Great Western Bancorp (GWB) 10-Q 9 May 17 2017 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Mar. 31, 2017	May 02, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	Great Western Bancorp, Inc.
Entity Central Index Key	1,613,665
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		58,760,964

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Assets
Cash and due from banks	$ 160,889	$ 142,152
Interest-bearing bank deposits	175,040	382,459
Cash and cash equivalents	335,929	524,611
Securities available for sale	1,350,893	1,317,386
Loans, net of unearned discounts and deferred fees, including $64,681 and $73,272 of loans covered by FDIC loss share agreements at March 31, 2017 and September 30, 2016, respectively, and $1,056,155 and $1,131,111 of loans and written loan commitments at fair value under the fair value option at March 31, 2017 and September 30, 2016, respectively, and $4,902 and $12,918 of loans held for sale at March 31, 2017 and September 30, 2016, respectively	8,697,426	8,682,644
Allowance for loan and lease losses	(62,685)	(64,642)
Net loans	8,634,741	8,618,002
Premises and equipment, including $5,258 and $8,112 of property held for sale at March 31, 2017 and September 30, 2016, respectively	114,166	118,506
Accrued interest receivable	43,690	49,531
Other repossessed property, including $0 and $106 of property covered by FDIC loss share agreements at March 31, 2017 and September 30, 2016, respectively	6,994	10,282
FDIC indemnification asset	8,371	10,777
Goodwill	739,023	739,023
Core deposits and other intangibles	10,343	11,732
Loan servicing rights	4,903	5,781
Cash surrender value of life insurance policies	29,188	29,166
Net deferred tax assets	46,159	38,346
Other assets	32,441	58,037
Total assets	11,356,841	11,531,180
Deposits
Noninterest-bearing	2,026,627	1,880,512
Interest-bearing	7,065,291	6,724,278
Total deposits	9,091,918	8,604,790
Securities sold under agreements to repurchase	124,472	141,688
FHLB advances and other borrowings	264,624	871,037
Subordinated debentures and subordinated notes payable	108,220	111,873
Fair value of derivatives	12,574	81,515
Accrued interest payable	3,983	4,074
Accrued expenses and other liabilities	44,189	52,812
Total liabilities	9,649,980	9,867,789
Stockholders’ equity
Common stock, $0.01 par value, authorized 500,000,000 shares; 58,760,517 shares issued and outstanding at March 31, 2017 and 58,693,304 shares issued and outstanding at September 30, 2016	587	587
Additional paid-in capital	1,315,934	1,312,347
Retained earnings	397,018	344,923
Accumulated other comprehensive income (loss)	(6,678)	5,534
Total stockholders' equity	1,706,861	1,663,391
Total liabilities and stockholders' equity	$ 11,356,841	$ 11,531,180

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Assets
Loans covered by FDIC loss share agreements	$ 64,681	$ 73,272
Loans and written loan commitments at fair value under the fair value option	1,056,155	1,131,111
Loan held for sale	4,902	12,918
Property held for sale	5,258	8,112
Property covered under FDIC loss share agreements	$ 0	$ 106
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)	58,760,517	58,693,304
Common stock, shares outstanding (in shares)	58,760,517	58,693,304

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Interest and dividend income
Loans	$ 101,136	$ 88,192	$ 202,818	$ 175,388
Taxable securities	6,055	5,787	11,933	11,774
Nontaxable securities	241	12	440	24
Dividends on securities	242	222	543	436
Federal funds sold and other	219	94	565	169
Total interest and dividend income	107,893	94,307	216,299	187,791
Interest expense
Deposits	7,829	6,029	15,118	11,694
Securities sold under agreements to repurchase	98	132	212	271
FHLB advances and other borrowings	1,469	929	2,741	1,845
Subordinated debentures and subordinated notes payable	1,098	879	2,186	1,686
Total interest expense	10,494	7,969	20,257	15,496
Net interest income	97,399	86,338	196,042	172,295
Provision for loan and lease losses	4,009	2,631	11,058	6,520
Net interest income after provision for loan and lease losses	93,390	83,707	184,984	165,775
Noninterest income
Service charges and other fees	11,919	10,316	24,005	20,782
Wealth management fees	2,429	1,668	4,683	3,280
Mortgage banking income, net	1,640	1,204	4,302	2,474
Net gain (loss) on sale of securities	44	24	44	(330)
Net increase (decrease) in fair value of loans at fair value	(5,216)	35,955	(69,218)	21,054
Net realized and unrealized gain on derivatives	1,592	(40,893)	60,568	(31,454)
Other	1,426	725	3,357	1,836
Total noninterest income	13,834	8,999	27,741	17,642
Noninterest expense
Salaries and employee benefits	32,370	24,769	64,004	50,065
Data processing	5,965	4,950	11,642	10,196
Occupancy expenses	4,355	3,843	8,380	7,434
Professional fees	3,559	2,652	6,394	5,760
Communication expenses	914	928	1,953	1,862
Advertising	995	1,048	1,970	1,968
Equipment expense	768	931	1,566	1,835
Net loss recognized on repossessed property and other related expenses	397	210	1,056	100
Amortization of core deposits and other intangibles	550	708	1,389	1,417
Acquisition expenses	0	771	710	771
Other	3,979	4,045	7,325	7,667
Total noninterest expense	53,852	44,855	106,389	89,075
Income before income taxes	53,372	47,851	106,336	94,342
Provision for income taxes	18,210	17,177	34,271	33,207
Net income	35,162	30,674	72,065	61,135
Other comprehensive income (loss) - change in net unrealized gain (loss) on securities available for sale (net of deferred income tax (expense) benefit of $(673) and $(6,128) for the three months ended March 31, 2017 and 2016, respectively and $7,485 and $(1,466) for the six months ended March 31, 2017 and 2016, respectively)	1,098	9,998	(12,212)	2,391
Comprehensive income	$ 36,260	$ 40,672	$ 59,853	$ 63,526
Basic earnings per common share
Weighted average shares outstanding (in shares)	58,788,802	55,269,557	58,769,662	55,261,634
Earnings per share (in dollars per share)	$ 0.60	$ 0.56	$ 1.23	$ 1.11
Diluted earnings per common share
Weighted average shares outstanding (in shares)	59,073,669	55,408,876	59,032,787	55,401,164
Diluted earnings per share (in dollars per share)	$ 0.60	$ 0.55	$ 1.22	$ 1.10
Dividends per share
Dividends paid	$ 9,989	$ 7,734	$ 19,970	$ 15,467
Dividends per share (in dollars per share)	$ 0.17	$ 0.14	$ 0.34	$ 0.28

Consolidated Statements of Com5

Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Income tax (expense) benefit	$ (673)	$ (6,128)	$ 7,485	$ (1,466)

Consolidated Statement of Stock

Consolidated Statement of Stockholders' Equity (Unaudited) - 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, 2015	$ 1,459,346		$ 552	$ 1,201,387	$ 255,089	$ 2,318
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	61,135	$ 61,135			61,135
Other comprehensive income, net of tax:
Net change in net unrealized gain (loss) on securities available for sale	2,391	2,391				2,391
Comprehensive income	63,526	63,526
Stock-based compensation, net of tax	1,797			1,797
Common stock cash dividends	(15,467)				(15,467)
Ending balance at Mar. 31, 2016	1,509,202		552	1,203,184	300,757	4,709
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	72,065	72,065			72,065
Other comprehensive income, net of tax:
Net change in net unrealized gain (loss) on securities available for sale	(12,212)	(12,212)				(12,212)
Comprehensive income	59,853	$ 59,853
Stock-based compensation, net of tax	3,587			3,587
Common stock cash dividends	(19,970)				(19,970)
Ending balance at Mar. 31, 2017	$ 1,706,861		$ 587	$ 1,315,934	$ 397,018	$ (6,678)

Consolidated Statement of Stoc7

Consolidated Statement of Stockholders' Equity (Unaudited) (Parenthetical) - $ / shares	6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Stockholders' Equity [Abstract]
Cash dividends paid on common stock (in dollars per share)	$ 0.17	$ 0.14

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating activities
Net income	$ 72,065	$ 61,135
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	9,359	8,260
Amortization of FDIC indemnification asset	1,981	1,927
Net (gain) loss on sale of securities	(44)	330
Gain on redemption of subordinated debentures	(111)	0
Net gain on sale of loans	(5,180)	(2,474)
Net loss on FDIC indemnification asset	643	554
Net gain on sale of premises and equipment	(594)	(34)
Net loss from sale/writedowns of repossessed property	1,056	100
Provision for loan and lease losses	11,058	6,520
Reversal of provision for loan servicing rights loss	(10)	0
Stock-based compensation	3,587	1,797
Originations of residential real estate loans held for sale	(137,061)	(104,655)
Proceeds from sales of residential real estate loans held for sale	150,257	108,604
Deferred income taxes	(328)	1,242
Changes in:
Accrued interest receivable	5,841	4,590
Other assets	1,063	821
FDIC clawback liability	832	473
Accrued interest payable, fair value of derivatives and other liabilities	(78,487)	17,609
Net cash provided by operating activities	35,927	106,799
Investing activities
Purchase of securities available for sale	(183,678)	(128,480)
Proceeds from sales of securities available for sale	5,042	24,996
Proceeds from maturities of securities available for sale	122,760	102,738
Net increase in loans	(36,433)	(236,955)
Payment of covered losses from FDIC indemnification claims	(218)	(634)
Purchase of premises and equipment	(2,830)	(4,825)
Proceeds from sale of premises and equipment	3,868	641
Proceeds from sale of repossessed property	3,453	3,534
Purchase of FHLB stock	(4,240)	(11,815)
Proceeds from redemption of FHLB stock	28,751	20,433
Net cash used in investing activities	(63,525)	(230,367)
Financing activities
Net increase in deposits	487,502	325,664
Net decrease in securities sold under agreements to repurchase	(17,216)	(38,998)
Proceeds from FHLB advances and other borrowings	93,600	75,000
Repayments on FHLB advances and other borrowings	(700,000)	(286,000)
Redemption of subordinated debentures	(5,000)	0
Dividends paid	(19,970)	(15,467)
Net cash (used in) provided by financing activities	(161,084)	60,199
Net decrease in cash and cash equivalents	(188,682)	(63,369)
Cash and cash equivalents, beginning of period	524,611	237,770
Cash and cash equivalents, end of period	335,929	174,401
Supplemental disclosure of cash flow information
Cash payments for interest	20,348	15,515
Cash payments for income taxes	37,350	33,777
Supplemental disclosure of noncash investing and financing activities
Loans transferred to repossessed properties	(1,221)	(786)
Repossessed property transferred to premises and equipment	$ 0	$ (840)

