which the fair value of assets purchased exceeds the fair value of liabilities assumed and consideration paid. Results of operations of the acquired business are included on the consolidated statements of income from the effective date of acquisition. Fair values are subject to refinement for up to a year after the closing date of an acquisition as information relative to closing date fair values becomes available. Adjustments recorded to the acquired assets and liabilities are applied prospectively in accordance with ASU 2015-16.
Cash and Cash Equivalents	For purposes of the consolidated statements of cash flows, management has defined cash and cash equivalents to include cash on hand, amounts due from banks (including cash items in process of clearing), and amounts held at other financial institutions with an initial maturity of 90 days or less.
Securities	The Company classifies securities upon purchase in one of three categories: trading, held to maturity, or available for sale. Debt and equity securities held for resale are classified as trading. Debt securities for which the Company has the ability and positive intent to hold until maturity are classified as held to maturity. All other securities are classified as available for sale as they may be sold prior to maturity in response to changes in the Company’s interest rate risk profile, funding needs, demand for collateralized deposits by public entities or other reasons. Held to maturity securities are stated at amortized cost, which represents actual cost adjusted for premium amortization and discount accretion. Available for sale securities are stated at fair value, with unrealized gains and losses, net of related taxes, included in stockholders’ equity as a component of accumulated other comprehensive income (loss). Trading securities are stated at fair value. Realized and unrealized gains and losses from sales and fair value adjustments of trading securities are included in other noninterest income on the consolidated statements of income. Purchases and sales of securities are recognized on a trade date basis. The cost of securities sold is based on the specific identification method. Declines in the fair value of investment securities available for sale that are deemed to be other-than-temporary are recognized in earnings as a realized loss, and a new cost basis for the securities is established. In evaluating other-than-temporary impairment, management considers the length of time and extent to which the fair value has been less than amortized cost, the financial condition and near-term prospects of the issuer, and the intent and ability of the Company to retain its investment in the issuer for a period of time sufficient to allow for any anticipated recovery in fair value in the near term. Declines in the fair value of debt securities below amortized cost are deemed to be other-than-temporary in circumstances where: (1) the Company has the intent to sell a security; (2) it is more-likely-than-not that the Company will be required to sell the security before recovery of its amortized cost basis; or (3) the Company does not expect to recover the entire amortized cost basis of the security. If the Company intends to sell a security or if it is more-likely-than-not that the Company will be required to sell the security before recovery, an other-than-temporary impairment loss is recognized in earnings equal to the difference between the security’s amortized cost basis and its fair value. If the Company does not intend to sell the security or it is not more-likely-than-not that it will be required to sell the security before recovery, the other-than-temporary impairment write-down is separated into an amount representing credit loss, which is recognized in earnings, and an amount related to all other factors, which is recognized in other comprehensive income (loss). Interest and dividends, including amortization of premiums and accretion of discounts, are recognized as interest income when earned. Realized gains and losses on sales (using the specific identification method) and declines in value judged to be other-than-temporary are included in noninterest income on the consolidated statements of income.
Federal Home Loan Bank stock	Investments in the FHLB stock are restricted as to redemption and are carried at cost. Investments in FHLB stock are reviewed regularly for possible other-than-temporary impairment, and the cost basis of this investment is reduced by any declines in value determined to be other-than-temporary. FHLB stock is included in other assets on the consolidated balance sheets.
Loans	The Company’s accounting method for loans differs depending on whether the loans were originated or purchased and, for purchased loans, whether the loans were acquired at a discount related to evidence of credit deterioration since date of origination. Originated Loans Loans that management has the intent and ability to hold for the foreseeable future, or until maturity or pay-off, usually are reported at their outstanding principal balance, adjusted for charge-offs, the allowance for loan and lease losses, and any unamortized deferred fees or costs. Other fees not associated with originating a loan are recognized as fee income when earned. 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 Company has elected to measure certain long-term loans and written loan commitments at fair value to assist in managing interest rate risk for longer-term loans. Fair value loans are fixed-rate loans having original maturities of 5 years or greater (typically between 5 and 15 years) to our business and agri-business banking customers to assist them in facilitating their risk management strategies. The fair value option was elected upon the origination or acquisition of these loans and written loan commitments. Interest income is recognized in the same manner on loans reported at fair value as on non-fair value loans, except in regard to origination fees and costs which are recognized immediately upon closing. The changes in fair value of long-term loans and written loan commitments at fair value are reported in noninterest income. For loans held for sale, loan fees charged or received on origination, net of certain direct loan origination costs, are recognized in income when the related loan is sold. For loans held for investment, loan fees, net of certain direct loan origination costs, are deferred and the net amount is amortized as an adjustment of the related loan’s yield. The Company is generally amortizing these amounts over the contractual lives of the loans. Commitment fees are recognized as income when received. The Company makes commercial, agricultural, residential real estate, consumer and other loans to customers primarily in Arizona, Colorado, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota and South Dakota. The amount of collateral obtained, if deemed necessary, is based on management’s credit evaluation of the borrower. Collateral held varies but includes accounts receivable, marketable securities, inventory, equipment and real estate. Personal guarantees of the borrower or related parties and government guarantees are also obtained for some loans, which reduces the Company’s risk of loss. Loans originated and intended for sale in the secondary market are carried at the lower of cost or fair value. Loans held for sale include fixed rate single-family residential mortgage loans under contract to be sold in the secondary market. In most cases, loans are carried at cost and sold within 45 days. These loans are sold with the mortgage servicing rights released. Under limited circumstances, buyers may have recourse to return a purchased loan to the Company. Recourse conditions may include early payment default, breach of representation or warranties, or documentation deficiencies. Fair value of loans held for sale is determined based on prevailing market prices for loans with similar characteristics, sale contract prices, or, for certain portfolios, discounted cash flow analysis. Declines in fair value below cost (and subsequent recoveries) are recognized in net gain on sale of loans. Deferred fees and costs related to these loans are not amortized but are recognized as part of the cost basis of the loan at the time it is sold. Gains or losses on sales are recognized upon delivery and included in net gain on sale of loans. Purchased Loans Loans acquired (non-impaired and impaired) in a business acquisition are recorded at their fair value at the acquisition date. Credit discounts are included in the determination of fair value; therefore, an allowance for loan and lease losses is not recorded at the acquisition date. In determining the acquisition date fair value of purchased loans with evidence of credit deterioration ("purchased impaired loans"), and in subsequent accounting, the Company generally aggregates impaired purchased consumer and certain smaller balance impaired commercial loans into pools of loans with common risk characteristics, while accounting for larger-balance impaired commercial loans individually. Expected cash flows at the acquisition date in excess of the fair value of loans are recorded as interest income over the life of the loans using a level-yield method. Management estimates the cash flows expected to be collected at acquisition and at subsequent measurement dates using internal risk models, which incorporate the estimate of key assumptions, such as default rates, loss severity, and prepayment speeds. Subsequent to the acquisition date, decreases in cash flows over those expected at the acquisition date are recognized by recording an allowance for loan and lease losses. Subsequent increases in cash flow over those expected at the acquisition date are recognized as reductions to allowance for loan and lease losses to the extent impairment was previously recognized and thereafter as interest income prospectively. For purchased loans not deemed impaired at the acquisition date, the difference between the fair value and the unpaid principal balance of the loan at acquisition date is amortized or accreted to interest income using the effective interest method over the remaining period to contractual maturity. Credit Risk Management The Company’s strategy for credit risk management includes well-defined, centralized credit policies, uniform underwriting criteria and ongoing risk monitoring and review processes for all credit exposures. The strategy also emphasizes diversification on a geographic, industry, loan class type, and customer level; regular credit examinations; and management reviews of loans exhibiting deterioration of credit quality. The credit risk management strategy also includes a credit risk assessment process that performs assessments of compliance with commercial and consumer credit policies, risk ratings, and other critical credit information. Loan decisions are documented with respect to the borrower’s business, purpose of the loan, evaluation of the repayment sources, and the associated risks, evaluation of collateral, covenants and monitoring requirements, and risk rating rationale. The Company categorizes its loan portfolio into six classes, which is the level at which it develops and documents a systematic methodology to determine the allowance for loan and lease losses. The Company’s six loan portfolio classes are commercial real estate, agriculture, commercial non-real estate, residential real estate, consumer and other lending. The commercial real estate lending class includes loans made to small and middle market businesses, including multi-family properties. Loans in this class are generally secured by commercial real estate with cash flows generally being the primary source of repayment. Historical loss history and updated loan-to-value information on collateral-dependent loans are the primary factors in determining the allowance for loan and lease losses for the commercial real estate lending class. Key risk characteristics relevant to the commercial real estate lending class include the industry and geography of the borrower’s business, purpose of the loan, repayment sources, borrower’s debt capacity and financial performance, loan covenants, guarantees and nature of pledged collateral. The Company considers these risk characteristics in assigning risk ratings and estimating environmental factors considered in determining the allowance for loan and lease losses. The agriculture lending class includes loans made to agricultural individuals and businesses. Loans in this class are generally secured by operating assets and agriculture real estate and guaranteed by owners; cashflows are most often the primary source of repayment. Historical loss history and updated loan-to-value information on collateral-dependent loans are the primary factors in determining the allowance for loan and lease losses for the agriculture lending class. Key risk characteristics relevant to the agriculture lending class include the geography of the borrower’s operations, commodity prices and weather patterns, purpose of the loan, repayment sources, borrower’s debt capacity and financial performance, loan covenants, guarantees and nature of pledged collateral. The Company considers these risk characteristics in assigning risk ratings and estimating environmental factors considered in determining the allowance for loan and lease losses. The commercial non-real estate lending class includes loans made to small and middle market businesses, and loans made to public sector customers. Loans in this class are generally secured by business assets and guaranteed by owners; cashflows are most often a primary source of repayment. Historical loss history and updated loan-to-value information on collateral-dependent loans are the primary factors in determining the allowance for loan and lease losses for the commercial non-real estate lending class. Key risk characteristics relevant to the commercial non-real estate lending class include the industry and geography of the borrower’s business, purpose of the loan, repayment sources, borrower’s debt capacity and financial performance, loan covenants, guarantees and nature of pledged collateral. The Company considers these risk characteristics in assigning risk ratings and estimating environmental factors considered in determining the allowance for loan and lease losses. The residential real estate lending class includes loans made to consumer customers including residential mortgages, residential construction loans and home equity loans and lines. These loans are typically fixed rate loans secured by residential real estate. Home equity lines are revolving accounts giving the borrower the ability to draw and repay balances repeatedly, up to a maximum commitment, and are secured by residential real estate. Home equity lines typically have variable rate terms which are benchmarked to a prime rate. Historical loss history is the primary factor in determining the allowance for loan and lease losses for the residential real estate lending class. Key risk characteristics relevant to residential real estate lending class loans primarily relate to the borrower’s capacity and willingness to repay and include unemployment rates and other economic factors, and customer payment history. These risk characteristics, among others, are reflected in the environmental factors considered in determining the allowance for loan and lease losses. The consumer lending class includes loans made to consumer customers including loans secured by automobiles and other installment loans, and the other lending class includes credit card loans and unsecured revolving credit lines. Historical loss history is the primary factor in determining the allowance for loan and lease losses for the consumer and other lending classes. Key risk characteristics relevant to loans in the consumer and other lending classes primarily relate to the borrower’s capacity and willingness to repay and include unemployment rates and other economic factors, and customer payment and overall credit history. These risk characteristics, among others, are reflected in the environmental factors considered in determining the allowance for loan and lease losses. The other lending class includes all other loan relationships that do not fit within the categories above, primarily consumer and commercial credit cards, customer deposit account overdrafts, and lease receivables. 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 loan risk ratings are updated and monitored 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 consumer loans. Troubled Debt Restructurings Loans modified under troubled debt restructurings involve granting a concession to a borrower who is experiencing financial difficulty. These concessions could include a reduction in the interest rate on the loan, payment extensions, forgiveness of principal, forbearance, or other actions intended to maximize collection, which generally would not otherwise be considered. The Company's TDRs include performing and nonperforming TDRs, which consist of loans that continue to accrue interest at the loan's original interest rate when the Company expects to collect the remaining principal and interest on the loan, and nonaccrual TDRs, which include loans that are in a nonaccrual status and are no longer accruing interest, as the Company does not expect to collect the full amount of principal and interest owed from the borrower on these loans. At the time of modification (except for loans on nonaccrual status), a TDR is classified as nonperforming TDR until a six-month payment history of principal and interest payments, in accordance with the terms of the loan modification, is sustained, at which time the loan is moved to a performing status (performing TDR). If the Company does not expect to collect all principal and interest on the loan, the modified loan is classified as a nonaccrual TDR. All TDRs are accounted for as impaired loans and are included in the analysis of the allowance for loan and lease losses. A TDR that has been renewed for a borrower who is no longer experiencing financial difficulty and which yields a market rate of interest at the time of a renewal is no longer considered a TDR. Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments The Company maintains an allowance for loan and lease losses at a level believed to be appropriate to reserve for credit losses inherent in the loan portfolio. The allowance for loan and lease losses 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 and current economic conditions 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 and macroeconomic factors, such as changes in unemployment rates, gross domestic product, and consumer bankruptcy filings. All of these estimates are susceptible to significant change. 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. A loan is placed on nonaccrual status and accrual of interest is discontinued 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. 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 troubled debt restructurings. 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 Company maintains an ALLL for acquired impaired loans accounted for under ASC 310-30, resulting from decreases in expected cash flows arising from the periodic revaluation of these loans. Any decrease in expected cash flows in the individual loan pool is generally recognized in the current provision for loan and lease losses. Any increase in expected cash flows is generally not recognized immediately but is instead reflected as an adjustment to the related loan or pool's yield on a prospective basis once any previously recorded provision for loan and lease loss has been reversed. For acquired non-impaired loans accounted for under ASC 310-20, the Company utilizes methods to estimate the required allowance for loan and lease losses similar to originated loans; the required reserve is compared to the net carrying value of each acquired non-impaired loan (by class) to determine if a provision is required. Unfunded residential mortgage loan commitments entered into in connection with mortgage loans to be held for sale are considered derivatives and are recorded at fair value and included in other liabilities on the consolidated balance sheets with changes in fair value recorded in other interest income. All other unfunded loan commitments are generally related to providing credit facilities to customers and are not considered derivatives. For purchased loans, the fair value of the unfunded credit commitments is considered in determination of the fair value of the loans recorded at the date of acquisition. Reserves for credit exposure on all other unfunded credit commitments are recorded in other liabilities on the consolidated balance sheets. The Company maintains a reserve for unfunded commitments at a level believed to be sufficient to absorb estimated probable losses related to unfunded credit facilities.
FDIC Indemnification Asset and Clawback Liability	In conjunction with a FDIC assisted transaction of TierOne Bank in 2010, the Company entered into a loss share agreement with the FDIC covering certain single family residential mortgage loans with claim period ending June 2020. The agreement covers a portion of realized losses on loans, foreclosed real estate and certain other assets. The Company has recorded indemnification assets in other assets on the consolidated balance sheets representing estimated future amounts recoverable from the FDIC. Fair values of loans covered by the loss sharing agreement at the acquisition date were estimated based on projected cash flows available based on the expected probability of default, default timing and loss given default, the expected reimbursement rates (generally 80%) from the FDIC and other relevant terms of the loss sharing agreement. The initial fair value was established by discounting these expected cash flows with a market discount rate for instruments with like maturity and risk characteristics. The loss share assets are measured separately from the related loans and foreclosed real estate and recorded as an FDIC indemnification asset on the consolidated balance sheets because they are not contractually embedded in the loans and are not transferable with the loans should the Company choose to dispose of them. Subsequent to the acquisition date, reimbursements received from the FDIC for actual incurred losses reduce the carrying amount of the loss share assets. Reductions to expected losses on covered assets, to the extent such reductions to expected losses are the result of an improvement to the actual or expected cash flows from the covered assets, also reduce the carrying amount of the loss share assets. The rate of accretion of the indemnification asset discount included in interest income slows to mirror the accelerated accretion of the loan discount. Additional expected losses on covered assets, to the extent such expected losses result in the recognition of an allowance for loan and lease losses, increase the carrying amount of the loss share assets. A related increase in the value of the indemnification asset up to the amount covered by the FDIC is calculated based on the reimbursement rates from the FDIC and is included in other noninterest income. The corresponding loan accretion or amortization is recorded as a component of interest income on the consolidated statements of income. Although these assets are contractual receivables from the FDIC, there are no contractual interest rates. As part of the loss sharing agreement, the Company also assumed a liability ("FDIC Clawback Liability") to be paid within 45 days subsequent to the maturity or termination of the loss sharing agreement that is contingent upon actual losses incurred over the life of the agreement relative to expected losses considered in the consideration paid at acquisition date and the amount of losses reimbursed to the Company under the loss sharing agreement. The liability was recorded at fair value as of the acquisition date. The fair value was based on a discounted cash flow calculation that considered the formula defined in the loss sharing agreement and projected losses. The difference between the fair value at acquisition date and the projected losses is amortized through other noninterest expense. As projected losses and reimbursements are updated, as described above, the FDIC Clawback Liability is adjusted and a gain or loss is recorded in other noninterest expense.