Nature of Operations and Summar

Nature of Operations and Summary of Significant Policies	6 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Nature of Operations and Summary of Significant Policies	Nature of Operations and Summary of Significant Policies Nature of Operations Great Western Bancorp, Inc. (the “Company”) is a bank holding company organized under the laws of Delaware and is listed on the New York Stock Exchange ("NYSE") under the symbol GWB. The primary business of the Company is ownership of its wholly owned subsidiary, Great Western Bank (the “Bank”). The Bank is a full-service regional bank focused on relationship-based business and agri-business banking in Arizona, Colorado, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota and South Dakota . The Company and the Bank are subject to the regulation of certain federal and/or state agencies and undergo periodic examinations by those regulatory authorities. Substantially all of the Company’s income is generated from banking operations. Basis of Presentation The accompanying unaudited consolidated interim financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) and reflect all adjustments that are, in the opinion of management, necessary for the fair presentation of the financial position and results of operations for the periods presented. All such adjustments are of a normal recurring nature. Certain previously reported amounts have been reclassified to conform to the current presentation. The unaudited interim consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements for the year ended September 30, 2016 , which includes a description of significant accounting policies. The results of operations for interim periods are not necessarily indicative of the results that may be expected for the year or any other period. The accompanying unaudited consolidated financial statements include the accounts and results of operations of the Company and its subsidiaries after elimination of all significant intercompany accounts and transactions. The preparation of unaudited consolidated financial statements in conformity with U.S. GAAP requires management to make certain estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from these estimates. Business Combinations The Company accounts for business combinations under the acquisition method of accounting in accordance with ASC 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 in the consolidated statements of comprehensive income from the effective date of acquisition. Use of Estimates U. S. GAAP requires management makes estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. 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 in the consolidated statements of comprehensive 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 (with certain exceptions for debt securities noted below) 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 accumulated other comprehensive income (loss). Interest and dividends, including amortization of premiums and accretion of discounts, are recognized as interest or dividend 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 in the consolidated statements of comprehensive income. 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, generally 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. Accrual of interest is discontinued when management believes, after considering collection efforts and other factors, the borrower’s financial condition is such that collection of interest is doubtful, which is generally at 90 days past due. Generally, when loans are placed on nonaccrual status, 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 agribusiness 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 grants commercial, agricultural, consumer, residential real estate, 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, inventory, property and equipment, residential real estate, and income-producing commercial and agricultural properties. 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, 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 residential real estate, commercial real estate, commercial non real estate, agriculture, consumer and other lending. 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 commercial real estate lending class includes loans made to small and middle market businesses, including multifamily properties. Loans in this class are 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, and nature of pledged collateral. We consider 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 our 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, and nature of pledged collateral. We consider 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 guaranteed by owners; cashflows are most often our 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, and nature of pledged collateral. We consider these risk characteristics in assigning risk ratings and estimating 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 for 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 on a continuous basis. The Company generally does not risk rate 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 (“TDRs”) 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. Our TDRs include performing and nonperforming TDRs, which consist of loans that continue to accrue interest at the loan's original interest rate as we expect 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 we do 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 we move the loan to a performing status (performing TDR). If we do 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 our 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 (“ALLL”) and Unfunded Commitments The Company maintains an allowance for loan and lease losses at a level management believes is appropriate to reserve for credit losses inherent in our 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 is 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 in the consolidated statements of comprehensive income. Past due status is monitored as an indicator of credit deterioration. Loans that are 90 days or more past due are put on nonaccrual status unless the loan is well secured and in the process of collection. 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 our 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 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. 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 recognized. For acquired nonimpaired 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 nonimpaired 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. We maintain a reserve for unfunded commitments at a level we believe to be sufficient to absorb estimated probable losses related to unfunded credit facilities. FDIC Indemnification Asset and Clawback Liability In conjunction with a Federal Deposit Insurance Corporation (“FDIC”) assisted transaction of TierOne Bank in 2010, the Company entered into two loss share agreements with the FDIC, one covering certain single family residential mortgage loans with the claim period ending June 2020 and one covering commercial loans and other assets, in which the claim period ended in June 2015. The agreements cover a portion of realized losses on loans, foreclosed real estate and certain other assets. The Company has recorded assets on the consolidated balance sheets (i.e. indemnification assets) representing estimated future amounts recoverable from the FDIC. Fair values of loans covered by the loss sharing agreements 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 agreements. 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 comprehensive income. Although these assets are contractual receivables from the FDIC, there are no contractual interest rates. As part of the loss sharing agreements, 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 agreements that is contingent upon actual losses incurred over the life of the agreements 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 agreements. 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 agreements 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. Goodwill Goodwill represents the cost in excess of the fair value of net assets acquired (including identifiable intangibles) in transactions accounted for as business acquisitions. Goodwill is evaluated annually for impairment. The Company performs its impairment evaluation as of June 30 of each fiscal year. If the implied fair value of goodwill is lower than its carrying amount, goodwill impairment is indicated and goodwill is written down to its implied fair value. Subsequent increases in goodwill are not recognized in the consolidated financial statements. No goodwill impairment was recognized during the three and six months ended March 31, 2017 and 2016 . 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 purchase acquisitions. Brand intangible represents the value associated with the Bank charter . Customer relationships intangible represents the identifiable intangible value assigned to customer rela

New Accounting Pronouncements

New Accounting Pronouncements	6 Months Ended
	Mar. 31, 2017
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements In March 2017, the Financial Accounting Standards Board (FASB) issued ASU 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities, which shortens the amortization period for certain callable debt securities held at a premium to the earliest call date. There is no accounting change for debt securities held at a discount. ASU 2017-08 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. The Company is currently evaluating the potential impact of ASU 2017-08 on our consolidated financial statements. In March 2017, the FASB issued ASU 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, which requires an employer to report the service cost component in the same line item as other compensation costs arising from services rendered by employees in the income statement with the other components of the net benefit cost presented below the income from operations line in the income statement. ASU 2017-07 will be effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017, with early adoption permitted as of the beginning of the annual period. The Company is currently evaluating the potential impact of ASU 2017-07 on our consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, which eliminates Step 2 from the goodwill impairment test. Under this ASU, an entity should perform its annual or interim goodwill impairment test by comparing the fair value of the reporting unit with its carrying amount, and should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value with the loss not exceeding the total amount of goodwill allocated to that reporting unit. ASU 2017-04 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. The Company is currently evaluating the potential impact of ASU 2017-04 on our consolidated financial statements. In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying 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. The amendment provides a screen to determine when an integrated set of assets and activities (a "set") is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. The amendment also provides a more robust framework to use in determining when a set of assets and activities is a business. ASU 2017-01 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. The Company is currently evaluating the potential impact of ASU 2017-01 on our 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 alters how a decision maker needs to consider indirect interests in a variable interest entity held through an entity under common control and simplifies that analysis to require consideration of only an entity’s proportionate indirect interest in a VIE held through a common control party. ASU 2016-17 amends ASU 2015-02, Consolidations (Topic 810): Amendments to the Consolidation Analysis , which was not effective for the Company in the current fiscal year. ASU 2016-17 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. The Company is currently evaluating the potential impact of ASU 2016-17 on our 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 addresses improvement in accounting for income tax consequences of intra-equity transfers of assets other than inventory. This update requires 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 eliminates the exception for an intra-equity transfer for assets other than inventory. ASU 2016-16 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. The amendment requires the use of a modified retrospective transaction approach through a cumulative effect adjustment directly to retained earnings as of the beginning of adoption. The Company is currently evaluating the potential impact of ASU 2016-16 on our 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 addresses 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. ASU 2016-15 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. The amendment requires the use of the retrospective transaction approach for adoption. The Company is currently evaluating the potential impact of ASU 2016-15 on our consolidated financial statements. In June 2016, the FASB issued ASU No. 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. The ASU 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 ("CECL") model. The ASU 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. ASU 2016-13 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 amendment requires the use of the modified retrospective approach for adoption. ASU 2016-13 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 amendment requires the use of the modified retrospective approach for adoption. The Company is currently evaluating the potential impact of ASU 2016-13 on our consolidated financial statements. In March 2016, the FASB issued ASU No. 2016-09, Compensation - Stock Based Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting , which addresses several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU 2016-09 is effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2016. Earlier application is permitted. If an entity early adopts the amendments in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period. An entity that elects early adoption must adopt all of the amendments in the same period. The Company is currently evaluating the potential impact of ASU 2016-09 on our consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02 , Leases (Topic 842) , which requires that lessees recognize most leases on the balance sheet. This will increase reported assets and liabilities, as lessees will be required to recognize a right-of-use asset along with a lease liability, measured on a discounted basis. Lessees are allowed to account for short-term leases (those with a term of twelve months or less) off-balance sheet. ASU 2016-02 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The Company is currently evaluating the potential impact of ASU 2016-02 on our consolidated financial statements. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10) - Recognition and Measurement of Financial Assets and Financial Liabilities, which addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments. ASU 2016-01 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. The Company is currently evaluating the potential impact of ASU 2016-01 on our consolidated financial statements. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) , which implements a common revenue standard that clarifies the principles for recognizing revenue. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. In August 2015, the FASB issued ASU No. 2015-14 which deferred the effective date of ASU No. 2014-09 to annual reporting periods beginning after December 15, 2017. In March 2016, the FASB issued ASU No. 2016-08, which intends to improve the operability and understandability of the implementation guidance on principal versus agent considerations. In April 2016, the FASB issued ASU No. 2016-10, which clarifies guidance pertaining to the identification of performance obligations and the licensing implementation. In May 2016, the FASB issued ASU Nos. 2016-11 and 2016-12, which further clarify guidance and provide practical expedients related to the adoption of ASU No. 2014-09. In December 2016, the FASB issued ASU 2016-19, Technical Corrections and Improvements to Topic 606, which provides additional clarification and improvements for the following areas: loan guarantee fees, contract costs-impairment testing, provision for losses on construction-type and production-type contracts, cost capitalization guidance, and disclosure requirements. The standard permits the use of either the retrospective or cumulative effect transition method. In March 2017, the FASB issued ASU No. 2017-05, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets, which provides guidance for recognizing gains and losses from the transfer of nonfinancial assets in contracts with noncustomers. The Company is currently evaluating the potential impact of these standards on our consolidated financial statements.

Acquisition Activity

Acquisition Activity	6 Months Ended
	Mar. 31, 2017
Business Combinations [Abstract]
Acquisition Activity	Acquisition Activity On May 16, 2016, the Company acquired by merger 100% of HF Financial, the holding company of Home Federal Bank. Under terms of the agreement, HF Financial's stockholders had the right to receive for each share of HF Financial common stock, at their election (but subject to proration in the event cash or stock is oversubscribed), either (i) 0.6500 share of the Company's common stock, or (ii) $19.50 in cash. The total consideration was prorated as necessary to ensure that 24.29% of the total outstanding shares of HF Financial common stock were exchanged for cash and 75.71% of the total outstanding shares of HF Financial common stock were exchanged for shares of the Company's common stock. Total merger consideration of $142.0 million was paid by the Company in the acquisition, which resulted in goodwill of $41.2 million , as shown in the table below. With this acquisition, the Company expanded its presence in South Dakota and into North Dakota and Minnesota through the addition of 23 bank offices and experienced in-market teams. The following summarizes consideration paid and an allocation of purchase price to net assets acquired. Number of Shares Amount (dollars in thousands) Equity consideration: Common stock issued 3,448,119 $ 107,478 Non-equity consideration: Cash 34,487 Total consideration paid 141,965 Fair value of net assets acquired including identifiable intangible assets 100,749 Goodwill $ 41,216 As of the acquisition date, goodwill of $41.2 million arose from the acquisition as a result of consideration in excess of net assets acquired. No goodwill is expected to be deductible for income tax purposes. The fair value of intangible assets created in the acquisition was $14.5 million related to core deposits and other intangible assets and loan servicing rights. During the fourth quarter of 2016, the Company obtained additional information regarding the valuation of the deferred tax assets, which resulted in an increase in goodwill recognized in the transaction of $0.6 million . There were no adjustments to current period income statement as a result of the adjustment. The following table summarizes the assets acquired and liabilities assumed which were recorded on the consolidated balance sheet as of the date of merger of HF Financial: Fair Value (dollars in thousands) Identifiable assets acquired: Cash and cash equivalents $ 18,818 Investment securities 165,052 Loans 863,741 Premises and equipment 19,220 Accrued interest receivable 4,117 Other repossessed property 4 Intangible assets 7,877 Loan servicing rights 6,573 Other assets 36,076 Total identifiable assets acquired $ 1,121,478 Liabilities assumed: Deposits $ 863,121 FHLB advances and other borrowings 115,881 Subordinated debentures 21,110 Other liabilities 20,617 Total liabilities assumed 1,020,729 Fair value of net identifiable assets acquired 100,749 Net purchase price 141,965 Goodwill $ 41,216 The Company accounted for the aforementioned business combination under the acquisition method in accordance with ASC Topic 805, Business Combinations . Accordingly, the purchase price is allocated to the fair value of the assets acquired and liabilities assumed as of the date of acquisition. The foregoing purchase price allocations on the acquisition are preliminary and will be finalized upon the receipt of final valuations on certain assets and liabilities. Upon receipt of final fair value estimates, which must be within one year of the acquisition date, the Company will make any final adjustments to the purchase price allocation and retrospectively adjust any goodwill recorded. Material adjustments to acquisition date estimated fair values would be recorded in the reporting period in which the adjustment amounts are determined. Determining the fair value of assets and liabilities, particularly illiquid assets and liabilities, is a complicated process involving significant judgment regarding estimates and assumptions used to calculate estimated fair value. Fair value adjustments based on updated estimates could materially affect the goodwill recorded on the acquisition. The Company may incur losses on the acquired loans that are materially different from losses the Company originally projected. The results of the merged HF Financial operations are presented within the Company’s consolidated financial statements from the acquisition date. The disclosure of HF Financial's post-acquisition revenue and net income is not practical due to the combining of HF Financial’s operations with and into the Company as of the acquisition date. Acquisition-related transaction expenses associated with the HF Financial acquisition totaled $0.0 million and $0.8 million for the three months ended March 31, 2017 and 2016 , respectively, and $0.7 million and $0.8 million for the six months ended March 31, 2017 and 2016 , respectively. Supplemental pro forma information (unaudited) The following unaudited pro forma combined results of operations of the Company and HF Financial presents results as if the acquisition had been completed as of the beginning of each period indicated. The unaudited pro forma combined results of operations are presented solely for information purposes and are not intended to represent or be indicative of the consolidated results of operations that the Company would have reported had this transaction been completed as of the dates and for the periods presented, nor are they necessarily indicative of future results. In particular, no adjustments have been made to eliminate the amount of HF Financial's provision for loan and lease losses incurred prior to the acquisition date that would not have been necessary had the acquired loans been recorded at fair value as of the beginning of each period indicated. In accordance with Article 11 of SEC Regulation S-X, transaction costs directly attributable to the acquisition have been excluded. Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (Unaudited, dollars in thousands, except per share data) Net interest income $ 97,399 $ 95,940 $ 196,042 $ 191,383 Net income 35,162 32,743 72,065 64,682 Basic earnings per share 0.60 0.59 1.23 1.17 Fully diluted earnings per share 0.60 0.59 1.22 1.17 In the acquisition, the Company acquired $863.7 million of loans at fair value, net of $28.5 million , or 3.30% , estimated discount to the outstanding principal balance. Of the total loans acquired, management identified $65.4 million that were considered to be credit impaired and are accounted for under ASC Topic 310-30. The table below summarizes the total contractually required principal and interest cash payments, management's estimate of expected total cash payments and fair value of the loans as of acquisition date for purchased credit impaired loans. Contractually required principal and interest payments have been adjusted for estimated prepayments. Amount (Unaudited, dollars in thousands) Contractually required principal and interest $ 83,710 Non-accretable difference (28,516 ) Cash flows expected to be collected 55,194 Accretable yield (3,662 ) Total purchased credit impaired loans acquired $ 51,532 The following table presents the acquired loan data for the HF Financial acquisition. Fair Value of Acquired Loans at Acquisition Date Gross Contractual Amounts Receivable at Acquisition Date Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected (Unaudited, dollars in thousands) Acquired receivables subject to ASC 310-30 $ 51,532 $ 83,710 $ 28,516 Acquired receivables not subject to ASC 310-30 812,209 998,255 9,572

Securities Available for Sale

Securities Available for Sale	6 Months Ended
	Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Securities Available for Sale	Securities Available for Sale The amortized cost and approximate fair value of investments in securities, all of which are classified as available for sale according to management’s intent, are summarized as follows: Amortized Gross Unrealized Gains Gross Unrealized Losses Estimated (dollars in thousands) As of March 31, 2017 U.S. Treasury securities $ 227,521 $ 1,195 $ (6 ) $ 228,710 Mortgage-backed securities: Government National Mortgage Association 592,330 419 (7,654 ) 585,095 Federal National Mortgage Association 271,184 40 (2,356 ) 268,868 Small Business Assistance Program 198,313 342 (1,525 ) 197,130 States and political subdivision securities 71,288 81 (1,308 ) 70,061 Corporate debt securities — — — — Other 1,013 16 — 1,029 Total $ 1,361,649 $ 2,093 $ (12,849 ) $ 1,350,893 Amortized Gross Unrealized Gains Gross Unrealized Losses Estimated (dollars in thousands) As of September 30, 2016 U.S. Treasury securities $ 227,007 $ 3,973 $ — $ 230,980 Mortgage-backed securities: Government National Mortgage Association 664,529 3,172 (1,922 ) 665,779 Federal National Mortgage Association 212,452 1,324 — 213,776 Small Business Assistance Program 142,921 2,362 — 145,283 States and political subdivision securities 55,525 123 (164 ) 55,484 Corporate debt securities 4,998 24 — 5,022 Other 1,013 49 — 1,062 Total $ 1,308,445 $ 11,027 $ (2,086 ) $ 1,317,386 The amortized cost and approximate fair value of debt securities available for sale as of March 31, 2017 and September 30, 2016 , by contractual maturity, are shown below. Maturities of mortgage-backed securities may differ from contractual maturities because the mortgages underlying the securities may be called or repaid without penalty. March 31, 2017 September 30, 2016 Amortized Estimated Amortized Estimated (dollars in thousands) Due in one year or less $ 30,263 $ 30,307 $ 3,706 $ 3,709 Due after one year through five years 248,718 249,230 265,253 269,242 Due after five years through ten years 19,706 19,112 18,449 18,413 Due after ten years 122 122 122 122 298,809 298,771 287,530 291,486 Mortgage-backed securities 1,061,827 1,051,093 1,019,902 1,024,838 Securities without contractual maturities 1,013 1,029 1,013 1,062 Total $ 1,361,649 $ 1,350,893 $ 1,308,445 $ 1,317,386 Proceeds from sales of securities available for sale were $5.0 million and $25.0 million for the three and six months ended March 31, 2017 and 2016 , respectively. Gross gains (pre-tax) of $0.0 million and gross losses (pre-tax) of $0.0 million a were realized on the sales for the three and six months ended March 31, 2017 and 2016 , respectively, using the specific identification method. The Company recognized no other-than-temporary impairment for the three months ended March 31, 2017 and 2016 . The Company recognized no other-than-temporary impairment for the six months ended March 31, 2017 and $0.4 million for the six months ended March 31, 2016 in net loss on sale of securities in the consolidated statements of comprehensive income on two security holdings attributable to credit. Securities with an estimated fair value of approximately $836.5 million and $971.3 million at March 31, 2017 and September 30, 2016 , 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 70% and 25% of the Company’s investment portfolio at March 31, 2017 and September 30, 2016 , 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 March 31, 2017 or September 30, 2016 . The following table presents the Company’s gross unrealized losses and approximate fair value in investments, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position: Less than 12 months 12 months or more Total Estimated Unrealized Estimated Unrealized Estimated Unrealized (dollars in thousands) As of March 31, 2017 U.S. Treasury securities $ 19,539 $ (6 ) $ — $ — $ 19,539 $ (6 ) Mortgage-backed securities 602,146 (6,030 ) 276,282 (5,505 ) 878,428 (11,535 ) States and political subdivision securities 53,052 (1,308 ) — — 53,052 (1,308 ) Total $ 674,737 $ (7,344 ) $ 276,282 $ (5,505 ) $ 951,019 $ (12,849 ) Less than 12 months 12 months or more Total Estimated Unrealized Estimated Unrealized Estimated Unrealized (dollars in thousands) As of September 30, 2016 U.S. Treasury securities $ — $ — $ — $ — $ — $ — Mortgage-backed securities $ 17,528 $ (6 ) $ 284,995 $ (1,916 ) $ 302,523 $ (1,922 ) States and political subdivision securities 27,933 (164 ) — — 27,933 (164 ) Total $ 45,461 $ (170 ) $ 284,995 $ (1,916 ) $ 330,456 $ (2,086 ) As of March 31, 2017 and September 30, 2016 , the Company had 260 and 110 securities, respectively, in an unrealized loss position. The components of accumulated other comprehensive income (loss) from net unrealized gains (losses) on securities available for sale for the three and six months ended March 31, 2017 and 2016 , are as follows: Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands) Beginning balance accumulated other comprehensive income (loss) $ (7,776 ) $ (5,289 ) $ 5,534 $ 2,318 Net unrealized holding gain (loss) arising during the period 1,727 16,102 (19,741 ) 4,187 Reclassification adjustment for net gain (loss) realized in net income 44 24 44 (330 ) Net change in unrealized gain (loss) before income taxes 1,771 16,126 (19,697 ) 3,857 Income tax (expense) benefit (673 ) (6,128 ) 7,485 (1,466 ) Net change in unrealized gain (loss) on securities after taxes 1,098 9,998 (12,212 ) 2,391 Ending balance accumulated other comprehensive income (loss) $ (6,678 ) $ 4,709 $ (6,678 ) $ 4,709