Premises and Equipment	Premises and equipment are stated at cost less accumulated depreciation. Depreciation is computed principally by the straight-line method over the estimated useful lives of the assets. Costs incurred for maintenance and repairs are expensed as incurred. The range of estimated useful lives for buildings and building improvements are 10 to 40 years and 3 to 10 years for furniture and equipment.
Other Repossessed Property	Assets acquired through, or in lieu of, loan foreclosure are held for sale and are initially recorded at fair value less estimated cost to sell at the date of foreclosure, establishing a new cost basis. Subsequent to foreclosure, valuations are periodically performed by management, and the assets are carried at the lower of carrying amount or fair value less estimated cost to sell. Income and expenses from operations of repossessed property are included in noninterest expense.
Long-lived Asset Impairment	The Company evaluates the recoverability of the carrying value of long-lived assets whenever events or circumstances indicate the carrying amount may not be recoverable. If a long-lived asset is tested for recoverability and the undiscounted estimated future cash flows expected to result from the use and eventual disposition of the asset is less than the carrying amount of the asset, the asset’s carrying value is adjusted to fair value and an impairment loss is recognized as the amount by which the carrying amount of the long-lived asset exceeds its fair value.
Goodwill	Goodwill represents the excess purchase price over the fair value of identifiable net assets of acquired companies. In accordance with ASC Topic 350, Goodwill and Other Intangible Assets , 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 accordance with ASC 350-20, the Company can assess qualitative factors to determine whether it is more-likely-than-not the fair value of the reporting unit is less than its carrying amount. If the Company concludes based on the qualitative assessment that goodwill may be impaired, a quantitative one-step impairment test would then be applied. An impairment loss would be recognized for any excess of carrying value over fair value of the goodwill. Subsequent increases in goodwill would not be recognized on the consolidated financial statements.
Core Deposits and Other Intangibles	Intangible assets consist of core deposits, brand intangible, customer relationships, and other intangibles. Core deposits represent the identifiable intangible value assigned to core deposit bases arising from acquired companies. Brand intangible represents the value associated with the Bank charter. Customer relationships intangible represents the identifiable intangible value assigned to customer relationships arising from acquired companies. Other intangibles represent contractual franchise arrangements under which the franchiser grants the franchisee the right to perform certain functions within a designated geographical area. Core deposits and other intangibles are recorded in other assets on the consolidated balance sheets. The methods and lives used to amortize intangible assets are as follows. Intangible Method Years Core deposit Straight-line or effective yield 5 - 10 Brand intangible Straight-line 15 Customer relationships Straight-line 8.5 Other intangibles Straight-line 1.25 - 9.33
Bank Owned Life Insurance (BOLI)	BOLI represents life insurance policies on the lives of certain Company officers or former officers for which the Company is the beneficiary. The carrying amount of bank owned life insurance consists of the initial premium paid plus increases in cash value less the carrying amount associated with any death benefits received. Death benefits paid in excess of the applicable carrying amount are recognized as income, which is exempt from income taxes.
Loan Servicing Rights	The loan servicing rights asset recognized as part of the HF Financial acquisition was initially recorded at fair value. These servicing rights have subsequently been accounted for using the lower of cost or fair value method. Fair value is based on a valuation model that calculates the present value of estimated future net servicing income using key assumptions such as prepayment speeds and discount rate. The asset is amortized into mortgage banking income, net on the consolidated statements of income in proportion to and over the period of estimated net servicing income. Loan servicing rights are recorded in other assets on the consolidated balance sheets. Mortgage banking income and related fees are recognized when earned as the Company services mortgage loans for others. Mortgage banking income also includes gains and losses on sales of mortgage loans to other financial institutions or government agencies which are recognized as each sales transaction occurs.
Derivatives	The Company maintains an overall interest rate risk management strategy that permits the use of derivative instruments to modify exposure to interest rate risk. The Company enters into interest rate swap contracts to offset the interest rate risk associated with borrowers who lock in long-term fixed rates (greater than or equal to 5 years to maturity) through a fixed rate loan. Generally, under these swaps, the Company agrees with various swap counterparties to exchange the difference between fixed-rate and floating-rate interest amounts based upon notional principal amounts. These contracts do not qualify for hedge accounting. These interest rate derivative instruments are recognized as other assets or other liabilities on the consolidated balance sheets and measured at fair value, with changes in fair value reported in net realized and unrealized gain (loss) on derivatives on the consolidated statements of income. Since each fixed rate loan is paired with an offsetting derivative contract, the impact to net income is minimized. The Company also has back-to-back swaps with loan customers where the Company enters into an interest rate swap with loan customers to provide a facility to mitigate the interest rate risk associated with offering a fixed rate and simultaneously enters into a swap with an outside third party that is matched in exact offsetting terms. The back-to-back swaps are recorded at fair value and recognized as other assets or other liabilities, depending on the rights or obligations under the contract, on the consolidated balance sheet, with changes in fair value reported in net realized and unrealized gain (loss) on derivatives on the consolidated statements of income. In 2017 the Company began a new program of selling interest swaps directly to customers. These interest rate swaps sales are used to enable customers to achieve a long-term fixed rate by selling the customer a long-term variable rate loan indexed to LIBOR plus a credit spread whereby the Bank enters into an interest rate swap with our customer where the customer pays a fixed rate of interest set at the time of origination on the interest rate swap and then the customer receives a floating rate equal to the rate paid on the loan, thus resulting in a fixed rate of interest over the life of the interest rate swap. The bank minimizes the market and liquidity risks of the swaps entered into with the customer by entering into an offsetting position with a swap dealer. The Company enters into forward interest rate lock commitments on mortgage loans to be held for sale, which are commitments to originate loans whereby the interest rate on the loan is determined prior to funding. The Company also has corresponding forward sales contracts related to these interest rate lock commitments. Both the mortgage loan commitments and the related sales contracts are considered derivatives and are recorded at fair value and included in other assets or other liabilities on the consolidated balance sheets with changes in fair value offsetting each other in net realized and unrealized gain (loss) on derivatives on the consolidated statements of income.
Stock Based Compensation	Restricted and performance-based stock units/awards are classified as equity awards and accounted for under the treasury stock method. Compensation expense for non-vested stock units/awards is based on the fair value of the award on the measurement date, which, for the Company, is the date of the grant and is recognized ratably over the vesting or performance period of the award. The fair value of non-vested stock units/awards is generally the market price of the Company's stock on the date of grant. The Company accounts for forfeitures on an actual basis. In fiscal year 2017, the Company adopted ASU No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employees Share Based Payments Accounting. The Company's consolidated financial statements include a reclassification from additional paid-in capital to provision for income taxes of $0.3 million for the fiscal year ended September 30, 2017.
Income Taxes	Income tax expense includes two components: current and deferred. Current income tax expense reflects taxes to be paid or refunded for the current period by applying the provisions of the enacted tax law to the taxable income or excess of deductions over income. The Company determines deferred income taxes using the liability (or balance sheet) method. Under this method, the net deferred tax asset or liability is based on the tax effects of the differences between the book and tax basis of assets and liabilities, and enacted changes in tax rates and laws are recognized in the period in which they occur. Deferred income tax expense results from changes in deferred tax assets and liabilities between periods. Deferred tax assets are reduced by a valuation allowance if, based on the weight of evidence available, it is more-likely-than-not that some portion or all of a deferred tax asset will not be realized. Tax benefits related to uncertain tax positions are recognized if it is more-likely-than-not, based on the technical merits, that the tax position will be realized or sustained upon examination. The term "more-likely-than-not" means a likelihood of more than 50 percent; the terms "examined" and "upon examination" also include resolution of the related appeals or litigation processes, if any. A tax position that meets the more-likely-than-not recognition threshold is initially and subsequently measured as the largest amount of tax benefit that has a greater than 50 percent likelihood of being realized upon settlement with a taxing authority that has full knowledge of all relevant information. The determination of whether or not a tax position has met the more-likely-than-not recognition threshold considers the facts, circumstances, and information available at the reporting date and is subject to management’s judgment.
Transfers of Financial Assets	Transfers of financial assets are accounted for as sales when control over the assets has been surrendered. Control over transferred assets is deemed to be surrendered when (1) the assets have been isolated from the Company-put presumptively beyond reach of the Company and its creditors, even in bankruptcy or other receivership, (2) the transferee obtains the right (free of conditions that constrain it from taking advantage of that right) to pledge or exchange the transferred assets, and (3) the Company does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity or the ability to unilaterally cause the holder to return specific assets. Securities sold under agreements to repurchase are accounted for as collateralized financing transactions and are recorded at amounts at which the securities were financed, plus accrued interest.
Defined Benefit Plan	The Company assumed plan sponsorship of the HF Financial Corp. Pension Plan as part of the HF Financial acquisition. On October 25, 2017, the Board of Directors adopted a provision to terminate the Plan effective February 1, 2018. As of September 30, 2018, the transfer of all Pension Plan assets, liabilities and administrative responsibilities was completed.
Revenue Recognition	The Company adopted ASU 2014-09, " Revenue from Contracts with Customers (Topic 606) " and subsequent related ASUs effective October 1, 2018 using the modified retrospective approach, which establishes principles for reporting information about the nature, amount, timing and uncertainty of revenue and cash flows arising from the Company's contracts to provide goods or services to 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 discussed elsewhere within "Note 1. Nature of Operations and Summary of Significant Accounting Policies." 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.
Comprehensive Income	Comprehensive income consists of net income and other comprehensive income, net of applicable income taxes. For fiscal year 2019, other comprehensive income (loss) consisted of unrealized appreciation (depreciation) on available for sale securities. For fiscal years 2018 and 2017, other comprehensive income (loss) consisted of unrealized appreciation (depreciation) on available for sale securities and the defined benefit pension plan obligation acquired from HF Financial which covered former employees of HF Financial and its wholly-owned subsidiaries.
New Accounting Pronouncements	Accounting Standards Adopted in Fiscal Year 2019 In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting , which provided guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. Under ASU 2017-09, an entity will not apply modification accounting to a share-based payment award if all of the following are the same immediately before and after the change: (i) the award's fair value, (ii) the award's vesting conditions and (iii) the award's classification as an equity or liability instrument. The Company adopted the standard effective October 1, 2018 on a prospective basis. The adoption did not have a material impact on the consolidated financial statements. In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business , which contained amendments that clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. Under the existing implementation guidance in Topic 805, there are three elements of a business: inputs, processes, and outputs. While an integrated set of assets and activities (collectively referred to as a “set”) that is a business usually has outputs, outputs are not required to be present. In addition, all the inputs and processes that a seller uses in operating a set are not required if market participants can acquire the set and continue to produce outputs. ASU 2017-01 amendments provided a screen to determine when a set is not a business. If the screen is not met, the amendments (1) require that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output and (2) remove the evaluation of whether a market participant could replace missing elements. ASU 2017-01 provided a framework to assist entities in evaluating whether both an input and a substantive process are present. The Company adopted the standard effective October 1, 2018 on a prospective basis. The adoption did not have an impact on the consolidated financial statements. In October 2016, the FASB issued ASU 2016-17, Consolidation (Topic 810): Interests held through Related Parties that are under Common Control , which altered how a decision maker needs to consider indirect interests in a variable interest entity held through an entity under common control and simplified that analysis to require consideration of only an entity’s proportionate indirect interest in a VIE held through a common control party. The Company adopted the standard effective October 1, 2018. The adoption did not have an impact on the consolidated financial statements. In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Equity Transfers of Assets Other Than Inventory , which addressed improvement in accounting for income tax consequences of intra-equity transfers of assets other than inventory. This update required that an entity recognize the income tax consequences of the intra-equity transfer of an asset other than inventory when the transfer occurs. The update eliminated the exception for an intra-equity transfer for assets other than inventory. The Company adopted the standard effective October 1, 2018 using the modified retrospective transaction approach with no cumulative effect adjustments as a result of implementation. The adoption did not have an impact on the consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) , which addressed eight specific cash flow issues with the objective of reducing the existing diversity in presentations and classification in the statement of cash flows. The eight specific cash flow issues addressed include: debt prepayment or debt extinguishment costs; settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing; contingent consideration payments made after a business combination; proceeds from the settlement of insurance claims; proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; distributions received from equity method investees; beneficial interests in securitization transactions; and separately identifiable cash flows and application of the predominance principle. The Company adopted the standard effective October 1, 2018 using the retrospective transaction approach. The adoption did not have an impact on the consolidated financial statements. In January 2016, the FASB issued ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10) - Recognition and Measurement of Financial Assets and Financial Liabilities , which required equity investments, in general, to be measured at fair value with changes in fair value recognized in earnings. It also eliminated the requirement to disclose the methods and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost, required entities to use the "exit price" notion when measuring fair value, required an entity to present separately in other comprehensive income the portion of the total change in fair value of a liability resulting from a change in the measurement category and form on the balance sheet or accompanying notes, clarified that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available for sale securities in combination with the entity's other deferred tax assets, and simplified the impairment assessment of equity investments without readily determinable fair values. In February 2018, the FASB issued ASU 2018-03, Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10) , which clarified certain aspects of the guidance issued in ASU 2016-01. The Company adopted these standards effective October 1, 2018. Disclosure requirements were adopted on a prospective basis and there were no cumulative effect adjustments as a result of implementation. The adoption did not have a material impact on the consolidated financial statements. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) , which implemented a more robust framework that clarified the principles for recognizing revenue and gave greater consistency and comparability in revenue recognition practices. In the new framework, revenue is recognized in an amount that reflects the consideration to which the entity expects to be entitled in exchange for goods or services. The new model requirements include the identification of performance obligations in the contract with customers, a determination of the transaction price and an allocation of the price to those performance obligations. Revenue is recognized when performance obligations are satisfied. In 2015, the FASB issued ASU 2015-14, which deferred the effective date of ASU 2014-09 to annual reporting periods beginning after December 15, 2017. In 2016, the FASB issued ASU 2016-08, ASU 2016-10, ASU 2016-11, ASU 2016-12 and ASU 2016-20, all of which further clarified the implementation guidance, provided practical expedients and made technical corrections and improvements to Topic 606. The standard, along with subsequent guidance from FASB, listed several items that are specifically out of scope for ASU 2014-09, including but not limited to core interest income, derivative instruments, investments, and loan origination fees. The Company adopted this standard on October 1, 2018 using the modified retrospective method. In addition, the Company prospectively changed the presentation of direct expenses associated with credit and debit card interchange income, which are now netted against interchange income in service charges and other fees in noninterest income on the consolidated statements of income, previously included in data processing and communication expense, and brokerage charges, which are now netted against wealth management fees in noninterest income on the consolidated statements of income, previously included in professional fees. The net quantitative impact of these presentation changes decreased both revenue and expenses by $6.6 million for the fiscal year ended September 30, 2019; however, these presentation changes did not have an impact on net income. Prior period balances have not been restated to reflect these presentation changes. There were no significant cumulative effect adjustments as a result of implementation as the current revenue recognition policies generally conform with the principals in ASC Topic 606. For additional information, see "Note 1. Nature of Operations and Summary of Significant Accounting Policies." Accounting Standards Not Yet Adopted in Fiscal Year 2019 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 August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities , which amends 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 is to be applied to all existing hedging relationships on the date of adoption and will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted in any interim period, with the effect of adoption reflected as of the beginning of the fiscal year of adoption. The Company adopted this standard beginning October 1, 2019 with no 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. In November 2018 and April 2019, 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 , and ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments - Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments ). 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 the implementation plan and expects to complete the User Acceptance Testing phase of the third party vendor software during FQ1 2020. The Company does not expect to early adopt this standard and 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 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 disclosing key information about leasing arrangements. Lessees will be 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 allows lessors to exclude sales tax from consideration of the contract through a policy election and clarifies 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 on the consolidated balance sheets were $19.9 million and $20.9 million, respectively. The effect on retained earnings was immaterial.