Loans

Loans	6 Months Ended
	Mar. 31, 2017
Receivables [Abstract]
Loans	Loans The composition of loans as of March 31, 2017 and September 30, 2016 , is as follows: March 31, 2017 September 30, 2016 (dollars in thousands) Residential real estate $ 971,374 $ 1,020,958 Commercial real estate 3,850,835 3,754,107 Commercial non real estate 1,690,149 1,673,166 Agriculture 2,114,287 2,168,937 Consumer 74,718 76,273 Other 39,976 42,477 Ending balance 8,741,339 8,735,918 Less: Unamortized discount on acquired loans (34,812 ) (39,947 ) Unearned net deferred fees and costs and loans in process (9,101 ) (13,327 ) Total $ 8,697,426 $ 8,682,644 The loan breakouts above include loans covered by FDIC loss sharing agreements totaling $64.7 million and $73.3 million as of March 31, 2017 and September 30, 2016 , respectively, residential real estate loans held for sale totaling $4.9 million and $12.9 million at March 31, 2017 and September 30, 2016 , respectively, and $1.06 billion and $1.13 billion of loans and written loan commitments accounted for at fair value at March 31, 2017 and September 30, 2016 , respectively. Unearned net deferred fees and costs totaled $9.2 million and $8.6 million as of March 31, 2017 and September 30, 2016 , respectively. Loans in process represent loans that have been funded as of the balance sheet dates but not classified into a loan category and loan payments received as of the balance sheet dates that have not been applied to individual loan accounts. Loans in process totaled $(0.1) million and $4.7 million at March 31, 2017 and September 30, 2016 , respectively. Loans guaranteed by agencies of the U.S. government totaled $160.8 million and $120.0 million at March 31, 2017 and September 30, 2016 , respectively. Principal balances of residential real estate loans sold totaled $53.4 million and $50.4 million for the three months ended March 31, 2017 and 2016 , respectively and $145.1 million and $108.6 million for the six months ended March 31, 2017 and 2016 , respectively. Nonaccrual The following table presents the Company’s nonaccrual loans at March 31, 2017 and September 30, 2016 , excluding ASC 310-30 loans. Loans greater than 90 days past due and still accruing interest as of March 31, 2017 and September 30, 2016 , were $3.8 million and $2.0 million , respectively. March 31, 2017 September 30, 2016 Nonaccrual loans (dollars in thousands) Residential real estate $ 5,290 $ 5,962 Commercial real estate 13,165 13,870 Commercial non real estate 27,273 27,280 Agriculture 70,134 66,301 Consumer 193 223 Total $ 116,055 $ 113,636 Credit Quality Information The composition of the loan portfolio by internally assigned grade is as follows as of March 31, 2017 and September 30, 2016 . 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 $1.06 billion at March 31, 2017 and $1.13 billion at September 30, 2016 : As of March 31, 2017 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total Credit Risk Profile by Internally Assigned Grade (dollars in thousands) Grade: Pass $ 881,321 $ 3,433,051 $ 1,115,087 $ 1,447,894 $ 73,646 $ 39,976 $ 6,990,975 Watchlist 3,962 68,585 36,378 215,434 98 — 324,457 Substandard 9,520 44,298 35,687 173,766 445 — 263,716 Doubtful 357 519 5,459 206 — — 6,541 Ending balance 895,160 3,546,453 1,192,611 1,837,300 74,189 39,976 7,585,689 Loans covered by FDIC loss sharing agreements 64,681 — — — — — 64,681 Total $ 959,841 $ 3,546,453 $ 1,192,611 $ 1,837,300 $ 74,189 $ 39,976 $ 7,650,370 As of September 30, 2016 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total Credit Risk Profile by Internally Assigned Grade (dollars in thousands) Grade: Pass $ 919,224 $ 3,276,048 $ 1,093,913 $ 1,514,344 $ 75,065 $ 42,477 $ 6,921,071 Watchlist 4,741 81,148 37,283 204,326 110 — 327,608 Substandard 10,885 57,415 42,319 130,569 417 — 241,605 Doubtful 130 147 395 630 — — 1,302 Ending balance 934,980 3,414,758 1,173,910 1,849,869 75,592 42,477 7,491,586 Loans covered by FDIC loss sharing agreements 73,272 — — — — — 73,272 Total $ 1,008,252 $ 3,414,758 $ 1,173,910 $ 1,849,869 $ 75,592 $ 42,477 $ 7,564,858 Past Due Loans The following table presents the Company’s past due loans at March 31, 2017 and September 30, 2016 . 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 $1.06 billion at March 31, 2017 and $1.13 billion at September 30, 2016 . 30-59 Days Past Due 60-89 Days Past Due 90 Days or Greater Past Due Total Current Total Financing Receivables As of March 31, 2017 (dollars in thousands) Residential real estate $ 2,943 $ 869 $ 1,704 $ 5,516 $ 889,644 $ 895,160 Commercial real estate 386 — 4,909 5,295 3,541,158 3,546,453 Commercial non real estate 2,118 670 16,422 19,210 1,173,401 1,192,611 Agriculture 9,408 2,822 10,998 23,228 1,814,072 1,837,300 Consumer 71 3 42 116 74,073 74,189 Other — — — — 39,976 39,976 Ending balance 14,926 4,364 34,075 53,365 7,532,324 7,585,689 Loans covered by FDIC loss sharing agreements 1,430 642 578 2,650 62,031 64,681 Total $ 16,356 $ 5,006 $ 34,653 $ 56,015 $ 7,594,355 $ 7,650,370 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, 2016 (dollars in thousands) Residential real estate $ 828 $ 548 $ 2,063 $ 3,439 $ 931,541 $ 934,980 Commercial real estate 1,765 1,959 3,745 7,469 3,407,289 3,414,758 Commercial non real estate 1,588 5,515 9,594 16,697 1,157,213 1,173,910 Agriculture (26 ) 709 11,549 12,232 1,837,637 1,849,869 Consumer 209 20 28 257 75,335 75,592 Other — — — — 42,477 42,477 Ending balance 4,364 8,751 26,979 40,094 7,451,492 7,491,586 Loans covered by FDIC loss sharing agreements 1,404 1,173 367 2,944 70,328 73,272 Total $ 5,768 $ 9,924 $ 27,346 $ 43,038 $ 7,521,820 $ 7,564,858 Impaired Loans The following table presents the Company’s impaired loans. This table excludes loans covered by FDIC loss sharing agreements: March 31, 2017 September 30, 2016 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance Related Allowance Impaired loans: (dollars in thousands) With an allowance recorded: Residential real estate $ 6,243 $ 6,916 $ 3,288 $ 6,244 $ 6,886 $ 3,000 Commercial real estate 25,935 30,199 3,601 29,965 32,349 3,846 Commercial non real estate 27,195 28,537 4,985 34,526 35,283 6,475 Agriculture 83,940 95,814 10,616 71,501 80,842 12,278 Consumer 421 433 103 383 393 87 Total impaired loans with an allowance recorded 143,734 161,899 22,593 142,619 155,753 25,686 With no allowance recorded: Residential real estate 3,140 4,830 — 4,120 5,807 — Commercial real estate 13,639 14,295 — 24,040 24,660 — Commercial non real estate 17,837 22,317 — 15,299 16,469 — Agriculture 61,293 63,326 — 30,339 31,907 — Consumer 5 5 — 12 12 — Total impaired loans with no allowance recorded 95,914 104,773 — 73,810 78,855 — Total impaired loans $ 239,648 $ 266,672 $ 22,593 $ 216,429 $ 234,608 $ 25,686 The average recorded investment on impaired loans and interest income recognized on impaired loans for the three and six months ended March 31, 2017 and 2016 , respectively, are as follows: Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status (dollars in thousands) Residential real estate $ 9,565 $ 126 $ 12,124 $ 290 $ 9,831 $ 240 $ 12,204 $ 439 Commercial real estate 44,807 545 83,642 2,004 47,873 1,215 78,345 3,473 Commercial non real estate 46,304 358 40,450 766 47,477 780 48,798 1,122 Agriculture 128,919 1,326 109,473 3,256 119,892 3,193 91,013 5,695 Consumer 389 12 308 25 391 27 282 42 Total $ 229,984 $ 2,367 $ 245,997 $ 6,341 $ 225,464 $ 5,455 $ 230,642 $ 10,771 Valuation adjustments made to repossessed properties totaled $0.5 million for the three months ended March 31, 2017 and 2016 and $0.9 million and $0.5 million for the six months ended March 31, 2017 and 2016 , respectively. The adjustments are included in noninterest expense. Troubled Debt Restructurings Included in certain loan categories in the impaired loans are troubled debt restructurings (“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 $7.2 million and $9.3 million at March 31, 2017 and September 30, 2016 , respectively. Commitments to lend additional funds to borrowers whose loans were modified in a TDR were $0.0 million and $0.9 million as of March 31, 2017 and September 30, 2016 , respectively. The following table presents the recorded value of the Company’s TDR balances as of March 31, 2017 and September 30, 2016 : March 31, 2017 September 30, 2016 Accruing Nonaccrual Accruing Nonaccrual (dollars in thousands) Residential real estate $ 328 $ 614 $ 370 $ 937 Commercial real estate 5,302 2,178 18,250 2,356 Commercial non real estate 4,859 2,033 8,102 4,789 Agriculture 28,162 38,674 19,823 28,688 Consumer 4 29 23 8 Total $ 38,655 $ 43,528 $ 46,568 $ 36,778 The following table presents a summary of all accruing loans restructured in TDRs during the three months ended March 31, 2017 and 2016 , respectively: Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Residential real estate Rate modification — $ — $ — — $ — $ — Term extension — — — — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total residential real estate — — — — — — Commercial real estate Rate modification — — — — — — Term extension — — — — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — 3 6,714 6,714 Total commercial real estate — — — 3 6,714 6,714 Commercial non real estate Rate modification — — — 1 49 49 Term extension — — — — — — Payment modification 2 93 93 1 70 70 Bankruptcy — — — — — — Other — — — 3 3,849 3,849 Total commercial non real estate 2 93 93 5 3,968 3,968 Agriculture Rate modification — — — — — — Term extension 2 8,434 8,434 5 4,941 4,941 Payment modification — — — 4 989 989 Bankruptcy — — — — — — Other — — — — — — Total agriculture 2 8,434 8,434 9 5,930 5,930 Consumer Rate modification — — — — — — Term extension — — — — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total consumer — — — — — — Total accruing 4 $ 8,527 $ 8,527 17 $ 16,612 $ 16,612 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 accruing loans restructured in TDRs during the six months ended March 31, 2017 and 2016 , respectively: Six Months Ended March 31, 2017 Six Months Ended March 31, 2016 Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Residential real estate Rate modification — $ — $ — — $ — $ — Term extension — — — — — — Payment modification 1 9 9 — — — Bankruptcy — — — — — — Other — — — — — — Total residential real estate 1 9 9 — — — Commercial real estate Rate modification — — — — — — Term extension — — — 2 1,898 1,898 Payment modification — — — — — — Bankruptcy — — — — — — Other — — — 3 6,714 6,714 Total commercial real estate — — — 5 8,612 8,612 Commercial non real estate Rate modification — — — 1 49 49 Term extension — — — 1 58 58 Payment modification 4 526 526 1 70 70 Bankruptcy — — — — — — Other — — — 3 3,849 3,849 Total commercial non real estate 4 526 526 6 4,026 4,026 Agriculture Rate modification — — — — — — Term extension 2 8,434 8,434 13 26,914 26,914 Payment modification — — — 4 989 989 Bankruptcy — — — — — — Other — — — — — — Total agriculture 2 8,434 8,434 17 27,903 27,903 Consumer Rate modification — — — — — — Term extension — — — — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total consumer — — — — — — Total accruing 7 $ 8,969 $ 8,969 28 $ 40,541 $ 40,541 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 non-accruing loans restructured in TDRs during the three months ended March 31, 2017 and 2016 : Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Residential real estate Rate modification — $ — $ — — $ — $ — Term extension — — — — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total residential real estate — — — — — — Commercial real estate Rate modification — — — — — — Term extension — — — — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total commercial real estate — — — — — — Commercial Non Real Estate Rate modification — — — — — — Term extension — — — — — — Payment modification — — — 1 364 364 Bankruptcy — — — — — — Other — — — — — — Total commercial non real estate — — — 1 364 364 Agriculture Rate modification — — — — — — Term extension 6 12,988 12,988 — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total agriculture 6 12,988 12,988 — — — Consumer Rate modification — — — — — — Term extension 3 21 21 — — — Payment modification — — — — — — Bankruptcy — — — 1 8 8 Other — — — — — — Total consumer 3 21 21 1 8 8 Total non-accruing 9 $ 13,009 $ 13,009 2 $ 372 $ 372 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 non-accruing loans restructured in TDRs during the six months ended March 31, 2017 and 2016 : Six Months Ended March 31, 2017 Six Months Ended March 31, 2016 Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Residential real estate Rate modification — $ — $ — — $ — $ — Term extension — — — — — — Payment modification 1 21 21 1 187 187 Bankruptcy — — — — — — Other — — — — — — Total residential real estate 1 21 21 1 187 187 Commercial real estate Rate modification — — — — — — Term extension — — — — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total commercial real estate — — — — — — Commercial Non Real Estate Rate modification — — — — — — Term extension — — — — — — Payment modification — — — 2 760 760 Bankruptcy — — — — — — Other — — — — — — Total commercial non real estate — — — 2 760 760 Agriculture Rate modification — — — — — — Term extension 6 12,988 12,988 — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total agriculture 6 12,988 12,988 — — — Consumer Rate modification — — — — — — Term extension 3 21 21 — — — Payment modification — — — — — — Bankruptcy — — — 1 8 8 Other — — — — — — Total consumer 3 21 21 1 8 8 Total non-accruing 10 $ 13,030 $ 13,030 4 $ 955 $ 955 Change in recorded investment due to principal paydown at time of modification — $ — $ — — $ — $ — Change in recorded investment due to chargeoffs at time of modification — $ — $ — — $ — $ — The table below represents loans that were modified as TDRs within the previous 12 months and for which there was a payment default for the three and six months ended March 31, 2017 and 2016 , respectively. Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 Number of Loans Recorded Investment Number of Loans Recorded Investment Number of Loans Recorded Investment Number of Loans Recorded Investment (dollars in thousands) Residential real estate — $ — 1 $ — — $ — 1 $ — Commercial real estate — — — — 1 34 — — Commercial non real estate 1 — — — 1 — 1 364 Agriculture — — 2 — — — 2 — Consumer — — — — — — 1 8 Total 1 $ — 3 $ — 2 $ 34 5 $ 372 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 above 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. For the three months ended March 31, 2017 and 2016 , there were $2.1 million and $0.0 million , respectively, and $2.1 million and $4.3 million for the six months ended March 31, 2017 and 2016 , respectively, of loans removed from TDR status as they were restructured at market terms and are performing.

Allowance for Loan and Lease Lo

Allowance for Loan and Lease Losses	6 Months Ended
	Mar. 31, 2017
Receivables [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 three and six months ended March 31, 2017 and 2016 : Three Months Ended March 31, 2017 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total (dollars in thousands) Beginning balance January 1, 2017 $ 6,786 $ 16,623 $ 13,443 $ 28,519 $ 340 $ 1,056 $ 66,767 Charge-offs (117 ) (1,824 ) (1,734 ) (4,554 ) (31 ) (819 ) (9,079 ) Recoveries 56 286 121 118 15 392 988 Provision 210 2,096 119 2,237 47 351 5,060 Improvement of ASC 310-30 loans (866 ) (185 ) — — — — (1,051 ) Ending balance March 31, 2017 $ 6,069 $ 16,996 $ 11,949 $ 26,320 $ 371 $ 980 $ 62,685 Three Months Ended March 31, 2016 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total (dollars in thousands) Beginning balance January 1, 2016 $ 7,798 $ 19,405 $ 17,160 $ 15,473 $ 341 $ 951 $ 61,128 Charge-offs (506 ) (744 ) (212 ) (1,113 ) (98 ) (597 ) (3,270 ) Recoveries 295 409 235 77 45 367 1,428 Provision 1,218 1,893 (4,552 ) 3,886 48 206 2,699 Improvement of ASC 310-30 loans (9 ) (59 ) — — — — (68 ) Ending balance March 31, 2016 $ 8,796 $ 20,904 $ 12,631 $ 18,323 $ 336 $ 927 $ 61,917 Six Months Ended March 31, 2017 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total (dollars in thousands) Beginning balance October 1, 2016 $ 7,106 $ 17,946 $ 12,990 $ 25,115 $ 438 $ 1,047 $ 64,642 Charge-offs (267 ) (1,824 ) (3,693 ) (7,420 ) (110 ) (1,317 ) (14,631 ) Recoveries 262 385 219 144 30 576 1,616 Provision (140 ) 549 2,433 8,481 13 674 12,010 Improvement of ASC 310-30 loans (892 ) (60 ) — — — — (952 ) Ending balance March 31, 2017 $ 6,069 $ 16,996 $ 11,949 $ 26,320 $ 371 $ 980 $ 62,685 Six Months Ended March 31, 2016 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total (dollars in thousands) Beginning balance October 1, 2015 $ 8,025 $ 18,014 $ 15,996 $ 13,952 $ 348 $ 865 $ 57,200 Charge-offs (702 ) (772 ) (257 ) (1,124 ) (146 ) (997 ) (3,998 ) Recoveries 339 491 639 124 70 532 2,195 Provision 1,240 3,260 (3,677 ) 5,371 64 527 6,785 Improvement of ASC 310-30 loans (106 ) (89 ) (70 ) — — — (265 ) Ending balance March 31, 2016 $ 8,796 $ 20,904 $ 12,631 $ 18,323 $ 336 $ 927 $ 61,917 The following tables provide details regarding the allowance for loan and lease losses and balance by type of allowance as of March 31, 2017 and September 30, 2016 . These tables are presented net of unamortized discount on acquired loans and excludes loans of $1.06 billion measured at fair value, loans held for sale of $4.9 million , and guaranteed loans of $160.8 million for March 31, 2017 and loans measured at fair value of $1.13 billion , loans held for sale of $12.9 million , and guaranteed loans of $120.0 million for September 30, 2016 . As of March 31, 2017 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total (dollars in thousands) Allowance for loan and lease losses Individually evaluated for impairment $ 3,288 $ 3,601 $ 4,985 $ 10,616 $ 103 $ — $ 22,593 Collectively evaluated for impairment 2,781 12,683 6,964 15,704 268 980 39,380 ASC 310-30 loans — 712 — — — — 712 Total allowance $ 6,069 $ 16,996 $ 11,949 $ 26,320 $ 371 $ 980 $ 62,685 Financing Receivables Individually evaluated for impairment $ 9,383 $ 39,574 $ 45,032 $ 145,233 $ 426 $ — $ 239,648 Collectively evaluated for impairment 886,114 3,383,189 1,082,786 1,662,802 73,011 39,976 7,127,878 ASC 310-30 loans 59,108 39,747 2,753 14,799 752 — 117,159 Loans Outstanding $ 954,605 $ 3,462,510 $ 1,130,571 $ 1,822,834 $ 74,189 $ 39,976 $ 7,484,685 As of September 30, 2016 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total (dollars in thousands) Allowance for loan and lease losses Individually evaluated for impairment $ 3,000 $ 3,846 $ 6,475 $ 12,278 $ 87 $ — $ 25,686 Collectively evaluated for impairment 3,199 13,328 6,515 12,837 351 1,047 37,277 ASC 310-30 loans 907 772 — — — — 1,679 Total allowance $ 7,106 $ 17,946 $ 12,990 $ 25,115 $ 438 $ 1,047 $ 64,642 Financing Receivables Individually evaluated for impairment $ 10,364 $ 54,005 $ 49,825 $ 101,840 $ 395 $ — $ 216,429 Collectively evaluated for impairment 918,710 3,249,974 1,079,295 1,721,219 74,301 42,477 7,085,976 ASC 310-30 loans 65,737 44,448 3,196 15,254 896 — 129,531 Loans Outstanding $ 994,811 $ 3,348,427 $ 1,132,316 $ 1,838,313 $ 75,592 $ 42,477 $ 7,431,936 The Company maintains an ALLL for acquired loans accounted for under ASC 310-30 as a result of impairment to loan pools arising from the periodic re-valuation of these loans. Any impairment in the individual pool is generally recognized in the current period as provision for loan and lease losses. Any improvement in the estimated cash flows, is generally not recognized immediately, but is instead reflected as an adjustment to the related loan pools yield on a prospective basis once any previously recorded impairment has been recaptured. The ALLL for ASC 310-30 loans totaled $0.7 million at March 31, 2017 , compared to $1.7 million at September 30, 2016 . During the three months ended March 31, 2017 and 2016 , loan pools accounted for under ASC 310-30 had a net reversal of provision of $1.1 million and $0.1 million , respectively. Net provision reversal for the six months ended March 31, 2017 and 2016 totaled $1.0 million and $0.3 million , respectively. The net reversals of provision for the periods ended March 31, 2017 were a result of updated assumptions being applied to one of the acquired mortgage pools which resulted in higher than expected cash flows. The net reversals of provision for the periods ended March 31, 2016 were driven by a result of actual cash flows being higher than expected cash flows. For acquired loans not accounted for under ASC 310-20 (purchased non-credit 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 reserve for unfunded loan commitments was $0.5 million at March 31, 2017 and September 30, 2016 and is recorded in other liabilities on the consolidated balance sheets.

Accounting for Certain Loans Ac

Accounting for Certain Loans Acquired with Deteriorated Credit Quality	6 Months Ended
	Mar. 31, 2017
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 that had deteriorated credit quality (ASC 310-30 loans). Loan accounting specific to these purchased credit impaired loans addresses differences between contractual cash flows expected to be collected from the initial investment in loans if those differences are attributable, at least in part, to credit quality. Several factors were considered when evaluating whether a loan was considered a purchased credit impaired loan, including the delinquency status of the loan, updated borrower credit status, geographic information, and updated loan-to-values (“LTV”). U.S. GAAP allows purchasers to aggregate purchased credit impaired loans acquired in the same fiscal quarter in one or more pools, provided that the loans have common risk characteristics. A pool is then accounted for as a single asset with a single composite interest rate and an aggregate expectation of cash flows. Loan pools are periodically reassessed to determine expected cash flows. In determining the expected cash flows, the timing of cash flows and prepayment assumptions for smaller, homogeneous loans are based on statistical models that take into account factors such as the loan interest rate, credit profile of the borrowers, the years in which the loans were originated, and whether the loans are fixed or variable rate loans. Prepayments may be assumed on large individual loans that consider similar prepayment factors listed above for smaller homogeneous loans. The re-assessment of purchased credit impaired loans resulted in the following changes in the accretable yield during the three and six months ended March 31, 2017 and 2016 : Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands) Balance at beginning of period $ 39,758 $ 41,882 $ 38,124 $ 44,489 Accretion (3,040 ) (2,261 ) (5,978 ) (4,590 ) Reclassification from (to) nonaccretable difference 1,987 222 6,559 (56 ) Balance at end of period $ 38,705 $ 39,843 $ 38,705 $ 39,843 The reclassification from nonaccretable difference noted in the table above represents 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 reclassification to nonaccretable difference noted in the table above represents instances where specific pools of loans are estimated to have a shortfall in the expected future cash flows compared to the contractual cash flows at the prior re-assessment date. The following table provides purchased credit impaired loans at March 31, 2017 and September 30, 2016 : March 31, 2017 September 30, 2016 Outstanding Balance 1 Recorded Investment 2 Carrying 3 Outstanding Balance 1 Recorded Investment 2 Carrying 3 (dollars in thousands) Residential real estate $ 69,261 $ 59,108 $ 59,108 $ 76,696 $ 65,737 $ 64,830 Commercial real estate 123,321 39,747 39,035 129,615 44,448 43,676 Commercial non real estate 11,361 2,753 2,753 11,588 3,196 3,196 Agriculture 18,474 14,799 14,799 19,174 15,254 15,254 Consumer 892 752 752 1,033 896 896 Total lending $ 223,309 $ 117,159 $ 116,447 $ 238,106 $ 129,531 $ 127,852 1 Represents the legal balance of ASC 310-30 loans. 2 Represents the book balance of ASC 310-30 loans. 3 Represents the book balance of ASC 310-30 loans net of the related allowance for loan and lease losses.