Nature of Operations and Summ_3

Nature of Operations and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Schedule of amortization methods used and useful lives	The methods and lives used to amortize intangible assets are as follows. Intangible Method Years Core deposit Straight-line or effective yield 5 - 10 Brand intangible Straight-line 15 Customer relationships Straight-line 8.5 Other intangibles Straight-line 1.25 - 9.33
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. Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Noninterest income Service charges and other fees $ 43,893 $ 51,077 $ 55,725 Wealth management fees 8,914 9,219 9,118 Other 3,045 6,575 3,308 Noninterest income from contracts with customers within the scope of ASC Topic 606 ¹ 55,852 66,871 68,151 Noninterest income within the scope of other GAAP Topics ² 4,880 6,738 (4,937) Total noninterest income $ 60,732 $ 73,609 $ 63,214 1 Amounts for periods after October 1, 2018 are presented in accordance with ASC Topic 606, Revenue from Contracts with Customers, except for out of scope amounts. Amounts for periods prior to October 1, 2018 are presented in accordance with ASC Topic 605, Revenue Recognition, and have not been restated to conform with ASC Topic 606, Revenue from Contracts with Customers. 2 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.

Securities Available for Sale (

Securities Available for Sale (Tables)	12 Months Ended
	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Summary of amortized cost and approximate fair value of investments in securities	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 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 Amortized Gross Unrealized Gains Gross Unrealized Losses Estimated (dollars in thousands) As of September 30, 2018 U.S. Treasury securities $ 168,394 $ — $ (1,222) $ 167,172 Mortgage-backed securities: Government National Mortgage Association 442,458 35 (16,335) 426,158 Federal Home Loan Mortgage Corporation 297,380 — (7,055) 290,325 Federal National Mortgage Association 188,192 — (6,081) 182,111 Small Business Assistance Program 260,458 — (9,345) 251,113 States and political subdivision securities 69,566 4 (1,795) 67,775 Other 1,006 — (10) 996 Total $ 1,427,454 $ 39 $ (41,843) $ 1,385,650
Summary of amortized cost and approximate fair value of debt securities available for sale	The amortized cost and approximate fair value of debt securities available for sale as of September 30, 2019 and 2018, 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 any penalty. September 30, 2019 September 30, 2018 Amortized Estimated Amortized Estimated (dollars in thousands) Due in one year or less $ 58,377 $ 58,343 $ 111,842 $ 111,221 Due after one year through five years 89,836 90,601 114,920 113,069 Due after five years through ten years 12,110 12,324 11,076 10,535 Due after ten years — — 122 122 160,323 161,268 237,960 234,947 Mortgage-backed securities 1,603,955 1,620,903 1,188,488 1,149,707 Securities without contractual maturities 1,006 1,037 1,006 996 Total $ 1,765,284 $ 1,783,208 $ 1,427,454 $ 1,385,650
Summary of unrealized gains and 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 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) Less than 12 months 12 months or more Total Estimated Unrealized Estimated Unrealized Estimated Unrealized (dollars in thousands) As of September 30, 2018 U.S. Treasury securities $ 167,172 $ (1,222) $ — $ — $ 167,172 $ (1,222) Mortgage-backed securities 416,677 (8,427) 709,387 (30,389) 1,126,064 (38,816) States and political subdivision securities 23,534 (250) 42,282 (1,545) 65,816 (1,795) Other 996 (10) — — 996 (10) Total $ 608,379 $ (9,909) $ 751,669 $ (31,934) $ 1,360,048 $ (41,843)

Loans (Tables)

Loans (Tables)	12 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
Summary of net loans receivable	The following table presents the composition of net loans as of September 30, 2019 and 2018. September 30, 2019 2018 (dollars in thousands) Commercial real estate $ 5,092,410 $ 4,629,330 Agriculture 2,008,644 2,182,688 Commercial non-real estate 1,719,956 1,699,987 Residential real estate 812,208 837,569 Consumer 51,925 49,689 Other 47,541 46,487 Ending balance 9,732,684 9,445,750 Less: Unamortized discount on acquired loans (13,655) (18,283) Unearned net deferred fees and costs and loans in process (12,266) (11,543) Total $ 9,706,763 $ 9,415,924
Summary of the Company's nonaccrual loans	The following table presents the Company’s nonaccrual loans at September 30, 2019 and 2018, excluding ASC 310-30 loans. Loans greater than 90 days past due and still accruing interest as of September 30, 2019 and 2018 were $11.2 million and $0.2 million, respectively. September 30, 2019 2018 Nonaccrual loans (dollars in thousands) Commercial real estate $ 14,973 $ 22,871 Agriculture 77,880 107,198 Commercial non-real estate 9,502 6,887 Residential real estate 2,661 3,549 Consumer 74 61 Total $ 105,090 $ 140,566
Composition of loan portfolio by internal risk rating	The following table presents the composition of the loan portfolio by internally assigned grade as of September 30, 2019 and 2018. 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 $813.0 million for September 30, 2019 and $865.4 million for September 30, 2018. As of September 30, 2019 Commercial Real Estate Agriculture Commercial Residential Real Estate ¹ Consumer ¹ Other Total Credit Risk Profile by Internally Assigned Grade (dollars in thousands) 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. As of September 30, 2018 Commercial Real Estate Agriculture Commercial Residential Real Estate ¹ Consumer ¹ Other Total Credit Risk Profile by Internally Assigned Grade (dollars in thousands) Grade: Pass $ 4,108,314 $ 1,610,291 $ 1,401,418 $ 779,610 $ 48,979 $ 46,487 $ 7,995,099 Watchlist 53,150 239,392 19,503 4,548 322 — 316,915 Substandard 41,184 137,205 20,117 6,366 159 — 205,031 Doubtful 93 2 2,277 37 — — 2,409 Loss — — — — — — — Ending balance 4,202,741 1,986,890 1,443,315 790,561 49,460 46,487 8,519,454 Loans covered by a FDIC loss sharing agreement — — — 42,627 — — 42,627 Total $ 4,202,741 $ 1,986,890 $ 1,443,315 $ 833,188 $ 49,460 $ 46,487 $ 8,562,081 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.
Summary of past due financing receivables	The following table presents the Company’s past due loans at September 30, 2019 and 2018. 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 $813.0 million for September 30, 2019 and $865.4 million for September 30, 2018. 30-59 Days Past Due 60-89 Days Past Due 90 Days or Greater Past Due Total Current Total Financing Receivables As of September 30, 2019 (dollars in thousands) 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 30-59 Days Past Due 60-89 Days Past Due 90 Days or Greater Past Due Total Current Total Financing Receivables As of September 30, 2018 (dollars in thousands) Commercial real estate $ 920 $ 551 $ 9,135 $ 10,606 $ 4,192,135 $ 4,202,741 Agriculture 1,243 2,042 51,579 54,864 1,932,026 1,986,890 Commercial non-real estate 551 16 4,068 4,635 1,438,680 1,443,315 Residential real estate 913 200 1,747 2,860 787,701 790,561 Consumer 83 47 1 131 49,329 49,460 Other — — — — 46,487 46,487 Ending balance 3,710 2,856 66,530 73,096 8,446,358 8,519,454 Loans covered by a FDIC loss sharing agreement 30 233 471 734 41,893 42,627 Total $ 3,740 $ 3,089 $ 67,001 $ 73,830 $ 8,488,251 $ 8,562,081
Summary 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 $813.0 million for September 30, 2019 and $865.4 million for September 30, 2018. September 30, 2019 September 30, 2018 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance Related Allowance Impaired loans: (dollars in thousands) With an allowance recorded: Commercial real estate $ 26,003 $ 26,297 $ 4,159 $ 25,136 $ 25,223 $ 3,668 Agriculture 98,392 104,350 8,234 60,053 76,874 9,590 Commercial non-real estate 21,331 21,777 6,062 14,177 17,241 4,508 Residential real estate 3,829 4,311 1,795 4,509 5,153 2,210 Consumer 207 214 97 160 165 61 Total impaired loans with an allowance recorded 149,762 156,949 20,347 104,035 124,656 20,037 With no allowance recorded: Commercial real estate 28,272 66,631 — 15,764 58,141 — Agriculture 231,087 255,308 — 77,172 80,355 — Commercial non-real estate 21,579 31,414 — 8,905 18,047 — Residential real estate 3,290 5,454 — 2,177 4,574 — Consumer 1 108 — 1 118 — Total impaired loans with no allowance recorded 284,229 358,915 — 104,019 161,235 — Total impaired loans $ 433,991 $ 515,864 $ 20,347 $ 208,054 $ 285,891 $ 20,037 The following table presents the average recorded investment on impaired loans and interest income recognized on impaired loans for the fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Years Ended September 30, 2019 2018 2017 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 $ 42,374 $ 2,339 $ 54,434 $ 2,815 $ 42,347 $ 2,163 Agriculture 223,146 13,093 127,483 4,767 131,026 5,503 Commercial non-real estate 28,196 1,791 28,938 1,405 41,489 1,485 Residential real estate 6,889 410 7,156 452 8,900 453 Consumer 231 20 219 14 369 47 Total $ 300,836 $ 17,653 $ 218,230 $ 9,453 $ 224,131 $ 9,651
Summary of all non-accruing loans restructured in Troubled Debt Restructurings on financing receivables	The following table presents the recorded value of the Company’s TDR balances as of September 30, 2019 and 2018. September 30, 2019 September 30, 2018 Accruing Nonaccrual Accruing Nonaccrual (dollars in thousands) Commercial real estate $ 17,145 $ 904 $ 2,649 $ 2,616 Agriculture 22,929 24,762 13,248 73,741 Commercial non-real estate 4,398 4,257 3,420 656 Residential real estate 263 102 389 143 Consumer 107 48 77 — Total $ 44,842 $ 30,073 $ 19,783 $ 77,156 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 during the fiscal years ended September 30, 2019, 2018 and 2017. September 30, 2019 September 30, 2018 September 30, 2017 Recorded Investment Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Commercial real estate 2 $ 15,466 $ 15,466 1 $ 2,041 $ 2,041 2 $ 3,726 $ 3,726 Agriculture 16 11,537 11,537 5 10,753 10,753 13 18,902 18,902 Commercial non-real estate 2 1,445 1,445 — — — 9 2,044 2,044 Residential real estate — — — — — — 1 9 9 Consumer 2 188 188 1 73 73 1 8 8 Total accruing 22 $ 28,636 $ 28,636 7 $ 12,867 $ 12,867 26 $ 24,689 $ 24,689 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 during the fiscal years ended September 30, 2019, 2018 and 2017. September 30, 2019 September 30, 2018 September 30, 2017 Recorded Investment Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Commercial real estate 1 $ 882 $ 882 — $ — $ — — $ — $ — Agriculture 9 5,802 5,802 9 9,990 9,990 18 20,197 20,197 Commercial non-real estate 2 3,699 3,699 — — — 3 3,788 3,788 Residential real estate — — — — — — 2 133 133 Consumer — — — — — — 3 21 21 Total nonaccruing 12 $ 10,383 $ 10,383 9 $ 9,990 $ 9,990 26 $ 24,139 $ 24,139 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 fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Years Ended September 30, 2019 2018 2017 Number of Loans Recorded Investment Number of Loans Recorded Investment Number of Loans Recorded Investment (dollars in thousands) Commercial real estate — $ — — $ — — $ — Agriculture — — 1 366 2 8,383 Commercial non-real estate — — — — 1 — Residential real estate — — — — — — Consumer 1 — — — — — Total 1 $ — 1 $ 366 3 $ 8,383

Allowance for Loan and Lease _2

Allowance for Loan and Lease Losses (Tables)	12 Months Ended
	Sep. 30, 2019
Loans and Leases Receivable Disclosure [Abstract]
Allowance for credit losses on financing receivables	The following tables present the Company’s allowance for loan and lease losses roll forward for the fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Year Ended September 30, 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 (1,511) (24,847) (7,895) (998) (452) (1,358) (37,061) Recoveries 567 385 392 468 174 362 2,348 Provision 1,514 27,160 11,431 (56) 448 1,009 41,506 (Improvement) impairment of ASC 310-30 loans (520) — 29 (68) — — (559) Ending balance, September 30, 2019 $ 16,827 $ 30,819 $ 17,567 $ 4,095 $ 427 $ 1,039 $ 70,774 Fiscal Year Ended September 30, 2018 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Beginning balance, October 1, 2017 $ 16,941 $ 25,757 $ 14,114 $ 5,347 $ 329 $ 1,015 $ 63,503 Charge-offs (3,925) (9,473) (3,813) (569) (192) (1,932) (19,904) Recoveries 533 332 994 337 141 618 2,955 Provision 3,231 11,355 2,315 (451) (21) 1,325 17,754 (Improvement) impairment of ASC 310-30 loans (3) 150 — 85 — — 232 Ending balance, September 30, 2018 $ 16,777 $ 28,121 $ 13,610 $ 4,749 $ 257 $ 1,026 $ 64,540 Fiscal Year Ended September 30, 2017 Commercial Real Estate Agriculture Commercial Non-Real Estate Residential Real Estate Consumer Other Total (dollars in thousands) Beginning balance, October 1, 2016 $ 17,946 $ 25,115 $ 12,990 $ 7,106 $ 438 $ 1,047 $ 64,642 Charge-offs (2,043) (7,853) (12,576) (809) (196) (2,403) (25,880) Recoveries 485 415 652 507 102 1,041 3,202 Provision 643 7,965 13,048 (761) (15) 1,330 22,210 (Improvement) impairment of ASC 310-30 loans (90) 115 — (696) — — (671) Ending balance, September 30, 2017 $ 16,941 $ 25,757 $ 14,114 $ 5,347 $ 329 $ 1,015 $ 63,503 The following tables provide details regarding the allowance for loan and lease losses and balance by type of allowance as of September 30, 2019 and 2018. These tables are presented net of unamortized discount on acquired loans and excludes loans of $813.0 million measured at fair value, loans held for sale of $7.4 million, and guaranteed loans of $145.9 million for September 30, 2019; and loans measured at fair value of $865.4 million, loans held for sale of $5.5 million, and guaranteed loans of $160.3 million for September 30, 2018. 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 As of September 30, 2018 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 $ 3,668 $ 9,590 $ 4,508 $ 2,210 $ 61 $ — $ 20,037 Collectively evaluated for impairment 12,430 18,266 9,102 2,277 196 1,026 43,297 ASC 310-30 loans 679 265 — 262 — — 1,206 Total allowance $ 16,777 $ 28,121 $ 13,610 $ 4,749 $ 257 $ 1,026 $ 64,540 Financing Receivables Individually evaluated for impairment $ 40,900 $ 137,225 $ 23,082 $ 6,686 $ 161 $ — $ 208,054 Collectively evaluated for impairment 4,053,712 1,823,947 1,364,511 780,047 48,711 46,487 8,117,415 ASC 310-30 loans 27,001 2,815 416 40,025 588 — 70,845 Loans Outstanding $ 4,121,613 $ 1,963,987 $ 1,388,009 $ 826,758 $ 49,460 $ 46,487 $ 8,396,314

Accounting for Certain Loans _2

Accounting for Certain Loans Acquired with Deteriorated Credit Quality (Tables)	12 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
Troubled debt restructurings on financing receivables	The re-assessment of purchased credit impaired loans resulted in the following changes in the accretable yield during the fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Balance, beginning of period $ 34,973 $ 44,131 $ 38,124 Accretion (9,202) (13,193) (13,847) Reclassification from nonaccretable difference 276 4,035 19,854 Balance, end of period $ 26,047 $ 34,973 $ 44,131
Summary of impaired financing receivables	The following table provides purchased impaired loans at September 30, 2019 and 2018. September 30, 2019 September 30, 2018 Outstanding Balance ¹ Recorded Investment ² Carrying Value ³ Outstanding Balance ¹ Recorded Investment ² Carrying Value ³ (dollars in thousands) Commercial real estate $ 90,295 $ 22,124 $ 21,965 $ 100,761 $ 27,001 $ 26,322 Agriculture 4,462 2,756 2,491 4,841 2,815 2,551 Commercial non-real estate 7,190 221 192 7,475 416 416 Residential real estate 35,413 30,280 30,168 46,646 40,025 39,763 Consumer 493 438 438 656 588 588 Total lending $ 137,853 $ 55,819 $ 55,254 $ 160,379 $ 70,845 $ 69,640 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)	12 Months Ended
	Sep. 30, 2019
Banking and Thrift [Abstract]
Summary of activity related to the FDIC indemnification asset	The following table represents a summary of the activity related to the FDIC indemnification asset for the fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Balance, beginning of period $ 2,502 $ 5,704 $ 10,777 Amortization (1,386) (2,778) (4,748) Changes in expected reimbursements from FDIC for changes in expected credit losses (10) (122) (45) Changes in reimbursable expenses (41) (1,072) (986) Payments of covered losses to the FDIC 14 770 706 Balance, end of period $ 1,079 $ 2,502 $ 5,704

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Sep. 30, 2019
Property, Plant and Equipment [Abstract]
Summary of major classes of premises and equipment and the total amount of accumulated depreciation	The following table presents the major classes of premises and equipment and the total amount of accumulated depreciation as of September 30, 2019 and 2018. September 30, 2019 2018 (dollars in thousands) Land $ 31,107 $ 25,598 Buildings and building improvements 95,778 85,960 Furniture and equipment 26,688 27,490 Construction in progress 3,619 7,732 Total 157,192 146,780 Accumulated depreciation (36,547) (32,941) Premise and equipment, net $ 120,645 $ 113,839

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	12 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of derivative positions, notional amounts	The following table presents the notional amounts and gross fair values of all derivative assets and liabilities held by the Company as of September 30, 2019 and 2018. September 30, 2019 September 30, 2018 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 $ 1,259,765 $ 35 $ (38,755) $ 1,082,630 $ 22,696 $ (2,231) Customer counterparties 499,643 48,652 — 217,066 1,533 (2,160) Interest rate caps Financial institution counterparties 100 2 — — — — Customer counterparties 100 — (2) — — — Risk participation agreements 56,833 — (58) 37,351 — (444) Mortgage loan commitments 56,665 — (11) 22,195 — (28) Mortgage loan forward sale contracts 61,872 11 — 27,408 28 — Total $ 1,934,978 $ 48,700 $ (38,826) $ 1,386,650 $ 24,257 $ (4,863)
Summary of offsetting assets	The following tables provide information on the Company's netting adjustments as of September 30, 2019 and 2018. 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. Gross Fair Value Fair Value Offset Amount Cash Collateral Net Amount Presented on the Consolidated Balance Sheet (dollars in thousands) As of September 30, 2018 Total Derivative Assets $ 24,257 $ (2,231) $ (20,115) $ 1,911 Total Derivative Liabilities ¹ $ (4,863) $ 2,231 $ — $ (2,632) 1 There was an additional $6.2 million of collateral held for initial margin with a Futures Clearing Merchant for clearing derivatives at September 30, 2018 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 September 30, 2019 and 2018. 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. Gross Fair Value Fair Value Offset Amount Cash Collateral Net Amount Presented on the Consolidated Balance Sheet (dollars in thousands) As of September 30, 2018 Total Derivative Assets $ 24,257 $ (2,231) $ (20,115) $ 1,911 Total Derivative Liabilities ¹ $ (4,863) $ 2,231 $ — $ (2,632) 1 There was an additional $6.2 million of collateral held for initial margin with a Futures Clearing Merchant for clearing derivatives at September 30, 2018 and is included in other assets in the consolidated balance sheets.
Schedule of derivative instruments, effect on other comprehensive income	The effect of derivatives on the consolidated statements of income for the fiscal years ended September 30, 2019, 2018 and 2017 was as follows. Amount of (Loss) Gain Recognized in Consolidated Statements of Income Fiscal Years Ended September 30, Derivatives not designated as hedging instruments: Location of (Loss) Gain Recognized in Consolidated Statements of Income 2019 2018 2017 (dollars in thousands) Interest rate swaps and other derivatives Net realized and unrealized (loss) gain on derivatives $ (63,444) $ 44,596 $ 49,900 Mortgage loan commitments Net realized and unrealized (loss) gain on derivatives 17 (28) (48) Mortgage loan forward sale contracts Net realized and unrealized (loss) gain on derivatives (17) 28 48

Core Deposits and Other Intan_2

Core Deposits and Other Intangibles (Tables)	12 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of intangible assets subject to amortization	The following table presents a summary of intangible assets subject to amortization as of September 30, 2019 and 2018. Core Deposit Intangible Brand Other Total (dollars in thousands) 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 As of September 30, 2018 Gross carrying amount $ 7,339 $ 8,464 $ 538 $ 16,341 Accumulated amortization (2,610) (5,828) (191) (8,629) Net intangible assets $ 4,729 $ 2,636 $ 347 $ 7,712
Schedule of finite-lived intangible assets, future amortization expense	Estimated amortization expense of intangible assets in subsequent fiscal years is as follows. Fiscal year Amount (dollars in thousands) 2020 $ 1,430 2021 1,334 2022 1,249 2023 967 2024 498 2025 and thereafter 696 Total $ 6,174

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Sep. 30, 2019
Banking and Thrift [Abstract]
Summary of the composition of deposits	The following table presents the composition of deposits as of September 30, 2019 and 2018. September 30, 2019 2018 (dollars in thousands) Noninterest-bearing demand $ 1,956,025 $ 1,842,704 Interest-bearing demand 6,248,638 6,043,717 Time deposits, greater than $250,000 493,530 383,868 Time deposits, less than or equal to $250,000 1,602,146 1,463,210 Total $ 10,300,339 $ 9,733,499
Schedule of time deposit maturities	At September 30, 2019, the following table presents the scheduled maturities of time deposits in subsequent fiscal years. Accounts with no stated maturity date are included in 2020. Fiscal year Amount (dollars in thousands) 2020 $ 1,746,896 2021 250,248 2022 60,337 2023 26,858 2024 11,026 2025 and thereafter 311 Total $ 2,095,676

Securities Sold Under Agreeme_2

Securities Sold Under Agreements to Repurchase (Tables)	12 Months Ended
	Sep. 30, 2019
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Summary of repurchase agreements	The following tables present the gross obligation by the class of collateral pledged and the remaining contractual maturity of the agreements at September 30, 2019 and 2018. 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 September 30, 2018 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 $ 90,907 $ — $ — $ — $ 90,907 Total repurchase agreements $ 90,907 $ — $ — $ — $ 90,907

FHLB Advances and Other Borro_2

FHLB Advances and Other Borrowings (Tables)	12 Months Ended
	Sep. 30, 2019
Federal Home Loan Banks [Abstract]
Summary of FHLB advances and other borrowings	The following table presents the FHLB advances and other borrowings consist of the following at September 30, 2019 and 2018. September 30, 2019 2018 (dollars in thousands) Short-term borrowings: FHLB fed funds advance, interest rate of 2.09%, matured in October 2019 $ 15,000 $ 100,000 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 325,000 175,000 Total FHLB advances and other borrowings $ 340,000 $ 275,000
Summary of FHLB advances and other borrowings by maturity date	As of September 30, 2019, FHLB advances and other borrowings are due or callable (whichever is earlier) in subsequent fiscal years as follows. Fiscal year Amount (dollars in thousands) 2020 $ 15,000 2021 120,000 2022 60,000 2023 85,000 2024 60,000 2025 and thereafter — Total $ 340,000

Subordinated Debentures and S_2

Subordinated Debentures and Subordinated Notes Payable (Tables)	12 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Summary of subordinated debentures and subordinated notes payable	The following table presents the subordinated debentures and subordinated notes payable at September 30, 2019 and 2018. September 30, 2019 September 30, 2018 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 (2,223) (2,317) Total junior subordinated debentures payable, net of fair value adjustment 73,697 73,603 Subordinated notes payable Fixed to floating rate, 4.875% per annum 35,000 35,000 Less: unamortized debt issuance costs (61) (135) Total subordinated notes payable 34,939 34,865 Total subordinated debentures and subordinated notes payable $ 108,636 $ 108,468 1 Adjustment reflects the fair value adjustments related to the junior subordinated deferrable interest debentures assumed as part of the HF Financial acquisition.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Schedule of income tax expense (benefit) components	The provision for income taxes charged to operations consists of the following for the fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Currently paid or payable Federal $ 30,779 $ 42,261 $ 56,171 State 9,327 10,556 10,639 Total 40,106 52,817 66,810 Deferred tax expense Federal 7,507 20,205 2,477 State 617 1,097 154 Total 8,124 21,302 2,631 Total provision for income taxes $ 48,230 $ 74,119 $ 69,441
Schedule of effective income tax rate reconciliation	The income tax provision differs from the amount of income tax determined by applying a U.S. federal income tax rate of 21.0% for fiscal year 2019, a blended U.S. federal income tax rate of 24.5% for fiscal year 2018 and a U.S. federal income tax rate of 35.0% for fiscal year 2017 to pretax income due to the following. Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Income tax expense computed at the statutory rate $ 45,275 $ 56,915 $ 74,979 Increase (decrease) in income taxes resulting from: State income taxes, net of federal benefit 7,855 8,795 7,015 Tax exempt interest income (5,193) (5,778) (7,973) Tax benefit of stock-based compensation plans (91) (424) (2,153) Impact of enacted federal income tax rate reduction — 13,709 — Other 384 902 (2,427) Income tax expense, as reported $ 48,230 $ 74,119 $ 69,441
Schedule of deferred tax assets and liabilities	Net deferred tax assets (liabilities) consist of the following components at September 30, 2019 and 2018. September 30, 2019 2018 (dollars in thousands) Deferred tax assets: Allowance for loan and lease losses $ 17,214 $ 15,709 Compensation 4,017 2,577 Securities available for sale — 10,305 Other real estate owned 574 325 Core deposit intangible and other fair value adjustments 3,868 3,677 Excess tax basis of FDIC indemnification asset and clawback liability 4,095 3,633 Excess tax basis of loans acquired over carrying value 2,656 3,669 Other reserves 2,926 2,787 Other 6,350 5,711 Total deferred tax assets 41,700 48,393 Deferred tax liabilities: Goodwill and other intangibles (15,064) (11,567) Securities available for sale (4,419) — Premises and equipment (5,869) (6,248) Deferred REIT income (8,783) — Other (279) (446) Total deferred tax liabilities (34,414) (18,261) Net deferred tax assets $ 7,286 $ 30,132

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Summary of the Plans' 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 September 30, 2019 and 2018. The number of performance shares granted in the following table are reflected at the amount of achievement of the pre-established targets. September 30, 2019 September 30, 2018 September 30, 2017 Common Weighted-Average Grant Date Fair Value Common Weighted-Average Grant Date Fair Value Common Weighted-Average Grant Date Fair Value Restricted Shares Restricted shares, beginning of fiscal year 163,287 $ 37.86 180,337 $ 33.06 160,335 $ 26.89 Granted 106,753 37.27 89,376 41.07 90,363 39.35 Vested (76,210) 38.64 (97,682) 32.11 (68,293) 26.97 Forfeited (3,025) 38.67 (8,744) 35.99 (2,068) 30.91 Canceled — — — — — — Restricted shares, end of period 190,805 $ 37.20 163,287 $ 37.86 180,337 $ 33.06 Vested, but not issuable at end of period 50,770 $ 33.88 39,514 $ 32.90 29,287 $ 30.05 Performance Shares Performance shares, beginning of fiscal year 175,196 $ 36.29 133,604 $ 33.39 236,185 $ 20.28 Granted 60,583 32.77 53,682 29.52 137,612 39.43 Vested (59,937) 30.79 (7,017) 18.00 (235,055) 18.00 Forfeited (2,510) 39.25 (5,073) 37.75 (5,138) 19.80 Canceled — — — — — — Performance shares, end of period 173,332 $ 38.50 175,196 $ 36.29 133,604 $ 33.39 Vested, but not issuable at end of period 5,612 $ 18.00 5,612 $ 18.00 5,612 $ 18.00

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Sep. 30, 2019
Banking and Thrift [Abstract]
Schedule of regulatory capital amounts and requirements	Capital amounts and ratios are presented in the following table: Actual Minimum Capital Requirement Ratio ¹ To Be Well Capitalized Amount Ratio Amount Ratio Amount Ratio (dollars in thousands) As of September 30, 2019 Tier 1 risk based capital (to risk-weighted assets): Consolidated $ 1,225,355 11.7 % $ 627,493 6.0 % N/A N/A Bank 1,201,476 11.5 % 627,311 6.0 % $ 836,415 8.0 % Total risk based capital (to risk-weighted assets): Consolidated 1,331,611 12.7 % 836,658 8.0 % N/A N/A Bank 1,272,733 12.2 % 836,415 8.0 % 1,045,519 10.0 % Tier 1 leverage capital (to average assets): Consolidated 1,225,355 10.1 % 483,487 4.0 % N/A N/A Bank 1,201,476 9.9 % 483,957 4.0 % 604,946 5.0 % Common Equity Tier 1 risk based capital (to risk-weighted assets): Consolidated 1,151,658 11.0 % 470,620 4.5 % N/A N/A Bank $ 1,201,476 11.5 % $ 470,483 4.5 % $ 679,587 6.5 % As of September 30, 2018 Tier 1 risk based capital (to risk-weighted assets): Consolidated $ 1,208,852 12.0 % $ 604,637 6.0 % N/A N/A Bank 1,168,110 11.6 % 604,467 6.0 % $ 805,957 8.0 % Total risk based capital (to risk-weighted assets): Consolidated 1,308,875 13.0 % 806,182 8.0 % N/A N/A Bank 1,233,133 12.2 % 805,957 8.0 % 1,007,446 10.0 % Tier 1 leverage capital (to average assets): Consolidated 1,208,852 10.7 % 451,939 4.0 % N/A N/A Bank 1,168,110 10.3 % 452,404 4.0 % 565,505 5.0 % Common Equity Tier 1 risk based capital (to risk-weighted assets): Consolidated 1,135,249 11.3 % 453,478 4.5 % N/A N/A Bank $ 1,168,110 11.6 % $ 453,351 4.5 % $ 654,840 6.5 % 1 Does not include capital conservation buffer of 2.5% and 1.875% at September 30, 2019 and 2018, respectively.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Summary of the Company's commitments	A summary of the Company’s commitments as of September 30, 2019 and 2018 is as follows. September 30, 2019 2018 (dollars in thousands) Commitments to extend credit $ 2,229,678 $ 2,344,550 Letters of credit 68,983 69,613
Schedule of future minimum rental payments	Approximate future minimum rental payments for operating leases in excess of one year in subsequent fiscal years are as follows. Fiscal year Amount (dollars in thousands) 2020 $ 5,327 2021 4,193 2022 3,486 2023 3,068 2024 2,563 2025 and thereafter 7,355 Total $ 25,992

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Summary of the 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 September 30, 2019 and 2018. Fair Value Level 1 Level 2 Level 3 (dollars in thousands) 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 As of September 30, 2018 U.S. Treasury securities $ 167,172 $ 167,172 $ — $ — Mortgage-backed securities 1,149,707 — 1,149,707 — States and political subdivision securities 67,775 — 66,805 970 Other 996 — 996 — Total securities available for sale $ 1,385,650 $ 167,172 $ 1,217,508 $ 970 Derivatives-assets $ 1,911 $ — $ 1,911 $ — Derivatives-liabilities 2,632 — 2,632 — Fair value loans 865,386 — 865,386 — Loan servicing rights 3,087 — — 3,087
Summary of the 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 fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Other securities available for sale Balance, beginning of period $ 970 $ 1,069 $ 1,315 Additions 3,350 149 — Principal paydown (200) (248) (246) Balance, end of period $ 4,120 $ 970 $ 1,069 Loan servicing rights Balance, beginning of period $ 3,087 $ 4,074 $ 5,781 Realized and unrealized loss ¹ (832) (987) (1,707) Balance, end of period $ 2,255 $ 3,087 $ 4,074 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 the fair value measurement of assets and liabilities measured at fair value on a nonrecurring basis	The following tables present 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 September 30, 2019 and 2018. Fair Value Level 1 Level 2 Level 3 (dollars in thousands) As of September 30, 2019 Other repossessed property $ 34,721 $ — $ — $ 34,721 Impaired loans 413,644 — — 413,644 Loans held for sale, at lower of cost or fair value 7,351 — 7,351 — Property held for sale 2,757 — — 2,757 As of September 30, 2018 Other repossessed property $ 22,225 $ — $ — $ 22,225 Impaired loans 188,017 — — 188,017 Loans held for sale, at lower of cost or fair value 5,456 — 5,456 — Property held for sale 1,104 — — 1,104
Valuation techniques and significant observable inputs	The valuation techniques and significant unobservable inputs used to measure Level 3 fair value measurements at September 30, 2019 were as follows. Fair Value of Assets / (Liabilities) at September 30, 2019 Valuation Unobservable Range Weighted (dollars in thousands) Other repossessed property $ 34,721 Appraisal value Property specific adjustment N/A N/A Impaired loans 413,644 Appraisal value Property specific adjustment N/A N/A Property held for sale 2,757 Appraisal value Property specific adjustment N/A N/A
Summary of fair values for balance sheet instruments	Fair values for on-balance sheet instruments as of September 30, 2019 and September 30, 2018 are as follows. September 30, 2019 September 30, 2018 Level in Fair Value Hierarchy Carrying Amount Fair Carrying Amount Fair (dollars in thousands) Assets Cash and cash equivalents Level 1 $ 243,474 $ 243,474 $ 298,696 $ 298,696 Loans, net, excluding fair valued loans, loans held for sale and impaired loans ¹ Level 3 8,472,777 8,533,612 8,357,065 8,231,829 Liabilities Time deposits Level 2 $ 2,095,676 $ 2,101,239 $ 1,847,078 $ 1,848,550 FHLB advances and other borrowings Level 2 340,000 351,517 275,000 275,797 Securities sold under repurchase agreements Level 2 68,992 68,992 90,907 90,907 Subordinated debentures and subordinated notes payable Level 2 108,636 101,164 108,468 107,841 1 Includes $13.9 million and $13.0 million of net deferred loan fees at September 30, 2019 and 2018, respectively, of which carrying value approximates fair value.

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Sep. 30, 2019
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 for the fiscal years ended September 30, 2019, 2018 and 2017. Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands, except per share data) Net income $ 167,365 $ 157,916 $ 144,786 Weighted average common shares outstanding 57,154,865 58,938,169 58,770,708 Dilutive effect of stock based compensation 102,196 193,481 258,674 Weighted average common shares outstanding for diluted earnings per share calculation 57,257,061 59,131,650 59,029,382 Basic earnings per share $ 2.93 $ 2.68 $ 2.46 Diluted earnings per share $ 2.92 $ 2.67 $ 2.45

Parent Company Only Financial_2

Parent Company Only Financial Statements (Tables)	12 Months Ended
	Sep. 30, 2019
Condensed Financial Information Disclosure [Abstract]
Condensed Balance Sheet	Condensed Balance Sheets (Dollars in Thousands) September 30, 2019 2018 (dollars in thousands) Assets Cash and cash equivalents $ 57,543 $ 72,924 Investment in subsidiaries 1,950,077 1,873,422 Net deferred tax assets 1,716 1,489 Other assets 689 2,056 Total assets $ 2,010,025 $ 1,949,891 Liabilities and stockholders’ equity Subordinated debentures and subordinated notes payable $ 108,636 $ 108,468 Accrued expenses and other liabilities 1,140 872 Total liabilities 109,776 109,340 Stockholders’ equity Common stock 563 589 Additional paid-in capital 1,228,714 1,318,457 Retained earnings 657,475 553,014 Accumulated other comprehensive income (loss) 13,497 (31,509) Total stockholders’ equity 1,900,249 1,840,551 Total liabilities and stockholders’ equity $ 2,010,025 $ 1,949,891
Condensed Statements of Comprehensive Income	Condensed Statements of Comprehensive Income (Dollars in Thousands) Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Income Dividends from subsidiary bank $ 148,128 $ 111,159 $ 62,470 Dividends on securities 19 51 123 Other 120 103 62 Total income 148,267 111,313 62,655 Expenses Interest on subordinated debentures and subordinated notes payable 5,540 5,040 4,464 Salaries and employee benefits 6,288 5,849 6,847 Professional fees 1,035 1,038 631 Other 2,653 2,456 2,204 Total expense 15,516 14,383 14,146 Income before income tax and equity in undistributed net income of subsidiaries 132,751 96,930 48,509 Income tax benefit (2,965) (3,075) (8,147) Income before equity in undistributed net income of subsidiaries 135,716 100,005 56,656 Equity in undistributed net income of subsidiaries 31,649 57,911 88,130 Net income $ 167,365 $ 157,916 $ 144,786
Condensed Statements of Cash Flows	Condensed Statements of Cash Flows (Dollars in Thousands) Fiscal Years Ended September 30, 2019 2018 2017 (dollars in thousands) Operating Activities Net income $ 167,365 $ 157,916 $ 144,786 Adjustments to reconcile net income to net cash provided by operating activities Depreciation and amortization 168 166 165 Gain on redemption of subordinated debentures — — (111) Stock-based compensation 4,582 4,419 6,810 Deferred income taxes (227) 13 (1,796) Changes in: Other assets 1,367 6,459 (823) Accrued interest and other liabilities 268 (140) 286 Equity in undistributed net income of subsidiaries (31,649) (57,911) (88,130) Net cash provided by operating activities 141,874 110,922 61,187 Financing Activities Redemption of subordinated debentures — — (3,625) Common stock repurchased (94,351) — (5,605) Dividends paid (62,904) (53,002) (43,474) Net cash used in financing activities (157,255) (53,002) (52,704) Net (decrease) increase in cash and cash equivalents (15,381) 57,920 8,483 Cash and cash equivalents, beginning of period 72,924 15,004 6,521 Cash and cash equivalents, end of period $ 57,543 $ 72,924 $ 15,004