FDIC Indemnification Asset

FDIC Indemnification Asset	6 Months Ended
	Mar. 31, 2017
Banking and Thrift [Abstract]
FDIC Indemnification Asset	FDIC Indemnification Asset Under 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. As covered assets are resolved, whether it be 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 Real Estate Owned ("OREO"), any differences between the carrying value of the covered assets versus the payments received during the resolution process, that are reimbursable by the FDIC, are recognized as reductions in the FDIC indemnification asset. Any gains or losses realized from the resolution of covered assets reduce or increase, respectively, the amount recoverable from the FDIC. The following table represents a summary of the activity related to the FDIC indemnification asset for the three and six months ended March 31, 2017 and 2016 : Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands) Balance at beginning of period $ 9,887 $ 13,185 $ 10,777 $ 14,722 Amortization (1,114 ) (895 ) (1,981 ) (1,927 ) Changes in expected reimbursements from FDIC for changes in expected credit losses (133 ) 1 (105 ) (127 ) Changes in reimbursable expenses (299 ) (78 ) (538 ) (427 ) Reimbursements of covered losses to the FDIC 30 662 218 634 Balance at end of period $ 8,371 $ 12,875 $ 8,371 $ 12,875 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 agreements. The non-commercial loss share agreement ends June 4, 2020.

Derivative Financial Instrument

Derivative Financial Instruments	6 Months Ended
	Mar. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments In the normal course of business, the Company uses interest rate swaps to manage its interest rate risk and market risk in accommodating the needs of its customers. Also, the Company 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. Derivative instruments are recognized as either assets or liabilities in the accompanying consolidated financial statements and are measured at fair value. The following table summarizes the notional amounts and estimated fair values of the Company’s derivative instruments at March 31, 2017 and September 30, 2016 : March 31, 2017 Notional Amount Balance Sheet Location Positive Fair Value Negative Fair Value Derivatives not designated as hedging instruments: (dollars in thousands) Interest rate swaps $ 1,049,701 Liabilities $ 7,945 $ (20,466 ) Mortgage loan commitments 33,561 Assets 53 — Mortgage loan forward sale contracts 36,396 Liabilities — (53 ) September 30, 2016 Notional Amount Balance Sheet Location Positive Fair Value Negative Fair Value Derivatives not designated as hedging instruments: (dollars in thousands) Interest rate swaps $ 1,055,822 Liabilities $ 525 $ (81,974 ) Mortgage loan commitments 52,333 Assets 66 — Mortgage loan forward sale contracts 60,529 Liabilities — (66 ) 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. Amounts due from swap counterparties to reclaim cash collateral under the interest rate swap master netting arrangements have not been offset against the derivative balances. Credit-risk-related contingent features The Company has agreements with its derivative counterparties that contain a provision where if the Company 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 would be required to settle its obligations under the agreements. As of March 31, 2017 and September 30, 2016 , the termination value of derivatives in a net liability position related to these agreements was $16.9 million and $84.4 million , respectively, which includes accrued interest but excludes any adjustment for nonperformance risk. The Company has minimum collateral posting thresholds with its derivative counterparties and as of March 31, 2017 and September 30, 2016 , the Company had posted $32.1 million and $106.1 million , respectively, in eligible collateral. The effect of derivatives on the consolidated statements of comprehensive income for the three and six months ended March 31, 2017 and 2016 was as follows: Amount of Gain (Loss) Recognized in Income Three Months Ended Six Months Ended Location of Gain (Loss) Recognized in Income March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 Derivatives not designated as hedging instruments: (dollars in thousands) Interest rate swaps Noninterest income $ 1,592 $ (40,893 ) $ 60,568 $ (31,454 ) Mortgage loan commitments Noninterest income 158 76 53 52 Mortgage loan forward sale contracts Noninterest income (158 ) (76 ) (53 ) (52 ) Netting of Derivatives The Company has various financial assets and financial liabilities that are subject to enforceable master netting agreements or similar agreements. The Company has entered into an International Swaps Derivatives Association ("ISDA") master netting arrangement with various swap counterparties. Under the terms of the master netting arrangements, all transactions between the Company and the counterparty constitute a single business relationship such that in the event of default, the non-defaulting party is entitled to set off claims and apply property held by that party in respect of any transaction against obligations owed. Any payments, deliveries, or other transfers may be applied against each other and netted. The following tables present the Company's gross derivative financial assets and liabilities at March 31, 2017 and September 30, 2016 , and the related impact of enforceable master netting agreements and cash collateral, where applicable: Gross Amount Net Amount Presented in Consolidated Balance Sheets Held/Pledged Financial Instruments 1 Net March 31, 2017 (dollars in thousands) Derivative financial assets: Derivatives subject to master netting arrangement or similar arrangement $ 7,945 $ (7,945 ) $ — $ — $ — Derivative financial liabilities: Derivatives subject to master netting arrangement or similar arrangement (20,466 ) 7,945 (12,521 ) — (12,521 ) Total derivative financial liabilities $ (12,521 ) $ — $ (12,521 ) $ — $ (12,521 ) 1 The actual amount of collateral exceeds the fair value exposure, at the individual counterparty level, as of the date presented. Gross Amount Net Amount Presented in Consolidated Balance Sheets Held/Pledged Financial Instruments 1 Net September 30, 2016 (dollars in thousands) Derivative financial assets: Derivatives subject to master netting arrangement or similar arrangement $ 525 $ (525 ) $ — $ — $ — Derivative financial liabilities: Derivatives subject to master netting arrangement or similar arrangement (81,974 ) 525 (81,449 ) 81,449 — Total derivative financial liabilities $ (81,449 ) $ — $ (81,449 ) $ 81,449 $ — 1 The actual amount of collateral exceeds the fair value exposure, at the individual counterparty level, as of the date presented.

The Fair Value Option For Certa

The Fair Value Option For Certain Loans	6 Months Ended
	Mar. 31, 2017
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 and written loan commitments at fair value to assist in managing the interest rate risk for longer-term loans. This fair value option was elected upon the origination of these loans. Interest income is recognized in the same manner as interest on non-fair value loans. See Note 18 for additional disclosures regarding the fair value of the fair value option loans and written loan commitments. Long-term loans and written loan commitments 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 $4.9 million and $74.1 million at March 31, 2017 and September 30, 2016 , respectively. The total unpaid principal balance of these long-term loans was approximately $1.05 billion and $1.06 billion at March 31, 2017 and September 30, 2016 , respectively. The fair value of these loans and written loan commitments is included in total loans in the consolidated balance sheets and are grouped with commercial non real estate, commercial real estate, and agricultural loans in Note 5. There were no written loan commitments at March 31, 2017 and September 30, 2016 . As of March 31, 2017 and September 30, 2016 , there were loans with a fair value of $9.6 million and $9.4 million , respectively, which were greater than 90 days past due or in nonaccrual status with an unpaid principal balance of $11.0 million and $10.8 million , respectively. Changes in fair value for items for which the fair value option has been elected and the line items in which these changes are reported within the consolidated statements of comprehensive income are as follows for the three and six months ended March 31, 2017 and 2016 : Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 Noninterest Income Total Changes in Fair Value Noninterest Income Total Changes in Fair Value Noninterest Income Total Changes in Fair Value Noninterest Income Total Changes in Fair Value (dollars in thousands) Long-term loans and written loan commitments $ (5,216 ) $ (5,216 ) $ 35,955 $ 35,955 $ (69,218 ) $ (69,218 ) $ 21,054 $ 21,054 For long-term loans and written loan commitments, $0.3 million and $0.2 million for the three months ended March 31, 2017 and 2016 , respectively, and $0.3 million and $0.4 million for the six months ended March 31, 2017 and 2016 , 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.

Core Deposits and Other Intangi

Core Deposits and Other Intangibles	6 Months Ended
	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Core Deposits and Other Intangibles	Core Deposits and Other Intangibles A summary of intangible assets subject to amortization is as follows: Core Deposit Intangible Brand Customer Relationships Intangible Other Total As of March 31, 2017 (dollars in thousands) Gross carrying amount $ 67,018 $ 8,464 $ 16,089 $ 538 $ 92,109 Accumulated amortization (60,615 ) (4,982 ) (16,089 ) (80 ) (81,766 ) Net intangible assets $ 6,403 $ 3,482 $ — $ 458 $ 10,343 As of September 30, 2016 Gross carrying amount $ 67,018 $ 8,464 $ 16,089 $ 538 $ 92,109 Accumulated amortization (59,842 ) (4,700 ) (15,800 ) (35 ) (80,377 ) Net intangible assets $ 7,176 $ 3,764 $ 289 $ 503 $ 11,732 Amortization expense of intangible assets was $0.6 million and $0.7 million for the three months ended March 31, 2017 and 2016 , respectively, and $1.4 million for the six months ended March 31, 2017 and 2016 . 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: Amount (dollars in thousands) Remaining in 2017 $ 952 2018 1,614 2019 1,489 2020 1,363 2021 1,267 2022 and thereafter 3,658 Total $ 10,343

Loan Servicing Rights

Loan Servicing Rights	6 Months Ended
	Mar. 31, 2017
Transfers and Servicing [Abstract]
Loan Servicing Rights	Loan Servicing Rights Mortgage loans serviced for others are not included in the accompanying consolidated statements of financial condition. The following table is the activity for loan servicing rights and the related valuation allowance for the three and six months ended March 31, 2017 and 2016 : Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands) Loan servicing rights Beginning of period $ 5,286 $ — $ 5,794 $ — Additions — — — — Amortization 1 (380 ) — (888 ) — End of period $ 4,906 $ — $ 4,906 $ — Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands) Valuation allowance Beginning of period $ (8 ) $ — $ (13 ) $ — (Additions) / reductions 1 5 — 10 — End of period $ (3 ) $ — $ (3 ) $ — Loan servicing rights, net $ 4,903 $ — $ 4,903 $ — Servicing fees received $ 525 $ — $ 1,073 $ — Balance of loans serviced at: Beginning of period 823,375 — 868,865 — End of period 792,779 — 792,779 — 1 Changes to carrying amounts are reported net of loan servicing income on the consolidated statements of comprehensive income for the periods presented. Amortization of servicing rights is adjusted each quarter based upon analysis of portfolio attributes and factors, including an evaluation of historical prepayment activity and prospective industry consensus data. An independent third party is utilized to calculate the amortization and valuation based upon specific loan characteristics, prepayment speeds generated from a validation model utilizing both empirical and market derived data and discount rates. At March 31, 2017 , the constant prepayment rates (CPR) used to calculate the amortization averaged 12.1% . For valuation purposes, an average discount rate of 11.9% was utilized at March 31, 2017 . Based on the Company's analysis of mortgage servicing rights, a $0.0 million valuation reserve was recorded at March 31, 2017 and September 30, 2016 , respectively.

Securities Sold Under Agreement

Securities Sold Under Agreements to Repurchase	6 Months Ended
	Mar. 31, 2017
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities Sold Under Agreements to Repurchase	Securities Sold Under Agreements to Repurchase Securities sold under agreements to repurchase generally mature overnight following the transaction date. Securities underlying the agreements had an amortized cost of approximately $131.1 million and $151.8 million and fair value of approximately $128.9 million and $152.3 million at March 31, 2017 and September 30, 2016 , respectively. In most cases, 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 March 31, 2017 and September 30, 2016 . March 31, 2017 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater than 90 Days Total Repurchase agreements (dollars in thousands) Municipal securities $ 2,542 $ — $ — $ — $ 2,542 Mortgage-backed securities 121,930 — — — 121,930 Total repurchase agreements $ 124,472 $ — $ — $ — $ 124,472 September 30, 2016 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater than 90 Days Total Repurchase agreements (dollars in thousands) Municipal securities $ — $ — $ — $ — $ — Mortgage-backed securities 138,744 — — 2,944 141,688 Total repurchase agreements $ 138,744 $ — $ — $ 2,944 $ 141,688

FHLB Advances and Other Borrowi

FHLB Advances and Other Borrowings	6 Months Ended
	Mar. 31, 2017
Federal Home Loan Banks [Abstract]
FHLB Advances and Other Borrowings	FHLB Advances and Other Borrowings FHLB advances and other borrowings consist of the following at March 31, 2017 and September 30, 2016 : March 31, 2017 September 30, 2016 (dollars in thousands) Notes payable to Federal Home Loan Bank (FHLB), interest rates from 0.81% to 3.66% and maturity dates from May 2017 to July 2023, collateralized by real estate loans and FHLB stock, with various call dates at the option of the FHLB $ 246,000 $ 640,000 Federal Home Loan Bank fed funds advance, interest rate of 1.06%, maturity date of September 2017 17,000 231,000 Other 1,600 — Total 264,600 871,000 Fair value adjustment 1 24 37 Total FHLB advances and other borrowings $ 264,624 $ 871,037 1 Adjustment reflects the fair value adjustments related to the FHLB advances and notes payable assumed as part of the HF Financial acquisition. The Company has a $10.0 million revolving line of credit with a large retail bank, which expires on July 28, 2017 . The line of credit has an interest rate of one month LIBOR plus 200 basis points , with interest payable monthly. There is also an unused line fee of 0 .20% on the unused portion which is payable quarterly. The interest rate was 2.98% at March 31, 2017 . There were no outstanding advances on this line of credit at March 31, 2017 and September 30, 2016 . As of March 31, 2017 , based on its Federal Home Loan Bank stock holdings, the combined aggregate additional borrowing capacity of the Company with the Federal Home Loan Bank was $1.72 billion . Principal balances of loans pledged to the Federal Home Loan Bank to collateralize notes payable totaled $3.32 billion and $3.11 billion at March 31, 2017 and September 30, 2016 , respectively. As of March 31, 2017 , FHLB advances and other borrowings are due or callable (whichever is earlier) in subsequent fiscal years as follows: Amount (dollars in thousands) Remaining in 2017 $ 118,600 2018 31,000 2019 — 2020 — 2021 — 2022 and thereafter 115,000 Total $ 264,600

Subordinated Debentures and Sub

Subordinated Debentures and Subordinated Notes Payable	6 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Subordinated Debentures and Subordinated Notes Payable	Subordinated Debentures and Subordinated Notes Payable Junior Subordinated Deferrable Interest Debentures The Company has caused seven trusts to be created (or assumed as part of the HF Financial and Sunstate Bank acquisitions) that have issued and outstanding 73,400 shares, $1,000 par value, as of March 31, 2017 of Company Obligated Mandatorily Redeemable Preferred Securities (the "Preferred Securities"). These seven trusts were established and exist for the sole purpose of issuing the Preferred Securities and investing the proceeds in junior subordinated deferrable interest debentures (the "Debentures") issued by the Company. The Debentures constitute the sole assets of the seven trusts. The Preferred Securities provide for cumulative cash distributions calculated at a rate based on three-month LIBOR plus a range from 1.48% to 3.35% adjusted quarterly. The Company may, at one or more times, defer interest payments on the Debentures for up to 20 consecutive quarters following suspension of dividends on all capital stock, but not beyond the respective maturity date. At the end of any deferral period, all accumulated and unpaid interest must be paid. The Debentures have redemption dates ranging from January 7, 2033 to October 1, 2037 ; however, the Company has the option to shorten the respective maturity date for all seven Preferred Securities as the call option date has passed. Holders of the Preferred Securities have no voting rights. The Preferred Securities are unsecured and rank junior in priority of the payment to all of the Company's indebtedness and senior to the Company's common and preferred stock. The trusts’ ability to pay amounts due on the Preferred Securities is solely dependent upon the Company making payment on the related Debentures. The Company’s obligation under the Debentures and relevant trust agreements constitute a full, irrevocable, and unconditional guarantee on a subordinated basis by it of the obligations of the trusts under the Preferred Securities. For regulatory purposes the Debentures qualify as elements of capital. $73.5 million and $77.2 million of Debentures were eligible for treatment as Tier 1 capital, respectively, as of March 31, 2017 and September 30, 2016 . Relating to the trusts, the Company held as assets $2.5 million in common shares at March 31, 2017 and September 30, 2016 , respectively, which are included in other assets on the consolidated balance sheets. In the first quarter of fiscal year 2017 , the Company redeemed 5,000 shares of the HF Capital Trust V Debentures under the First Supplemental Indenture dated May 13, 2016. Subordinated Notes Payable In 2015, the Company issued $35.0 million of 4.875% fixed-to-floating rate subordinated notes that mature on August 15, 2025 through a private placement. The notes, which qualify as Tier 2 capital under capital rules in effect at March 31, 2017 , have an interest rate of 4.875% per annum, payable semi-annually on each February 15 and August 15 , which commenced on February 15, 2016 until August 15, 2020 , to but excluding the maturity date or date of 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 $0.2 million and $0.3 million at March 31, 2017 and September 30, 2016 , respectively. Proceeds from the private placement of subordinated notes repaid outstanding subordinated debt. Subordinated debentures and subordinated notes payable are summarized as follows: March 31, 2017 September 30, 2016 Amount Outstanding Common Shares Held in Other Assets Amount Outstanding Common Shares Held in Other Assets (dollars in thousands) Junior subordinated debentures payable to nonconsolidated 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 10,310 310 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 80,920 $ 2,520 Less: fair value adjustment 1 (2,455 ) (3,765 ) Total junior subordinated debentures payable, net of fair value adjustment 73,465 77,155 Subordinated notes payable Fixed to floating rate, 4.875% per annum 35,000 35,000 Less: unamortized debt issuance costs (245 ) (282 ) Total subordinated notes payable 34,755 34,718 Total subordinated debentures and subordinated notes payable $ 108,220 $ 111,873 1 Adjustment reflects the fair value adjustments related to the junior subordinated deferrable interest debentures assumed as part of the HF Financial acquisition.

Employee Benefit Plans

Employee Benefit Plans	6 Months Ended
	Mar. 31, 2017
Compensation and Retirement Disclosure [Abstract]
Employee Benefit Plans	Employee Benefit Plans Profit Sharing Plan The Company participates in a multiple employer 401(k) profit sharing plan (the Plan). All employees are eligible to participate, beginning with the first day of the month coincident with or immediately following the completion of one year of service and having reached the age of 21 . In addition to employee contributions, the Company may contribute discretionary amounts for eligible participants. Contribution rates for participating employees must be equal. The Company contributed $1.3 million and $0.6 million to the Plan for the three months ended March 31, 2017 and 2016 , respectively and $2.9 million and $2.0 million for the six months ended March 31, 2017 and 2016 , respectively. Defined Benefit Plan The Company acquired a noncontributory (cash balance) defined benefit pension plan from HF Financial which covers employees of HF Financial and its wholly-owned subsidiaries. Effective July 1, 2015, the plan was frozen which eliminates future contributions for qualified individuals. The plan has not been terminated, so the plan continues to exist with related benefit obligations and plan assets for those vested within the plan. Information relative to the components of net periodic benefit cost measured at/or for the three and six months ended March 31, 2017 and 2016 for the defined benefit plan is presented below: Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands) Net periodic benefit cost Service cost $ 12 $ — $ 24 $ — Interest cost 56 — 112 — Expected return on plan assets (64 ) — (128 ) — Amortization of prior losses 62 — 124 — Net periodic benefit cost $ 66 $ — $ 132 $ — The Company does not anticipate funding any contributions for fiscal year 2017 .

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [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 our controlling shareholder, approved the Great Western Bancorp, Inc. 2014 Omnibus Incentive Compensation Plan (the “2014 Plan”), the Great Western Bancorp, Inc. 2014 Non-Employee Director Plan (the “2014 Director Plan”), and the Great Western Bancorp, Inc. Executive Incentive Compensation Plan (the “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. 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 (typically 3 years ) has been met and/or 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 based compensation is recognized based on the number of awards that are ultimately expected to vest. Forfeitures are estimated based on historical turnover experience of qualified employees. 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 comprehensive income. For the three months ended March 31, 2017 and 2016 , stock compensation expense was $2.0 million and $0.7 million , respectively and $3.6 million and $1.8 million for the six months ended March 31, 2017 and 2016 , respectively. Related income tax benefits recognized were $0.7 million and $0.3 million for the three months ended March 31, 2017 and 2016 , respectively and $1.4 million and $0.7 million for the six months ended March 31, 2017 and 2016 , respectively. The following is a summary of the Plans’ restricted share and performance-based stock award activity as of March 31, 2017 and September 30, 2016 : March 31, 2017 September 30, 2016 Restricted Shares Common Weighted-Average Grant Date Fair Value Common Weighted-Average Grant Date Fair Value Restricted shares, beginning of fiscal year 160,335 $ 26.89 80,446 $ 18.18 Granted 89,135 39.36 113,543 30.95 Vested and issued (67,213 ) 27.00 (25,729 ) 18.11 Forfeited (1,868 ) 30.00 (7,925 ) 25.09 Canceled — — — — Restricted shares, end of period 180,389 $ 32.98 160,335 $ 26.89 Vested, but not issuable at end of period 32,759 $ 30.53 24,480 $ 26.14 Performance Shares Performance shares, beginning of fiscal year 236,185 $ 20.28 211,026 $ 18.00 Granted 40,204 39.43 43,371 30.78 Vested and issued — — (55 ) 18.00 Forfeited (3,158 ) 20.93 (18,157 ) 18.83 Canceled — — — — Performance shares, end of period 273,231 $ 23.09 236,185 $ 20.28 The number of performance shares granted is reflected in the above table at the 100% target performance level. The actual performance-based award payouts will vary based on the achievement of the pre-established targets and can range from 0% to 150% of the target amount. The outstanding number of performance shares reflected in the table represents the number of shares expected to be awarded based on estimated achievement of the goals as of March 31, 2017 . The maximum number of performance-based shares that could be issued if performance is attained at 150% of target based on the grants made to date was approximately 409,847 shares at March 31, 2017 . As of March 31, 2017 , there was $ 7.5 million of unrecognized compensation cost related to nonvested restricted stock awards expected to be recognized over a period of 2.7 years. The fair value of the vested, but not issued stock awards at March 31, 2017 , was $1.4 million .