Nature of Operations and Summ_4

Nature of Operations and Summary of Significant Accounting Policies - Narrative (Details)		Oct. 24, 2019$ / shares	Oct. 01, 2019USD ($)	Mar. 31, 2018USD ($)	Sep. 30, 2019USD ($)segmentportfolio_classreporting_unit$ / shares	Sep. 30, 2018USD ($)$ / shares		Sep. 30, 2017USD ($)$ / shares
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of reportable segments | segment					1
Dividends per share (in dollars per share) | $ / shares					$ 1.10	$ 0.90		$ 0.74
Maturity period of loans and loan commitments					5 years
Number of loan portfolio classes | portfolio_class					6
FDIC Indemnification, expected reimbursement rate (as a percent)					80.00%
FDIC, Clawback Liability, payment period following termination or maturity of agreement					45 days
Residential real estate loans in process of foreclosure					$ 600,000	$ 1,100,000
Impairment of long-lived assets					$ 0	0		$ 0
Number of reporting units | reporting_unit					1
Impairment of goodwill					$ 0	0		0
Impairment of intangible assets					0	0		0
Provision for income taxes					$ 48,230,000	74,119,000		69,441,000
Reclassification from AOCI to retained earnings	[1]					0
Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Dividends per share (in dollars per share) | $ / shares		$ 0.30
Subsequent Event | Independent Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount of loans under management			$ 306,000,000
Consideration transferred			$ 4,700,000
Accumulated Other Comprehensive Income (Loss)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Reclassification from AOCI to retained earnings				$ 2,400,000		$ (2,353,000)	[1]
Adjustments for New Accounting Principle, Early Adoption | Accounting Standards Update 2016-09
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for income taxes								$ 300,000
Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maturity period of loans and loan commitments					5 years
Minimum | Buildings and building improvements
Accounts, Notes, Loans and Financing Receivable [Line Items]
Premises and equipment, useful life					10 years
Minimum | Furniture and equipment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Premises and equipment, useful life					3 years
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maturity period of loans and loan commitments					15 years
Maximum | Buildings and building improvements
Accounts, Notes, Loans and Financing Receivable [Line Items]
Premises and equipment, useful life					40 years
Maximum | Furniture and equipment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Premises and equipment, useful life					10 years
[1]	Reclassification due to adoption of ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income .

Nature of Operations and Summ_5

Nature of Operations and Summary of Significant Accounting Policies - Amortization Method and Estimated Lives of Intangible Assets (Details)	12 Months Ended
	Sep. 30, 2019
Core deposit | Minimum
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life	5 years
Core deposit | Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life	10 years
Brand intangible
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life	15 years
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life	8 years 6 months
Other intangibles | Minimum
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life	1 year 3 months
Other intangibles | Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life	9 years 3 months 29 days

Nature of Operations ans Summar

Nature of Operations ans Summary of Significant Policies - Disaggregation of Noninterest Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 55,852	$ 66,871	$ 68,151
Noninterest income within the scope of other GAAP Topics	4,880	6,738	(4,937)
Total noninterest income	60,732	73,609	63,214
Service charges and other fees
Disaggregation of Revenue [Line Items]
Revenue	43,893	51,077	55,725
Wealth management fees
Disaggregation of Revenue [Line Items]
Revenue	8,914	9,219	9,118
Other
Disaggregation of Revenue [Line Items]
Revenue	$ 3,045	$ 6,575	$ 3,308

New Accounting Standards (Detai

New Accounting Standards (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Oct. 01, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Noninterest income from contracts with customers within the scope of ASC Topic 606	$ 55,852	$ 66,871	$ 68,151
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Noninterest income from contracts with customers within the scope of ASC Topic 606	$ 6,600
Accounting Standards Update 2016-02 | Subsequent Event
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Right-of-use asset				$ 19,900
Lease liability				$ 20,900

Restrictions on Cash and Cash_2

Restrictions on Cash and Cash Equivalents - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
Cash and Cash Equivalents [Abstract]
Reserve balances	$ 51.2	$ 53.7

Securities Available for Sale -

Securities Available for Sale - Amortized Cost and Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	$ 1,765,284	$ 1,427,454
Gross Unrealized Gains	22,421	39
Gross Unrealized Losses	(4,497)	(41,843)
Estimated Fair Value	1,783,208	1,385,650
U.S. Treasury securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	94,178	168,394
Gross Unrealized Gains	599	0
Gross Unrealized Losses	(32)	(1,222)
Estimated Fair Value	94,745	167,172
Mortgage backed-securities | Government National Mortgage Association
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	501,139	442,458
Gross Unrealized Gains	3,374	35
Gross Unrealized Losses	(3,027)	(16,335)
Estimated Fair Value	501,486	426,158
Mortgage backed-securities | Federal Home Loan Mortgage Corporation
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	463,974	297,380
Gross Unrealized Gains	8,840	0
Gross Unrealized Losses	(770)	(7,055)
Estimated Fair Value	472,044	290,325
Mortgage backed-securities | Federal National Mortgage Association
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	322,340	188,192
Gross Unrealized Gains	5,409	0
Gross Unrealized Losses	(398)	(6,081)
Estimated Fair Value	327,351	182,111
Mortgage backed-securities | Small Business Assistance Program
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	316,502	260,458
Gross Unrealized Gains	3,674	0
Gross Unrealized Losses	(154)	(9,345)
Estimated Fair Value	320,022	251,113
States and political subdivision securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	66,145	69,566
Gross Unrealized Gains	494	4
Gross Unrealized Losses	(116)	(1,795)
Estimated Fair Value	66,523	67,775
Other
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	1,006	1,006
Gross Unrealized Gains	31	0
Gross Unrealized Losses	0	(10)
Estimated Fair Value	$ 1,037	$ 996

Securities Available for Sale_2

Securities Available for Sale - Schedule of Available For Sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Amortized  Cost
Due in one year or less	$ 58,377	$ 111,842
Due after one year through five years	89,836	114,920
Due after five years through ten years	12,110	11,076
Due after ten years	0	122
Amortized  Cost	160,323	237,960
Estimated Fair Value
Due in one year or less	58,343	111,221
Due after one year through five years	90,601	113,069
Due after five years through ten years	12,324	10,535
Due after ten years	0	122
Estimated Fair Value	161,268	234,947
Amortized  Cost	1,765,284	1,427,454
Estimated Fair Value	1,783,208	1,385,650
Securities without contractual maturities, Amortized Cost	1,006	1,006
Securities without contractual maturities, Fair Value	1,037	996
Mortgage-backed securities
Estimated Fair Value
Amortized  Cost	1,603,955	1,188,488
Estimated Fair Value	$ 1,620,903	$ 1,149,707

Securities Available for Sale_3

Securities Available for Sale - Narrative (Details)	12 Months Ended
	Sep. 30, 2019USD ($)security	Sep. 30, 2018USD ($)security	Sep. 30, 2017USD ($)
Investments, Debt and Equity Securities [Abstract]
Proceeds from sale of AFS securities	$ 175,007,000	$ 24,971,000	$ 5,074,000
Gross gains (pre-tax)	300,000	0	100,000
Gross losses (pre-tax)	500,000	0	0
Other-than-temporary impairment losses recognized in earnings	0	0	$ 0
Securities pledged as collateral	$ 863,900,000	$ 787,400,000
Percentage of investment portfolio in continuous loss position (as a percent)	36.00%	98.00%
Number of securities in an unrealized loss position (number of securities) | security	169	390

Securities Available for Sale_4

Securities Available for Sale - Schedule of Gross Unrealized Losses on Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Estimated Fair Value
Less than 12 months	$ 94,612	$ 608,379
12 months or more	543,401	751,669
Estimated Fair Value	638,013	1,360,048
Unrealized Losses
Less than 12 months	(205)	(9,909)
12 months or more	(4,292)	(31,934)
Unrealized Losses	(4,497)	(41,843)
U.S. Treasury securities
Estimated Fair Value
Less than 12 months	0	167,172
12 months or more	44,729	0
Estimated Fair Value	44,729	167,172
Unrealized Losses
Less than 12 months	0	(1,222)
12 months or more	(32)	0
Unrealized Losses	(32)	(1,222)
Mortgage-backed securities
Estimated Fair Value
Less than 12 months	94,612	416,677
12 months or more	474,979	709,387
Estimated Fair Value	569,591	1,126,064
Unrealized Losses
Less than 12 months	(205)	(8,427)
12 months or more	(4,144)	(30,389)
Unrealized Losses	(4,349)	(38,816)
States and political subdivision securities
Estimated Fair Value
Less than 12 months	0	23,534
12 months or more	23,693	42,282
Estimated Fair Value	23,693	65,816
Unrealized Losses
Less than 12 months	0	(250)
12 months or more	(116)	(1,545)
Unrealized Losses	(116)	(1,795)
Other
Estimated Fair Value
Less than 12 months	0	996
12 months or more	0	0
Estimated Fair Value	0	996
Unrealized Losses
Less than 12 months	0	(10)
12 months or more	0	0
Unrealized Losses	$ 0	$ (10)

Loans - Schedule of Financing R

Loans - Schedule of Financing Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	$ 9,732,684	$ 9,445,750
Less:
Less: Unamortized discount on acquired loans	(13,655)	(18,283)
Unearned net deferred fees and costs and loans in process	(12,266)	(11,543)
Total	9,706,763	9,415,924
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	5,092,410	4,629,330
Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	2,008,644	2,182,688
Commercial non-real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	1,719,956	1,699,987
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	812,208	837,569
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	51,925	49,689
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	$ 47,541	$ 46,487

Loans - Narrative (Details)

Loans - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans covered by FDIC loss share agreement	$ 31,891	$ 42,627
Loan held for sale	7,351	5,456
Loans and written loan commitments at fair value under the fair value option	812,991	865,386
Unamortized discount on acquired loans	13,900	13,000
Loans in process	(1,600)	(1,500)
Guaranteed loans	8,752,832	8,396,314
Principal balances of residential real estate loans sold	288,100	266,500
Loans greater than 90 days past due and still accruing interest	11,200	200
Valuation adjustments made to repossessed properties	2,300	1,600
Specific reserves included in the allowance for loan losses for TDRs	10,300	9,200
Troubled debt restructuring, commitments to lend additional funds to borrowers	200	300
Transfers out of troubled debt restructuring status	0	800	$ 5,500
Loans Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and written loan commitments at fair value under the fair value option	813,000	865,400
Loans Guaranteed by US Government Authorities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Guaranteed loans	$ 154,200	$ 168,600

Loans - Summary of Nonaccrual L

Loans - Summary of Nonaccrual Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans	$ 105,090	$ 140,566
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans	14,973	22,871
Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans	77,880	107,198
Commercial non-real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans	9,502	6,887
Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans	2,661	3,549
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans	$ 74	$ 61

Loans - Composition of the Loan

Loans - Composition of the Loan Portfolio by Internal Risk Rating (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	$ 8,874,149	$ 8,519,454
Loans covered by FDIC loss share agreement	31,891	42,627
Total	8,906,040	8,562,081
Pass
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	8,066,457	7,995,099
Watchlist
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	375,787	316,915
Substandard
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	425,685	205,031
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	6,220	2,409
Loss
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	0	0
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	4,573,084	4,202,741
Loans covered by FDIC loss share agreement	0	0
Total	4,573,084	4,202,741
Commercial real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	4,433,530	4,108,314
Commercial real estate | Watchlist
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	85,256	53,150
Commercial real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	54,242	41,184
Commercial real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	56	93
Commercial real estate | Loss
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	0	0
Agriculture
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	1,854,539	1,986,890
Loans covered by FDIC loss share agreement	0	0
Total	1,854,539	1,986,890
Agriculture | Pass
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	1,346,436	1,610,291
Agriculture | Watchlist
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	179,965	239,392
Agriculture | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	322,327	137,205
Agriculture | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	5,811	2
Agriculture | Loss
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	0	0
Commercial non-real estate
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	1,570,215	1,443,315
Loans covered by FDIC loss share agreement	0	0
Total	1,570,215	1,443,315
Commercial non-real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	1,424,357	1,401,418
Commercial non-real estate | Watchlist
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	103,514	19,503
Commercial non-real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	42,048	20,117
Commercial non-real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	296	2,277
Commercial non-real estate | Loss
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	0	0
Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	777,012	790,561
Loans covered by FDIC loss share agreement	31,891	42,627
Total	808,903	833,188
Residential real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	763,797	779,610
Residential real estate | Watchlist
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	6,297	4,548
Residential real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	6,863	6,366
Residential real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	55	37
Residential real estate | Loss
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	0	0
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	51,758	49,460
Loans covered by FDIC loss share agreement	0	0
Total	51,758	49,460
Consumer | Pass
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	50,796	48,979
Consumer | Watchlist
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	755	322
Consumer | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	205	159
Consumer | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	2	0
Consumer | Loss
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	0	0
Other
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	47,541	46,487
Loans covered by FDIC loss share agreement	0	0
Total	47,541	46,487
Other | Pass
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	47,541	46,487
Other | Watchlist
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	0	0
Other | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	0	0
Other | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	0	0
Other | Loss
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	$ 0	$ 0

Loans - Past Due Loans (Details

Loans - Past Due Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	$ 8,874,149	$ 8,519,454
Loans covered by FDIC loss share agreement	31,891	42,627
Total	8,906,040	8,562,081
Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	64,979	73,096
Loans covered by FDIC loss share agreement	1,277	734
Total	66,256	73,830
Past Due | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	21,302	3,710
Loans covered by FDIC loss share agreement	536	30
Total	21,838	3,740
Past Due | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	2,743	2,856
Loans covered by FDIC loss share agreement	410	233
Total	3,153	3,089
Past Due | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	40,934	66,530
Loans covered by FDIC loss share agreement	331	471
Total	41,265	67,001
Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	8,809,170	8,446,358
Loans covered by FDIC loss share agreement	30,614	41,893
Total	8,839,784	8,488,251
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	4,573,084	4,202,741
Loans covered by FDIC loss share agreement	0	0
Total	4,573,084	4,202,741
Commercial real estate | Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	6,632	10,606
Commercial real estate | Past Due | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	3,587	920
Commercial real estate | Past Due | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	570	551
Commercial real estate | Past Due | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	2,475	9,135
Commercial real estate | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	4,566,452	4,192,135
Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,854,539	1,986,890
Loans covered by FDIC loss share agreement	0	0
Total	1,854,539	1,986,890
Agriculture | Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	47,767	54,864
Agriculture | Past Due | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	13,411	1,243
Agriculture | Past Due | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,267	2,042
Agriculture | Past Due | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	33,089	51,579
Agriculture | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,806,772	1,932,026
Commercial non-real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,570,215	1,443,315
Loans covered by FDIC loss share agreement	0	0
Total	1,570,215	1,443,315
Commercial non-real estate | Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	8,476	4,635
Commercial non-real estate | Past Due | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	3,932	551
Commercial non-real estate | Past Due | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	120	16
Commercial non-real estate | Past Due | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	4,424	4,068
Commercial non-real estate | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,561,739	1,438,680
Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	777,012	790,561
Loans covered by FDIC loss share agreement	31,891	42,627
Total	808,903	833,188
Residential real estate | Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,926	2,860
Residential real estate | Past Due | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	311	913
Residential real estate | Past Due | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	676	200
Residential real estate | Past Due | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	939	1,747
Residential real estate | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	775,086	787,701
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	51,758	49,460
Loans covered by FDIC loss share agreement	0	0
Total	51,758	49,460
Consumer | Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	178	131
Consumer | Past Due | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	61	83
Consumer | Past Due | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	110	47
Consumer | Past Due | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	7	1
Consumer | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	51,580	49,329
Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	47,541	46,487
Loans covered by FDIC loss share agreement	0	0
Total	47,541	46,487
Other | Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	0	0
Other | Past Due | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	0	0
Other | Past Due | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	0	0
Other | Past Due | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	0	0
Other | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	$ 47,541	$ 46,487

Loans - Impaired Financing Rece

Loans - Impaired Financing Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
With an allowance recorded:
Recorded Investment	$ 149,762	$ 104,035
Unpaid Principal Balance	156,949	124,656
Related Allowance	20,347	20,037
With no allowance recorded:
Recorded Investment	284,229	104,019
Unpaid Principal Balance	358,915	161,235
Total Recorded Investment, Impaired Loans	433,991	208,054
Total Unpaid Principal Balance, Impaired Loans	515,864	285,891
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	300,836	218,230	$ 224,131
Interest Income Recognized While on Impaired Status	17,653	9,453	9,651
Commercial real estate
With an allowance recorded:
Recorded Investment	26,003	25,136
Unpaid Principal Balance	26,297	25,223
Related Allowance	4,159	3,668
With no allowance recorded:
Recorded Investment	28,272	15,764
Unpaid Principal Balance	66,631	58,141
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	42,374	54,434	42,347
Interest Income Recognized While on Impaired Status	2,339	2,815	2,163
Agriculture
With an allowance recorded:
Recorded Investment	98,392	60,053
Unpaid Principal Balance	104,350	76,874
Related Allowance	8,234	9,590
With no allowance recorded:
Recorded Investment	231,087	77,172
Unpaid Principal Balance	255,308	80,355
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	223,146	127,483	131,026
Interest Income Recognized While on Impaired Status	13,093	4,767	5,503
Commercial non-real estate
With an allowance recorded:
Recorded Investment	21,331	14,177
Unpaid Principal Balance	21,777	17,241
Related Allowance	6,062	4,508
With no allowance recorded:
Recorded Investment	21,579	8,905
Unpaid Principal Balance	31,414	18,047
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	28,196	28,938	41,489
Interest Income Recognized While on Impaired Status	1,791	1,405	1,485
Residential real estate
With an allowance recorded:
Recorded Investment	3,829	4,509
Unpaid Principal Balance	4,311	5,153
Related Allowance	1,795	2,210
With no allowance recorded:
Recorded Investment	3,290	2,177
Unpaid Principal Balance	5,454	4,574
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	6,889	7,156	8,900
Interest Income Recognized While on Impaired Status	410	452	453
Consumer
With an allowance recorded:
Recorded Investment	207	160
Unpaid Principal Balance	214	165
Related Allowance	97	61
With no allowance recorded:
Recorded Investment	1	1
Unpaid Principal Balance	108	118
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	231	219	369
Interest Income Recognized While on Impaired Status	$ 20	$ 14	$ 47

Loans - Troubled Debt Restructu

Loans - Troubled Debt Restructurings on Accruing and Nonaccrual Financing Receivables (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2019USD ($)contract	Sep. 30, 2018USD ($)contract	Sep. 30, 2017USD ($)contract
Accruing
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 44,842	$ 19,783
Financing receivable, modifications, number of contracts | contract	22	7	26
Financing receivable, modifications, pre-modification recorded investment	$ 28,636	$ 12,867	$ 24,689
Financing receivable, modifications, post-modification recorded investment	$ 28,636	$ 12,867	$ 24,689
Change in recorded investment due to principal paydown at time of modification, number of contracts | contract	0	0	0
Change in recorded investment due to principal paydown at time of modification, pre-modification	$ 0	$ 0	$ 0
Change in recorded investment due to principal paydown at time of modification, post-modification	$ 0	$ 0	$ 0
Change in recorded investment due to chargeoffs at time of modification, number of contracts | contract	0	0	0
Change in recorded investment due to chargeoffs at time of modification, pre-modification	$ 0	$ 0	$ 0
Change in recorded investment due to chargeoffs at time of modification, post-modification	0	0	$ 0
Nonaccrual
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 30,073	$ 77,156
Financing receivable, modifications, number of contracts | contract	12	9	26
Financing receivable, modifications, pre-modification recorded investment	$ 10,383	$ 9,990	$ 24,139
Financing receivable, modifications, post-modification recorded investment	$ 10,383	$ 9,990	$ 24,139
Change in recorded investment due to principal paydown at time of modification, number of contracts | contract	0	0	0
Change in recorded investment due to principal paydown at time of modification, pre-modification	$ 0	$ 0	$ 0
Change in recorded investment due to principal paydown at time of modification, post-modification	$ 0	$ 0	$ 0
Change in recorded investment due to chargeoffs at time of modification, number of contracts | contract	0	0	0
Change in recorded investment due to chargeoffs at time of modification, pre-modification	$ 0	$ 0	$ 0
Change in recorded investment due to chargeoffs at time of modification, post-modification	0	0	$ 0
Commercial real estate | Accruing
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 17,145	$ 2,649
Financing receivable, modifications, number of contracts | contract	2	1	2
Financing receivable, modifications, pre-modification recorded investment	$ 15,466	$ 2,041	$ 3,726
Financing receivable, modifications, post-modification recorded investment	15,466	2,041	$ 3,726
Commercial real estate | Nonaccrual
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 904	$ 2,616
Financing receivable, modifications, number of contracts | contract	1	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 882	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	882	0	$ 0
Agriculture | Accruing
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 22,929	$ 13,248
Financing receivable, modifications, number of contracts | contract	16	5	13
Financing receivable, modifications, pre-modification recorded investment	$ 11,537	$ 10,753	$ 18,902
Financing receivable, modifications, post-modification recorded investment	11,537	10,753	$ 18,902
Agriculture | Nonaccrual
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 24,762	$ 73,741
Financing receivable, modifications, number of contracts | contract	9	9	18
Financing receivable, modifications, pre-modification recorded investment	$ 5,802	$ 9,990	$ 20,197
Financing receivable, modifications, post-modification recorded investment	5,802	9,990	$ 20,197
Commercial non-real estate | Accruing
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 4,398	$ 3,420
Financing receivable, modifications, number of contracts | contract	2	0	9
Financing receivable, modifications, pre-modification recorded investment	$ 1,445	$ 0	$ 2,044
Financing receivable, modifications, post-modification recorded investment	1,445	0	$ 2,044
Commercial non-real estate | Nonaccrual
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 4,257	$ 656
Financing receivable, modifications, number of contracts | contract	2	0	3
Financing receivable, modifications, pre-modification recorded investment	$ 3,699	$ 0	$ 3,788
Financing receivable, modifications, post-modification recorded investment	3,699	0	$ 3,788
Residential real estate | Accruing
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 263	$ 389
Financing receivable, modifications, number of contracts | contract	0	0	1
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 9
Financing receivable, modifications, post-modification recorded investment	0	0	$ 9
Residential real estate | Nonaccrual
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 102	$ 143
Financing receivable, modifications, number of contracts | contract	0	0	2
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 133
Financing receivable, modifications, post-modification recorded investment	0	0	$ 133
Consumer | Accruing
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 107	$ 77
Financing receivable, modifications, number of contracts | contract	2	1	1
Financing receivable, modifications, pre-modification recorded investment	$ 188	$ 73	$ 8
Financing receivable, modifications, post-modification recorded investment	188	73	$ 8
Consumer | Nonaccrual
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 48	$ 0
Financing receivable, modifications, number of contracts | contract	0	0	3
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 21
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 21

Loans - Subsequent Defaults on

Loans - Subsequent Defaults on Modified Loans (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2019USD ($)contract	Sep. 30, 2018USD ($)contract	Sep. 30, 2017USD ($)contract
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	1	1	3
Recorded Investment | $	$ 0	$ 366	$ 8,383
Commercial real estate
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	0	0	0
Recorded Investment | $	$ 0	$ 0	$ 0
Agriculture
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	0	1	2
Recorded Investment | $	$ 0	$ 366	$ 8,383
Commercial non-real estate
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	0	0	1
Recorded Investment | $	$ 0	$ 0	$ 0
Residential real estate
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	0	0	0
Recorded Investment | $	$ 0	$ 0	$ 0
Consumer
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	1	0	0
Recorded Investment | $	$ 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	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	$ 64,540	$ 63,503	$ 64,642
Charge-offs	(37,061)	(19,904)	(25,880)
Recoveries	2,348	2,955	3,202
Provision	41,506	17,754	22,210
Allowance for loan losses, ending balance	70,774	64,540	63,503
Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	1,206
(Improvement) impairment of ASC 310-30 loans	(559)	232	(671)
Allowance for loan losses, ending balance	565	1,206
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	16,777	16,941	17,946
Charge-offs	(1,511)	(3,925)	(2,043)
Recoveries	567	533	485
Provision	1,514	3,231	643
Allowance for loan losses, ending balance	16,827	16,777	16,941
Commercial real estate | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	679
(Improvement) impairment of ASC 310-30 loans	(520)	(3)	(90)
Allowance for loan losses, ending balance	159	679
Agriculture
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	28,121	25,757	25,115
Charge-offs	(24,847)	(9,473)	(7,853)
Recoveries	385	332	415
Provision	27,160	11,355	7,965
Allowance for loan losses, ending balance	30,819	28,121	25,757
Agriculture | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	265
(Improvement) impairment of ASC 310-30 loans	0	150	115
Allowance for loan losses, ending balance	265	265
Commercial non-real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	13,610	14,114	12,990
Charge-offs	(7,895)	(3,813)	(12,576)
Recoveries	392	994	652
Provision	11,431	2,315	13,048
Allowance for loan losses, ending balance	17,567	13,610	14,114
Commercial non-real estate | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	0
(Improvement) impairment of ASC 310-30 loans	29	0	0
Allowance for loan losses, ending balance	29	0
Residential real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	4,749	5,347	7,106
Charge-offs	(998)	(569)	(809)
Recoveries	468	337	507
Provision	(56)	(451)	(761)
Allowance for loan losses, ending balance	4,095	4,749	5,347
Residential real estate | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	262
(Improvement) impairment of ASC 310-30 loans	(68)	85	(696)
Allowance for loan losses, ending balance	112	262
Consumer
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	257	329	438
Charge-offs	(452)	(192)	(196)
Recoveries	174	141	102
Provision	448	(21)	(15)
Allowance for loan losses, ending balance	427	257	329
Consumer | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	0
(Improvement) impairment of ASC 310-30 loans	0	0	0
Allowance for loan losses, ending balance	0	0
Other
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	1,026	1,015	1,047
Charge-offs	(1,358)	(1,932)	(2,403)
Recoveries	362	618	1,041
Provision	1,009	1,325	1,330
Allowance for loan losses, ending balance	1,039	1,026	1,015
Other | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	0
(Improvement) impairment of ASC 310-30 loans	0	0	$ 0
Allowance for loan losses, ending balance	$ 0	$ 0

Allowance for Loan and Lease _4

Allowance for Loan and Lease Losses - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and written loan commitments at fair value under the fair value option	$ 812,991	$ 865,386
Loan held for sale	7,351	5,456
Guaranteed loans	8,752,832	8,396,314
Allowance for loan losses	70,774	64,540	$ 63,503	$ 64,642
Unfunded loan commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Reserve for unfunded loan commitments	500	500
Receivables acquired with deteriorated credit quality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Guaranteed loans	55,819	70,845
Allowance for loan losses	565	1,206
(Improvement) impairment of ASC 310-30 loans	(559)	232	$ (671)
Loans Guaranteed by US Government Authorities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Guaranteed loans	154,200	168,600
Loans Guaranteed by US Government Authorities | Loans and Leases with Allowance for Doubtful Accounts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Guaranteed loans	$ 145,900	$ 160,300

Allowance for Loan and Lease _5

Allowance for Loan and Lease Losses - Summary of Allowance for Loan Losses by Type (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	$ 20,347	$ 20,037
Collectively evaluated for impairment	49,862	43,297
Total allowance	70,774	64,540	$ 63,503	$ 64,642
Financing Receivables
Individually evaluated for impairment	433,991	208,054
Collectively evaluated for impairment	8,263,022	8,117,415
Loans Outstanding	8,752,832	8,396,314
Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	565	1,206
Financing Receivables
Loans Outstanding	55,819	70,845
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	4,159	3,668
Collectively evaluated for impairment	12,509	12,430
Total allowance	16,827	16,777	16,941	17,946
Financing Receivables
Individually evaluated for impairment	54,275	40,900
Collectively evaluated for impairment	4,418,611	4,053,712
Loans Outstanding	4,495,010	4,121,613
Commercial real estate | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	159	679
Financing Receivables
Loans Outstanding	22,124	27,001
Agriculture
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	8,234	9,590
Collectively evaluated for impairment	22,320	18,266
Total allowance	30,819	28,121	25,757	25,115
Financing Receivables
Individually evaluated for impairment	329,479	137,225
Collectively evaluated for impairment	1,501,164	1,823,947
Loans Outstanding	1,833,399	1,963,987
Agriculture | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	265	265
Financing Receivables
Loans Outstanding	2,756	2,815
Commercial non-real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	6,062	4,508
Collectively evaluated for impairment	11,476	9,102
Total allowance	17,567	13,610	14,114	12,990
Financing Receivables
Individually evaluated for impairment	42,910	23,082
Collectively evaluated for impairment	1,480,949	1,364,511
Loans Outstanding	1,524,080	1,388,009
Commercial non-real estate | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	29	0
Financing Receivables
Loans Outstanding	221	416
Residential real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	1,795	2,210
Collectively evaluated for impairment	2,188	2,277
Total allowance	4,095	4,749	5,347	7,106
Financing Receivables
Individually evaluated for impairment	7,119	6,686
Collectively evaluated for impairment	763,645	780,047
Loans Outstanding	801,044	826,758
Residential real estate | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	112	262
Financing Receivables
Loans Outstanding	30,280	40,025
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	97	61
Collectively evaluated for impairment	330	196
Total allowance	427	257	329	438
Financing Receivables
Individually evaluated for impairment	208	161
Collectively evaluated for impairment	51,112	48,711
Loans Outstanding	51,758	49,460
Consumer | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	0	0
Financing Receivables
Loans Outstanding	438	588
Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	1,039	1,026
Total allowance	1,039	1,026	$ 1,015	$ 1,047
Financing Receivables
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	47,541	46,487
Loans Outstanding	47,541	46,487
Other | Receivables acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	0	0
Financing Receivables
Loans Outstanding	$ 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	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	$ 34,973	$ 44,131	$ 38,124
Accretion	(9,202)	(13,193)	(13,847)
Reclassification from nonaccretable difference	276	4,035	19,854
Balance at end of period	$ 26,047	$ 34,973	$ 44,131

Accounting for Certain Loans _4

Accounting for Certain Loans Acquired with Deteriorated Credit Quality - Schedule of Impaired Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	$ 137,853	$ 160,379
Recorded Investment	55,819	70,845
Carrying Value	55,254	69,640
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	90,295	100,761
Recorded Investment	22,124	27,001
Carrying Value	21,965	26,322
Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	4,462	4,841
Recorded Investment	2,756	2,815
Carrying Value	2,491	2,551
Commercial non-real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	7,190	7,475
Recorded Investment	221	416
Carrying Value	192	416
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	35,413	46,646
Recorded Investment	30,280	40,025
Carrying Value	30,168	39,763
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	493	656
Recorded Investment	438	588
Carrying Value	$ 438	$ 588

FDIC Indemnification Asset - Sc

FDIC Indemnification Asset - Schedule of Other Current Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
FDIC Indemnification Asset [Roll Forward]
Balance, beginning of period	$ 2,502	$ 5,704	$ 10,777
Amortization	(1,386)	(2,778)	(4,748)
Changes in expected reimbursements from FDIC for changes in expected credit losses	(10)	(122)	(45)
Changes in reimbursable expenses	(41)	(1,072)	(986)
Payments of covered losses to the FDIC	14	770	706
Balance, end of period	$ 1,079	$ 2,502	$ 5,704

Premises and Equipment - Schedu

Premises and Equipment - Schedule of Premises and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 157,192	$ 146,780
Accumulated depreciation	(36,547)	(32,941)
Premise and equipment, net	120,645	113,839
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	31,107	25,598
Buildings and building improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	95,778	85,960
Furniture and equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	26,688	27,490
Construction in progress
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 3,619	$ 7,732

Premises and Equipment - Narrat

Premises and Equipment - Narrative (Details) - USD ($)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 7,600,000	$ 7,500,000	$ 7,600,000
Property held for sale	2,757,000	1,104,000
Impairment charges recognized	$ 0	$ 0

Derivative Financial Instrume_3

Derivative Financial Instruments - Notional Amounts and Estimated Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Derivative [Line Items]
Gross Asset Fair Value	$ 48,700	$ 24,257
Gross Liability Fair Value	(38,826)	(4,863)
Derivatives Not Designated as Hedging Instruments
Derivative [Line Items]
Notional Amount	1,934,978	1,386,650
Gross Asset Fair Value	48,700	24,257
Gross Liability Fair Value	(38,826)	(4,863)
Derivatives Not Designated as Hedging Instruments | Risk participation agreements
Derivative [Line Items]
Notional Amount	56,833	37,351
Gross Asset Fair Value	0	0
Gross Liability Fair Value	(58)	(444)
Derivatives Not Designated as Hedging Instruments | Mortgage loan commitments
Derivative [Line Items]
Notional Amount	56,665	22,195
Gross Asset Fair Value	0	0
Gross Liability Fair Value	(11)	(28)
Derivatives Not Designated as Hedging Instruments | Mortgage loan forward sale contracts
Derivative [Line Items]
Notional Amount	61,872	27,408
Gross Asset Fair Value	11	28
Gross Liability Fair Value	0	0
Financial institution counterparties | Derivatives Not Designated as Hedging Instruments | Interest rate swaps
Derivative [Line Items]
Notional Amount	1,259,765	1,082,630
Gross Asset Fair Value	35	22,696
Gross Liability Fair Value	(38,755)	(2,231)
Financial institution counterparties | Derivatives Not Designated as Hedging Instruments | Interest rate caps
Derivative [Line Items]
Notional Amount	100	0
Gross Asset Fair Value	2	0
Gross Liability Fair Value	0	0
Customer counterparties | Derivatives Not Designated as Hedging Instruments | Interest rate swaps
Derivative [Line Items]
Notional Amount	499,643	217,066
Gross Asset Fair Value	48,652	1,533
Gross Liability Fair Value	0	(2,160)
Customer counterparties | Derivatives Not Designated as Hedging Instruments | Interest rate caps
Derivative [Line Items]
Notional Amount	100	0
Gross Asset Fair Value	0	0
Gross Liability Fair Value	$ (2)	$ 0