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Mar. 31, 2017
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 agency mortgage-backed, states and political subdivisions, corporate debt, and other securities. Where Level 1 or Level 2 inputs are not available, securities are classified within Level 3 of the hierarchy. Interest Rate Swaps and Loans Interest rate swaps are valued by the Company's Swap Dealers using LIBOR rates. 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 hedge the interest rate risk and an adjustment for credit risk based on our 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 hedge 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 is required to post cash collateral to swap counterparties for interest rate derivative contracts that are in a liability 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 Company also has back to back swaps with loan customers, with corresponding swaps with an outside third party in exact offsetting terms. The following table presents the fair value measurements of assets and liabilities recognized in the accompanying consolidated balance sheets measured at fair value on a recurring basis and the level within the fair value hierarchy in which the fair value measurements fall at March 31, 2017 and September 30, 2016 : Fair Value Level 1 Level 2 Level 3 (dollars in thousands) As of March 31, 2017 U.S. Treasury securities $ 228,710 $ 228,710 $ — $ — Mortgage-backed securities 1,051,093 — 1,051,093 — States and political subdivision securities 70,061 — 68,837 1,224 Corporate debt securities — — — — Other 1,029 — 1,029 — Total securities available for sale $ 1,350,893 $ 228,710 $ 1,120,959 $ 1,224 Derivatives-assets $ 53 $ 53 $ — Derivatives-liabilities 12,574 — 12,574 — Fair value loans and written loan commitments 1,056,155 — 1,056,155 — Fair Value Level 1 Level 2 Level 3 (dollars in thousands) As of September 30, 2016 U.S. Treasury securities $ 230,980 $ 230,980 $ — $ — Mortgage-backed securities 1,024,838 — 1,024,838 — States and political subdivision securities 55,484 — 54,169 1,315 Corporate debt securities 5,022 — 5,022 — Other 1,062 — 1,062 — Total securities available for sale $ 1,317,386 $ 230,980 $ 1,085,091 $ 1,315 Derivatives-assets $ 66 $ — $ 66 $ — Derivatives-liabilities 81,515 — 81,515 — Fair value loans and written loan commitments 1,131,111 — 1,131,111 — The following table presents the changes in Level 3 financial instruments for the three and six months ended March 31, 2017 and 2016 : Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands) Balance, beginning of period $ 1,224 $ 1,458 $ 1,315 $ 1,835 Principal paydown — — (91 ) (77 ) Realized loss on securities — — — (300 ) Balance, end of period $ 1,224 $ 1,458 $ 1,224 $ 1,458 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 Real Estate Owned Other real estate owned consists of loan collateral that has been repossessed through foreclosure. This collateral is comprised of commercial and residential real estate. OREO 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. 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). 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 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 March 31, 2017 and September 30, 2016 : Fair Value Level 1 Level 2 Level 3 (dollars in thousands) As of March 31, 2017 Other real estate owned $ 3,071 $ — $ — $ 3,071 Impaired loans 217,055 — — 217,055 Loans held for sale, at lower of cost or fair value 4,902 — 4,902 — Loan servicing rights 4,903 — — 4,903 Property held for sale 5,258 — — 5,258 As of September 30, 2016 Other real estate owned $ 6,911 $ — $ — $ 6,911 Impaired loans 190,743 — — 190,743 Loans held for sale, at lower of cost or fair value 12,918 — 12,918 — Loan servicing rights 5,781 — — 5,781 Property held for sale 8,112 — — 8,112 The valuation techniques and significant unobservable inputs used to measure Level 3 fair value measurements at March 31, 2017 were as follows: Fair Value of Assets / (Liabilities) at March 31, 2017 Valuation Unobservable Range Weighted (dollars in thousands) Other real estate owned $ 3,071 Appraisal value Property specific adjustment N/A N/A Impaired loans 217,055 Appraisal value Property specific adjustment N/A N/A Loan servicing rights 4,903 Discounted cash flows Constant prepayment rate 9.0 - 21.0% 12.1% Property held for sale 5,258 Appraisal value Property specific adjustment N/A N/A Disclosures about Fair Value of Financial Instruments For financial instruments that have quoted market prices, those quotes are used to determine fair value. Financial instruments that have no defined maturity, have a remaining maturity of 180 days or less, or reprice frequently to a market rate are assumed to have a fair value that approximates carrying value, after taking into consideration any applicable credit risk. If no market quotes are available, financial instruments are valued by discounting the expected cash flows using an estimated current market interest rate for the financial instrument. The short maturity of the Company’s assets and liabilities results in having a significant number of financial instruments whose fair value equals or closely approximates carrying value. Such financial instruments are reported in the following consolidated balance sheet categories: cash and cash equivalents, securities sold under agreements to repurchase, and accrued interest. Fair value estimates are based on existing on and off-balance sheet financial instruments without attempting to estimate the value of anticipated future business and the value of assets and liabilities that are not considered financial instruments. Significant assets and liabilities that are not considered financial instruments include premises and equipment, deferred income taxes, goodwill, and core deposit and other intangibles. In addition, the tax ramifications related to the realization of unrealized gains and losses can have a significant effect on fair value estimates and have not been considered in the estimates. 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 balance sheet instruments as of March 31, 2017 and September 30, 2016 , are as follows: March 31, 2017 September 30, 2016 Level in Fair Value Hierarchy Carrying Amount Fair Carrying Amount Fair (dollars in thousands) Assets Cash and cash equivalents Level 1 $ 335,929 $ 335,929 $ 524,611 $ 524,611 Loans, net excluding fair valued loans and loans held for sale Level 3 7,573,684 7,506,331 7,473,973 7,433,851 Accrued interest receivable Level 2 43,690 43,690 49,531 49,531 Cash surrender value of life insurance policies Level 2 29,188 29,188 29,166 29,166 Federal Home Loan Bank stock Level 2 22,514 22,514 47,025 47,025 Liabilities Deposits Level 2 $ 9,091,918 $ 9,092,262 $ 8,604,790 $ 8,603,708 FHLB advances and other borrowings Level 2 264,624 265,315 871,037 874,763 Securities sold under repurchase agreements Level 2 124,472 124,472 141,688 141,688 Accrued interest payable Level 2 3,983 3,983 4,074 4,074 Subordinated debentures and subordinated notes payable Level 2 108,220 108,151 111,873 112,826 The following methods and assumptions were used in estimating the fair value of financial instruments that were not previously disclosed: Cash and cash equivalents: Due to the short term nature of cash and cash equivalents, the estimated fair value is equal to the carrying value and they are categorized as a Level 1 fair value measurement. Loans, net excluding fair valued loans and loans held for sale: The fair value of the loan portfolio is estimated using observable inputs including estimated cash flows, and discount rates based on interest rates currently being offered for loans with similar terms, to borrowers of similar credit quality. Loans held for investment are categorized as a Level 3 fair value measurement. Accrued interest receivable: Due to the nature of accrued interest receivable, the estimated fair value is equal to the carrying value and they are categorized as a Level 2 fair value measurement. Cash Surrender Value of Life Insurance Policies: Fair value is equal to the cash surrender value of the life insurance policies. Federal Home Loan Bank stock: The carrying amount of FHLB stock approximates its fair value as it can only be redeemed with the FHLB at par value. Federal Home Loan Bank stock has been categorized as a Level 2 fair value measurement. Deposits: The estimated fair value of deposits with no stated maturity, such as non-interest bearing demand deposits, savings, NOW, and money market accounts, is equal to the amount payable on demand. The fair value of interest-bearing time deposits is based on the discounted value of contractual cash flows of such deposits, taking into account the option for early withdrawal. The discount rate is estimated using the rates offered by the Company, at the respective measurement dates, for deposits of similar maturities. Deposits have been categorized as a Level 2 fair value measurement. FHLB advances and other borrowings: The fair value of FHLB advances and other borrowings is estimated using discounted cash flow analysis, based on current incremental borrowing rates for similar types of borrowing arrangements. In the absence of a reasonably precise methodology to determine the fair value of the credit agreement, carrying value has been used to represent fair value. FHLB advances and other borrowings have been categorized as a Level 2 fair value measurement. Securities sold under repurchase agreements: The Company’s repurchase agreements are overnight transactions that mature the day after the transaction, and as a result of this short-term nature, the estimated fair value equals the carrying value. Securities sold under repurchase agreements have been categorized as a Level 2 fair value measurement. Accrued interest payable: Due to the nature of accrued interest payable, the estimated fair value is equal to the carrying value and they are categorized as a Level 2 fair value measurement. Subordinated Debentures and Subordinated Notes Payable: The fair value of subordinated debentures and subordinated notes payable is estimated using discounted cash flow analysis, based on current incremental debt rates. Subordinated debentures and subordinated notes payable have been categorized as a Level 2 fair value measurement.

Earnings per Share

Earnings per Share	6 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share Basic earnings per common share is calculated by dividing net income available to common shareholders by the weighted average number of common shares outstanding during the period. Diluted earnings per common share is calculated by dividing net income available to common shareholders by the weighted average number of common shares outstanding determined for the basic earnings per share calculation plus the dilutive effect of stock compensation using the treasury stock method. The following information was used in the computation of basic and diluted earnings per share (EPS) for the three and six months ended March 31, 2017 and 2016 : Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands, except per share data) Net income $ 35,162 $ 30,674 $ 72,065 $ 61,135 Weighted average common shares outstanding 58,788,802 55,269,557 58,769,662 55,261,634 Dilutive effect of stock based compensation 284,867 139,319 263,125 139,530 Weighted average common shares outstanding for diluted earnings per share calculation 59,073,669 55,408,876 59,032,787 55,401,164 Basic earnings per share $ 0.60 $ 0.56 $ 1.23 $ 1.11 Diluted earnings per share $ 0.60 $ 0.55 $ 1.22 $ 1.10 The Company had 50,076 and 36,696 shares of unvested performance stock as of March 31, 2017 and 2016 , respectively, which were not included in the computation of diluted earnings per common share because performance conditions for vesting had not been met. The Company had 53,126 and 174,415 shares of anti-dilutive stock awards outstanding as of March 31, 2017 and 2016 , respectively.

Nature of Operations and Summ28

Nature of Operations and Summary of Significant Policies (Policies)	6 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated interim financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) and reflect all adjustments that are, in the opinion of management, necessary for the fair presentation of the financial position and results of operations for the periods presented. All such adjustments are of a normal recurring nature. Certain previously reported amounts have been reclassified to conform to the current presentation. The unaudited interim consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements for the year ended September 30, 2016 , which includes a description of significant accounting policies. The results of operations for interim periods are not necessarily indicative of the results that may be expected for the year or any other period. The accompanying unaudited consolidated financial statements include the accounts and results of operations of the Company and its subsidiaries after elimination of all significant intercompany accounts and transactions. The preparation of unaudited consolidated financial statements in conformity with U.S. GAAP requires management to make certain estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from these estimates.
Business Combinations	Business Combinations The Company accounts for business combinations under the acquisition method of accounting in accordance with ASC 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 in the consolidated statements of comprehensive income from the effective date of acquisition.
Use of Estimates	Use of Estimates U. S. GAAP requires management makes estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates.
Securities	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 in the consolidated statements of comprehensive 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 (with certain exceptions for debt securities noted below) 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 accumulated other comprehensive income (loss). Interest and dividends, including amortization of premiums and accretion of discounts, are recognized as interest or dividend 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 in the consolidated statements of comprehensive income.
Loans	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, generally 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. Accrual of interest is discontinued when management believes, after considering collection efforts and other factors, the borrower’s financial condition is such that collection of interest is doubtful, which is generally at 90 days past due. Generally, when loans are placed on nonaccrual status, 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 agribusiness 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 grants commercial, agricultural, consumer, residential real estate, 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, inventory, property and equipment, residential real estate, and income-producing commercial and agricultural properties. 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, 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 residential real estate, commercial real estate, commercial non real estate, agriculture, consumer and other lending. 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 commercial real estate lending class includes loans made to small and middle market businesses, including multifamily properties. Loans in this class are 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, and nature of pledged collateral. We consider 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 our 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, and nature of pledged collateral. We consider 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 guaranteed by owners; cashflows are most often our 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, and nature of pledged collateral. We consider these risk characteristics in assigning risk ratings and estimating 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 for 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 on a continuous basis. The Company generally does not risk rate 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 (“TDRs”) 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. Our TDRs include performing and nonperforming TDRs, which consist of loans that continue to accrue interest at the loan's original interest rate as we expect 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 we do 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 we move the loan to a performing status (performing TDR). If we do 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 our 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 (“ALLL”) and Unfunded Commitments The Company maintains an allowance for loan and lease losses at a level management believes is appropriate to reserve for credit losses inherent in our 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 is 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 in the consolidated statements of comprehensive income. Past due status is monitored as an indicator of credit deterioration. Loans that are 90 days or more past due are put on nonaccrual status unless the loan is well secured and in the process of collection. 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 our 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 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. 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 recognized. For acquired nonimpaired 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 nonimpaired 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. We maintain a reserve for unfunded commitments at a level we believe to be sufficient to absorb estimated probable losses related to unfunded credit facilities.