Derivative Financial Instrume_4

Derivative Financial Instruments - Offsetting Liabilities and Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative financial assets, gross amount	$ 48,700	$ 24,257
Derivative financial assets, amount offset	(2,445)	(2,231)
Derivative financial assets, cash collateral	12,279	(20,115)
Derivative financial assets, net amount presented in Consolidated Balance Sheets	58,534	1,911
Derivative financial liabilities, gross amount	(38,826)	(4,863)
Derivative financial liabilities, amount offset	2,445	2,231
Derivative financial liabilities, cash collateral	36,368	0
Derivative financial liabilities, net amount presented in Consolidated Balance Sheets	(13)	(2,632)
Collateral held for initial margin	$ 18,300	$ 6,200

Derivative Financial Instrume_5

Derivative Financial Instruments - Narrative (Details) - Risk participation agreements - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
Derivative [Line Items]
Notional amount sold	$ 56.8	$ 37.4
Exposure from RPAs	$ 0.1	$ 0.4

Derivative Financial Instrume_6

Derivative Financial Instruments - Effect on the Consolidated Statement of Comprehensive Income (Details) - Noninterest income - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Interest rate swaps
Derivative [Line Items]
Amount of gain (loss) recognized in income	$ (63,444)	$ 44,596	$ 49,900
Mortgage loan commitments
Derivative [Line Items]
Amount of gain (loss) recognized in income	17	(28)	(48)
Mortgage loan forward sale contracts
Derivative [Line Items]
Amount of gain (loss) recognized in income	$ (17)	$ 28	$ 48

The Fair Value Option For Cer_2

The Fair Value Option For Certain Loans - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Eligible item for the fair value option	$ 34,200	$ (34,800)
Loans greater than 90 days past due or in nonaccrual status	16,500	30,900
Loans greater than 90 days past due or in nonaccrual status, unpaid principal balance	17,800	34,700
Net increase (decrease) in fair value of loans at fair value	61,412	(45,407)	$ (65,231)
Long-term loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Eligible item for the fair value option	7,700	200	900
Fair value, option, aggregate differences, long-term debt instruments	778,800	900,200
Long-term loans | Noninterest Income (Loss)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net increase (decrease) in fair value of loans at fair value	$ 61,400	$ (45,400)	$ (65,200)

Goodwill - Summary of Changes t

Goodwill - Summary of Changes to the Carrying Amount of Goodwill (Details) - USD ($)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 739,023,000	$ 739,023,000
Impairment of goodwill	$ 0	$ 0	$ 0

Core Deposits and Other Intan_3

Core Deposits and Other Intangibles - Intangible Assets Amortization Expense (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 16,341	$ 16,341
Accumulated amortization	(10,167)	(8,629)
Net intangible assets	6,174	7,712
Core Deposit Intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	7,339	7,339
Accumulated amortization	(3,518)	(2,610)
Net intangible assets	3,821	4,729
Brand Intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	8,464	8,464
Accumulated amortization	(6,392)	(5,828)
Net intangible assets	2,072	2,636
Other Intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	538	538
Accumulated amortization	(257)	(191)
Net intangible assets	$ 281	$ 347

Core Deposits and Other Intan_4

Core Deposits and Other Intangibles - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 1.5	$ 1.7	$ 2.4

Core Deposits and Other Intan_5

Core Deposits and Other Intangibles - Schedule of Future Amortization Expense (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2020	$ 1,430
2021	1,334
2022	1,249
2023	967
2024	498
2025 and thereafter	696
Net intangible assets	$ 6,174	$ 7,712

Deposits - Composition of Depos

Deposits - Composition of Deposits (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Composition of deposits:
Noninterest-bearing demand	$ 1,956,025	$ 1,842,704
Interest-bearing demand	6,248,638	6,043,717
Time deposits, greater than $250,000	493,530	383,868
Time deposits, less than or equal to $250,000	1,602,146	1,463,210
Total deposits	10,300,339	9,733,499
Brokered deposits	$ 706,500	$ 600,200

Deposits - Summary of Scheduled

Deposits - Summary of Scheduled Maturities of Time Deposits (Details) $ in Thousands	Sep. 30, 2019USD ($)
Fiscal year maturity:
2020	$ 1,746,896
2021	250,248
2022	60,337
2023	26,858
2024	11,026
2025 and thereafter	311
Total	$ 2,095,676

Securities Sold Under Agreeme_3

Securities Sold Under Agreements to Repurchase - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities sold under agreements to repurchase, amortized cost	$ 94.7	$ 109.9
Securities sold under agreements to repurchase, fair value	$ 94.4	$ 104.6
Percentage of total 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	Sep. 30, 2019	Sep. 30, 2018
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	$ 68,992	$ 90,907
Mortgage-backed securities
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	68,992	90,907
Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	68,992	90,907
Overnight and Continuous | Mortgage-backed securities
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	68,992	90,907
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 - Summary of Advances and Other Borrowings (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Debt Instrument [Line Items]
FHLB advances and other borrowings	$ 340,000	$ 275,000
Notes payable to banks
Debt Instrument [Line Items]
Federal Home Loan Bank (FHLB) notes payable and fed funds advance	$ 325,000	175,000
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%
Federal Home Loan Bank fed funds advance
Debt Instrument [Line Items]
Interest rate (as a percent)	2.09%
Federal Home Loan Bank (FHLB) notes payable and fed funds advance	$ 15,000	$ 100,000

FHLB Advances and Other Borro_4

FHLB Advances and Other Borrowings - Narrative (Details) - USD ($)	Sep. 30, 2019	Sep. 30, 2018
Line of Credit Facility [Line Items]
Current borrowing capacity	$ 1,800,000,000	$ 1,820,000,000
Loans pledged to the Federal Home Loan Bank	4,200,000,000	3,950,000,000
Revolving line of credit | FRB Discount Window Loan
Line of Credit Facility [Line Items]
Borrowing capacity	1,440,000,000	1,590,000,000
Loans pledged to the Federal Reserve Board Discount Window	1,720,000,000	1,890,000,000
FHLB | Letters of credit
Line of Credit Facility [Line Items]
Borrowing capacity	170,000,000	150,000,000
FHLB | Additional Letters of Credit
Line of Credit Facility [Line Items]
Borrowing capacity	$ 14,900,000	$ 16,400,000

FHLB Advances and Other Borro_5

FHLB Advances and Other Borrowings - Summary of Due or Callable Notes (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Debt Instrument [Line Items]
Total	$ 108,636	$ 108,468
FHLB Advances and Other Borrowings
Debt Instrument [Line Items]
2020	15,000
2021	120,000
2022	60,000
2023	85,000
2024	60,000
2025 and thereafter	0
Total	$ 340,000

Subordinated Debentures and S_3

Subordinated Debentures and Subordinated Notes Payable - Junior Subordinated Deferrable Interest Debentures (Details) $ / shares in Units, $ in Thousands	Jul. 05, 2007$ / sharesshares	Dec. 07, 2006$ / sharesshares	Mar. 10, 2006$ / sharesshares	Jun. 01, 2005$ / sharesshares	Dec. 17, 2003$ / sharesshares	Sep. 25, 2003$ / sharesshares	Dec. 19, 2002$ / sharesshares	Dec. 31, 2016shares	Sep. 30, 2019USD ($)trust	Sep. 30, 2018USD ($)
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Amount of Debentures eligible for treatment as Tier 1 capital | $									$ 108,636	$ 108,468
Mandatorily Redeemable Preferred Securities
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Number of trusts | trust									7
Mandatorily Redeemable Preferred Securities | Great Western Statutory Trust IV
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Number of shares caused to be issued | shares					22,400
Par value of shares issued (in dollars per share)					$ 1,000
Maximum interest payment deferral period					5 years
Term of debt instrument					30 years
Redemption price (in dollars per share)					$ 1,000
Mandatorily Redeemable Preferred Securities | GWB Capital Trust VI
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Number of shares caused to be issued | shares			30,000
Par value of shares issued (in dollars per share)			$ 1,000
Maximum interest payment deferral period			5 years
Redemption price (in dollars per share)			$ 1,000
Mandatorily Redeemable Preferred Securities | GWB Capital Trust II
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Stated interest rate (as a percent)			9.75%
Mandatorily Redeemable Preferred Securities | Sunstate Bancshares Trust II
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Number of shares caused to be issued | shares				2,000
Par value of shares issued (in dollars per share)				$ 1,000
Maximum interest payment deferral period				5 years
Redemption period following the occurrence of a Special Event				90 days
Redemption price (in dollars per share)				$ 1,000
Mandatorily Redeemable Preferred Securities | HFB Capital Trust III
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Number of shares caused to be issued | shares							5,000
Par value of shares issued (in dollars per share)							$ 1,000
Maximum interest payment deferral period							5 years
Redemption period following the occurrence of a Special Event							90 days
Redemption price (in dollars per share)							$ 1,000
Mandatorily Redeemable Preferred Securities | HFB Capital Trust IV
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Number of shares caused to be issued | shares						7,000
Par value of shares issued (in dollars per share)						$ 1,000
Maximum interest payment deferral period						5 years
Redemption period following the occurrence of a Special Event						90 days
Redemption price (in dollars per share)						$ 1,000
Mandatorily Redeemable Preferred Securities | HFB Capital Trust V
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Number of shares caused to be issued | shares		10,000
Par value of shares issued (in dollars per share)		$ 1,000
Maximum interest payment deferral period		5 years
Redemption period following the occurrence of a Special Event		90 days
Redemption price (in dollars per share)		$ 1,000
Number of shares redeemed (in shares) | shares								5,000
Mandatorily Redeemable Preferred Securities | HFB Capital Trust VI
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Number of shares caused to be issued | shares	2,000
Par value of shares issued (in dollars per share)	$ 1,000
Maximum interest payment deferral period	5 years
Redemption period following the occurrence of a Special Event	90 days
Redemption price (in dollars per share)	$ 1,000
Mandatorily Redeemable Preferred Securities | London Interbank Offered Rate (LIBOR) | Great Western Statutory Trust IV
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Basis spread on variable rate (as a percent)					2.85%
Mandatorily Redeemable Preferred Securities | London Interbank Offered Rate (LIBOR) | GWB Capital Trust VI
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Basis spread on variable rate (as a percent)			1.48%
Mandatorily Redeemable Preferred Securities | London Interbank Offered Rate (LIBOR) | Sunstate Bancshares Trust II
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Basis spread on variable rate (as a percent)				1.85%
Mandatorily Redeemable Preferred Securities | London Interbank Offered Rate (LIBOR) | HFB Capital Trust III
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Basis spread on variable rate (as a percent)							3.35%
Mandatorily Redeemable Preferred Securities | London Interbank Offered Rate (LIBOR) | HFB Capital Trust IV
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Basis spread on variable rate (as a percent)						3.10%
Mandatorily Redeemable Preferred Securities | London Interbank Offered Rate (LIBOR) | HFB Capital Trust V
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Basis spread on variable rate (as a percent)		1.83%
Mandatorily Redeemable Preferred Securities | London Interbank Offered Rate (LIBOR) | HFB Capital Trust VI
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Basis spread on variable rate (as a percent)	1.65%
Junior subordinated debentures payable to non-consolidated trusts
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Amount of Debentures eligible for treatment as Tier 1 capital | $									$ 73,697	73,603
Common shares held in other assets | $									$ 2,520	$ 2,520
HFB Capital Trust V | Junior subordinated debentures payable to non-consolidated trusts
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Basis spread on variable rate (as a percent)									1.83%	1.83%
Common shares held in other assets | $									$ 310	$ 310

Subordinated Debentures and S_4

Subordinated Debentures and Subordinated Notes Payable - Subordinated Notes Payable (Details) - Subordinated notes payable - USD ($)	12 Months Ended	60 Months Ended
	Sep. 30, 2019	Aug. 15, 2025	Sep. 30, 2018
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	$ 61,000		$ 135,000
London Interbank Offered Rate (LIBOR) | Forecast
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 Subordinated Notes Payable (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Debt Instrument [Line Items]
Total	$ 108,636	$ 108,468
Junior subordinated debentures payable to non-consolidated trusts
Debt Instrument [Line Items]
Amount Outstanding	75,920	75,920
Common Shares Held in Other Assets	2,520	2,520
Less: fair value adjustment	(2,223)	(2,317)
Total	$ 73,697	73,603
Subordinated notes payable
Debt Instrument [Line Items]
Stated interest rate (as a percent)	4.875%
Unamortized debt issuance costs	$ (61)	(135)
Total	34,939	34,865
GW Statutory Trust IV | Junior subordinated debentures payable to non-consolidated trusts
Debt Instrument [Line Items]
Amount Outstanding	23,093	23,093
Common Shares Held in Other Assets	$ 693	$ 693
Basis spread on variable rate (as a percent)	2.85%	2.85%
GW Statutory Trust VI | Junior subordinated debentures payable to non-consolidated trusts
Debt Instrument [Line Items]
Amount Outstanding	$ 30,928	$ 30,928
Common Shares Held in Other Assets	$ 928	$ 928
Basis spread on variable rate (as a percent)	1.48%	1.48%
SSB Trust II | Junior subordinated debentures payable to non-consolidated trusts
Debt Instrument [Line Items]
Amount Outstanding	$ 2,062	$ 2,062
Common Shares Held in Other Assets	$ 62	$ 62
Basis spread on variable rate (as a percent)	1.85%	1.85%
HFB Capital Trust III | Junior subordinated debentures payable to non-consolidated trusts
Debt Instrument [Line Items]
Amount Outstanding	$ 5,155	$ 5,155
Common Shares Held in Other Assets	$ 155	$ 155
Basis spread on variable rate (as a percent)	3.35%	3.35%
HFB Capital Trust IV | Junior subordinated debentures payable to non-consolidated trusts
Debt Instrument [Line Items]
Amount Outstanding	$ 7,217	$ 7,217
Common Shares Held in Other Assets	$ 217	$ 217
Basis spread on variable rate (as a percent)	3.10%	3.10%
HFB Capital Trust V | Junior subordinated debentures payable to non-consolidated trusts
Debt Instrument [Line Items]
Amount Outstanding	$ 5,310	$ 5,310
Common Shares Held in Other Assets	$ 310	$ 310
Basis spread on variable rate (as a percent)	1.83%	1.83%
HFB Capital Trust VI | Junior subordinated debentures payable to non-consolidated trusts
Debt Instrument [Line Items]
Amount Outstanding	$ 2,155	$ 2,155
Common Shares Held in Other Assets	$ 155	$ 155
Basis spread on variable rate (as a percent)	1.65%	1.65%
Subordinated notes payable, fixed to floating rate | Subordinated notes payable
Debt Instrument [Line Items]
Amount Outstanding	$ 35,000	$ 35,000
Stated interest rate (as a percent)	4.875%	4.875%

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Currently paid or payable
Federal	$ 30,779	$ 42,261	$ 56,171
State	9,327	10,556	10,639
Total	40,106	52,817	66,810
Deferred tax expense
Federal	7,507	20,205	2,477
State	617	1,097	154
Total	8,124	21,302	2,631
Total provision for income taxes	$ 48,230	$ 74,119	$ 69,441

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income tax percentage (as a percent)		24.50%
Income tax expense computed at the statutory rate	$ 45,275	$ 56,915	$ 74,979
State income taxes, net of federal benefit	7,855	8,795	7,015
Tax exempt interest income	(5,193)	(5,778)	(7,973)
Tax benefit of stock-based compensation plans	(91)	(424)	(2,153)
Impact of enacted federal income tax rate reduction	0	13,709	0
Other	384	902	(2,427)
Total provision for income taxes	$ 48,230	$ 74,119	$ 69,441

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Deferred tax assets:
Allowance for loan and lease losses	$ 17,214	$ 15,709
Compensation	4,017	2,577
Securities available for sale	0	10,305
Other real estate owned	574	325
Core deposit intangible and other fair value adjustments	3,868	3,677
Excess tax basis of FDIC indemnification asset and clawback liability	4,095	3,633
Excess tax basis of loans acquired over carrying value	2,656	3,669
Other reserves	2,926	2,787
Other	6,350	5,711
Total deferred tax assets	41,700	48,393
Deferred tax liabilities:
Goodwill and other intangibles	(15,064)	(11,567)
Securities available for sale	(4,419)	0
Premises and equipment	(5,869)	(6,248)
Deferred REIT income	(8,783)	0
Other	(279)	(446)
Total deferred tax liabilities	(34,414)	(18,261)
Net deferred tax assets	$ 7,286	$ 30,132

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
		Dec. 31, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Contingency [Line Items]
Income tax percentage (as a percent)					24.50%
Provision (benefit) for income taxes					$ 19,700
Revaluation adjustment		$ 13,600
Reclassification from AOCI to retained earnings	[1]				0
Internal Revenue Service (IRS)
Income Tax Contingency [Line Items]
Income taxes receivable				$ (8,400)	(3,500)
Retained Earnings
Income Tax Contingency [Line Items]
Reclassification from AOCI to retained earnings	[1]				2,353
Accumulated Other Comprehensive Income (Loss)
Income Tax Contingency [Line Items]
Reclassification from AOCI to retained earnings			$ 2,400		$ (2,353)	[1]
Tax Cuts And Jobs Act Of 2017
Income Tax Contingency [Line Items]
Income tax percentage (as a percent)				22.40%	31.90%
Tax Cuts And Jobs Act Of 2017, Excluding Nonrecurring Deferred Taxes
Income Tax Contingency [Line Items]
Income tax percentage (as a percent)				22.40%	26.10%
[1]	Reclassification due to adoption of ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income .

Employee Benefit Plans - Narrat

Employee Benefit Plans - Narrative (Details) - Multiple employer 401(k) profit sharing plan $ in Millions	9 Months Ended	12 Months Ended
	Jun. 30, 2017USD ($)	Sep. 30, 2019USD ($)year	Sep. 30, 2018USD ($)
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, requisite service period		1 year
Defined contribution plan, minimum age requirement | year		21
Contributions by the Company | $	$ 5.3	$ 5.8	$ 5.7

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 5.9	$ 5.5	$ 6.5
Tax benefit from compensation expense	1.5	1.7	2.5
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, compensation cost not yet recognized	$ 5
Share-based compensation, compensation cost not yet recognized, recognition period	2 years 2 months 12 days
Share-based compensation, fair value of vested awards	$ 1.9	$ 1.9	$ 1.4

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Restricted and Performance Stock (Details) - $ / shares	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares, beginning balance (shares)	163,287	180,337	160,335
Granted (shares)	106,753	89,376	90,363
Vested and issued (shares)	(76,210)	(97,682)	(68,293)
Forfeited (shares)	(3,025)	(8,744)	(2,068)
Canceled (shares)	0	0	0
Shares, ending balance (shares)	190,805	163,287	180,337
Vested, but not issuable (shares)	50,770	39,514	29,287
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Shares, beginning balance (in USD per share)	$ 37.86	$ 33.06	$ 26.89
Granted (in USD per share)	37.27	41.07	39.35
Vested and issued (in USD per share)	38.64	32.11	26.97
Forfeited (in USD per share)	38.67	35.99	30.91
Canceled (in USD per share)	0	0	0
Shares, ending balance (in USD per share)	37.20	37.86	33.06
Vested, but not issuable (in USD per share)	$ 33.88	$ 32.90	$ 30.05
Performance shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares, beginning balance (shares)	175,196	133,604	236,185
Granted (shares)	60,583	53,682	137,612
Vested and issued (shares)	(59,937)	(7,017)	(235,055)
Forfeited (shares)	(2,510)	(5,073)	(5,138)
Canceled (shares)	0	0	0
Shares, ending balance (shares)	173,332	175,196	133,604
Vested, but not issuable (shares)	5,612	5,612	5,612
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Shares, beginning balance (in USD per share)	$ 36.29	$ 33.39	$ 20.28
Granted (in USD per share)	32.77	29.52	39.43
Vested and issued (in USD per share)	30.79	18	18
Forfeited (in USD per share)	39.25	37.75	19.80
Canceled (in USD per share)	0	0	0
Shares, ending balance (in USD per share)	38.50	36.29	33.39
Vested, but not issuable (in USD per share)	$ 18	$ 18	$ 18

Regulatory Matters - Summary of

Regulatory Matters - Summary of Capital Amounts and Ratios (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Tier 1 risk based capital (to risk-weighted assets):
For Capital Adequacy Purposes, Percentage	8.50%
Total risk based capital (to risk-weighted assets):
For Capital Adequacy Purposes, Percentage	10.50%
Common Equity Tier 1 risk based capital (to risk-weighted assets):
For Capital Adequacy Purposes, Percentage	7.00%
Great Western Bancorp, Inc.
Tier 1 risk based capital (to risk-weighted assets):
Actual, Amount	$ 1,225,355	$ 1,208,852
Actual, Percentage	11.70%	12.00%
For Capital Adequacy Purposes, Amount	$ 627,493	$ 604,637
For Capital Adequacy Purposes, Percentage	6.00%	6.00%
Total risk based capital (to risk-weighted assets):
Actual, Amount	$ 1,331,611	$ 1,308,875
Actual, Percentage	12.70%	13.00%
For Capital Adequacy Purposes, Amount	$ 836,658	$ 806,182
For Capital Adequacy Purposes, Percentage	8.00%	8.00%
Tier 1 leverage capital (to average assets):
Actual, Amount	$ 1,225,355	$ 1,208,852
Actual, Percentage	10.10%	10.70%
For Capital Adequacy Purposes, Actual	$ 483,487	$ 451,939
For Capital Adequacy Purposes, Percentage	4.00%	4.00%
Common Equity Tier 1 risk based capital (to risk-weighted assets):
Actual, Amount	$ 1,151,658	$ 1,135,249
Actual, Percentage	11.00%	11.30%
For Capital Adequacy Purposes, Actual	$ 470,620	$ 453,478
For Capital Adequacy Purposes, Percentage	4.50%	4.50%
Great Western Bank
Tier 1 risk based capital (to risk-weighted assets):
Actual, Amount	$ 1,201,476	$ 1,168,110
Actual, Percentage	11.50%	11.60%
For Capital Adequacy Purposes, Amount	$ 627,311	$ 604,467
For Capital Adequacy Purposes, Percentage	6.00%	6.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions, Actual	$ 836,415	$ 805,957
To Be Well Capitalized Under Prompt Corrective Action Provisions, Percentage	8.00%	8.00%
Total risk based capital (to risk-weighted assets):
Actual, Amount	$ 1,272,733	$ 1,233,133
Actual, Percentage	12.20%	12.20%
For Capital Adequacy Purposes, Amount	$ 836,415	$ 805,957
For Capital Adequacy Purposes, Percentage	8.00%	8.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 1,045,519	$ 1,007,446
To Be Well Capitalized Under Prompt Corrective Action Provisions, Percentage	10.00%	10.00%
Tier 1 leverage capital (to average assets):
Actual, Amount	$ 1,201,476	$ 1,168,110
Actual, Percentage	9.90%	10.30%
For Capital Adequacy Purposes, Actual	$ 483,957	$ 452,404
For Capital Adequacy Purposes, Percentage	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions, Actual	$ 604,946	$ 565,505
To Be Well Capitalized Under Prompt Corrective Action Provisions, Percentage	5.00%	5.00%
Common Equity Tier 1 risk based capital (to risk-weighted assets):
Actual, Amount	$ 1,201,476	$ 1,168,110
Actual, Percentage	11.50%	11.60%
For Capital Adequacy Purposes, Actual	$ 470,483	$ 453,351
For Capital Adequacy Purposes, Percentage	4.50%	4.50%
To Be Well Capitalized Under Prompt Corrective Action Provisions, Actual	$ 679,587	$ 654,840
To Be Well Capitalized Under Prompt Corrective Action Provisions, Percentage	6.50%	6.50%

Commitments and Contingencies -

Commitments and Contingencies - Summary of the Company's Commitments (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans repurchased during period	$ 3,300	$ 3,300
Commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments representing credit risk	2,229,678	2,344,550
Letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments representing credit risk	$ 68,983	$ 69,613

Commitments and Contingencies_2

Commitments and Contingencies - Lease Commitments (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Operating Leased Assets [Line Items]
Rent expense	$ 5,400	$ 5,400	$ 5,400
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2020	5,327
2021	4,193
2022	3,486
2023	3,068
2024	2,563
2025 and thereafter	7,355
Total	$ 25,992
Minimum
Operating Leased Assets [Line Items]
Operating leases, renewal term	1 year
Maximum
Operating Leased Assets [Line Items]
Operating leases, renewal term	10 years

Transactions with Related Par_2

Transactions with Related Parties - Narrative (Details) - USD ($)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Related Party Transaction [Line Items]
Interest on related party notes payable	$ 0	$ 0	$ 0
National Australia Bank Limited | Shares from former parent company | Salaries and employee benefits
Related Party Transaction [Line Items]
Expenses from transactions with related party			$ 100,000
National Australia Bank Limited | Shares from former parent company | Restricted shares | Accrued expenses and other liabilities
Related Party Transaction [Line Items]
Due to related parties	$ 0	$ 100,000

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value Measurements of Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	$ 1,783,208	$ 1,385,650
Fair value loans	812,991	865,386
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	94,745	167,172
Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,620,903	1,149,707
States and political subdivision securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	66,523	67,775
Fair value, measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,783,208	1,385,650
Derivatives-assets	58,534	1,911
Fair value of derivatives	13	2,632
Fair value loans	812,991	865,386
Loan servicing rights	2,255	3,087
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	94,745	167,172
Fair value, measurements, recurring | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,620,903	1,149,707
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	66,523	67,775
Fair value, measurements, recurring | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,037	996
Fair value, measurements, recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	94,745	167,172
Derivatives-assets	0	0
Fair value of derivatives	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	94,745	167,172
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	1,684,343	1,217,508
Derivatives-assets	58,534	1,911
Fair value of derivatives	13	2,632
Fair value loans	812,991	865,386
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	1,620,903	1,149,707
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	62,403	66,805
Fair value, measurements, recurring | Level 2 | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,037	996
Fair value, measurements, recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	4,120	970
Derivatives-assets	0	0
Fair value of derivatives	0	0
Fair value loans	0	0
Loan servicing rights	2,255	3,087
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	4,120	970
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 Other Available-for-Sale (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Available-for-sale securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 970	$ 1,069	$ 1,315
Additions	3,350	149	0
Principal paydown	(200)	(248)	(246)
Balance, end of period	4,120	970	1,069
Loan servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	3,087	4,074	5,781
Realized and unrealized loss	(832)	(987)	(1,707)
Balance, end of period	$ 2,255	$ 3,087	$ 4,074

Fair Value Measurements - Mortg

Fair Value Measurements - Mortgage Loans Held for Sale (Details) - Fair value, measurements, nonrecurring - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other repossessed property	$ 34,721	$ 22,225
Impaired loans	413,644	188,017
Loans held for sale, at lower of cost or fair value	7,351	5,456
Property held for sale	2,757	1,104
Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other repossessed property	0	0
Impaired loans	0	0
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
Loans held for sale, at lower of cost or fair value	7,351	5,456
Property held for sale	0	0
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other repossessed property	34,721	22,225
Impaired loans	413,644	188,017
Loans held for sale, at lower of cost or fair value	0	0
Property held for sale	$ 2,757	$ 1,104

Fair Value Measurements - Valua

Fair Value Measurements - Valuation Techniques and Significant Unobservable Inputs Used for Level 3 Measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Property held for sale	$ 2,757	$ 1,104
Fair value, measurements, nonrecurring
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other repossessed property	34,721	22,225
Impaired loans	413,644	188,017
Fair value, measurements, nonrecurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other repossessed property	34,721	22,225
Impaired loans	413,644	$ 188,017
Property held for sale	$ 2,757

Fair Value Measurements - Sch_3

Fair Value Measurements - Schedule of Balance Sheet Grouping Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Liabilities
Net deferred loan fees	$ 13,900	$ 13,000
Carrying Amount | Level 1
Assets [Abstract]
Cash and cash equivalents	243,474	298,696
Carrying Amount | Level 3
Assets [Abstract]
Loans, net, excluding fair valued loans, loans held for sale and impaired loans	8,472,777	8,357,065
Carrying Amount | Level 2
Liabilities
Time deposits	2,095,676	1,847,078
FHLB advances and other borrowings	340,000	275,000
Securities sold under repurchase agreements	68,992	90,907
Subordinated debentures and subordinated notes payable	108,636	108,468
Fair Value | Level 1
Assets [Abstract]
Cash and cash equivalents	243,474	298,696
Fair Value | Level 3
Assets [Abstract]
Loans, net, excluding fair valued loans, loans held for sale and impaired loans	8,533,612	8,231,829
Fair Value | Level 2
Liabilities
Time deposits	2,101,239	1,848,550
FHLB advances and other borrowings	351,517	275,797
Securities sold under repurchase agreements	68,992	90,907
Subordinated debentures and subordinated notes payable	$ 101,164	$ 107,841

Earnings per Share - Schedule o

Earnings per Share - Schedule of EPS, Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income	$ 167,365	$ 157,916	$ 144,786
Weighted average shares outstanding, basic (in shares)	57,154,865	58,938,169	58,770,708
Dilutive effect of stock based compensation (in shares)	102,196	193,481	258,674
Weighted average shares outstanding, diluted (in shares)	57,257,061	59,131,650	59,029,382
Basic earnings per share (in dollars per share)	$ 2.93	$ 2.68	$ 2.46
Diluted earnings per share (in dollars per share)	$ 2.92	$ 2.67	$ 2.45
Performance stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of earnings per share (in shares)	0	0
Stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of earnings per share (in shares)	18,006	0

Parent Company Only Financial_3

Parent Company Only Financial Statements - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Assets [Abstract]
Cash and cash equivalents	$ 243,474	$ 298,696	$ 360,396	$ 524,611
Net deferred tax assets	7,286	30,132
Other assets	132,417	85,601
Total assets	12,788,301	12,116,808
Liabilities and stockholders’ equity
Subordinated debentures and subordinated notes payable	108,636	108,468
Accrued expenses and other liabilities	70,085	68,383
Total liabilities	10,888,052	10,276,257
Stockholders’ equity
Common stock	563	589
Additional paid-in capital	1,228,714	1,318,457
Retained earnings	657,475	553,014
Accumulated other comprehensive income (loss)	13,497	(31,509)
Total stockholders' equity	1,900,249	1,840,551	1,755,000	1,663,391
Total liabilities and stockholders' equity	12,788,301	12,116,808
Great Western Bancorp, Inc.
Assets [Abstract]
Cash and cash equivalents	57,543	72,924	$ 15,004	$ 6,521
Investment in subsidiaries	1,950,077	1,873,422
Net deferred tax assets	1,716	1,489
Other assets	689	2,056
Total assets	2,010,025	1,949,891
Liabilities and stockholders’ equity
Subordinated debentures and subordinated notes payable	108,636	108,468
Accrued expenses and other liabilities	1,140	872
Total liabilities	109,776	109,340
Stockholders’ equity
Common stock	563	589
Additional paid-in capital	1,228,714	1,318,457
Retained earnings	657,475	553,014
Accumulated other comprehensive income (loss)	13,497	(31,509)
Total stockholders' equity	1,900,249	1,840,551
Total liabilities and stockholders' equity	$ 2,010,025	$ 1,949,891

Parent Company Only Financial_4

Parent Company Only Financial Statements - Condensed Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Income
Dividends on securities	$ 41,510	$ 29,171	$ 26,311
Expenses
Interest on subordinated debentures and subordinated notes payable	5,540	5,040	4,464
Salaries and employee benefits	136,305	135,352	128,135
Professional fees	14,579	17,891	15,038
Other	20,293	19,171	18,923
Income tax benefit	48,230	74,119	69,441
Net income	167,365	157,916	144,786
Great Western Bancorp, Inc.
Income
Dividends from subsidiary bank	148,128	111,159	62,470
Dividends on securities	19	51	123
Other	120	103	62
Total income	148,267	111,313	62,655
Expenses
Interest on subordinated debentures and subordinated notes payable	5,540	5,040	4,464
Salaries and employee benefits	6,288	5,849	6,847
Professional fees	1,035	1,038	631
Other	2,653	2,456	2,204
Total expense	15,516	14,383	14,146
Income before income tax and equity in undistributed net income of subsidiaries	132,751	96,930	48,509
Income tax benefit	(2,965)	(3,075)	(8,147)
Income before equity in undistributed net income of subsidiaries	135,716	100,005	56,656
Equity in undistributed net income of subsidiaries	31,649	57,911	88,130
Net income	$ 167,365	$ 157,916	$ 144,786

Parent Company Only Financial_5

Parent Company Only Financial Statements - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Operating activities
Net income	$ 167,365	$ 157,916	$ 144,786
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	13,655	13,093	13,599
Gain on redemption of subordinated debentures	0	0	(111)
Stock-based compensation	4,582	4,419	6,810
Deferred income taxes	8,124	21,302	2,631
Changes in:
Accrued interest payable and other liabilities	2,949	(2,742)	(64,517)
Net cash provided by operating activities	191,659	182,429	131,509
Financing activities
Redemption of subordinated debentures	0	0	(3,625)
Common stock repurchased	(94,351)	0	(5,605)
Dividends paid	(62,904)	(53,002)	(43,474)
Net cash provided by financing activities	451,587	289,182	83,469
Net decrease in cash and cash equivalents	(55,222)	(61,700)	(164,215)
Cash and cash equivalents, beginning of period	298,696	360,396	524,611
Cash and cash equivalents, end of period	243,474	298,696	360,396
Great Western Bancorp, Inc.
Operating activities
Net income	167,365	157,916	144,786
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	168	166	165
Gain on redemption of subordinated debentures	0	0	(111)
Stock-based compensation	4,582	4,419	6,810
Deferred income taxes	(227)	13	(1,796)
Changes in:
Other assets	1,367	6,459	(823)
Accrued interest payable and other liabilities	268	(140)	286
Equity in undistributed net income of subsidiaries	(31,649)	(57,911)	(88,130)
Net cash provided by operating activities	141,874	110,922	61,187
Financing activities
Redemption of subordinated debentures	0	0	(3,625)
Common stock repurchased	(94,351)	0	(5,605)
Dividends paid	(62,904)	(53,002)	(43,474)
Net cash provided by financing activities	(157,255)	(53,002)	(52,704)
Net decrease in cash and cash equivalents	(15,381)	57,920	8,483
Cash and cash equivalents, beginning of period	72,924	15,004	6,521
Cash and cash equivalents, end of period	$ 57,543	$ 72,924	$ 15,004

Uncategorized Items - gwb-20190

Label	Element	Value	[1]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 263,000
Additional Paid-in Capital [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	751,000
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (488,000)
[1]	Cumulative effect adjustment relates to adoption of ASU 2016-09, Compensation - Stock Based Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting.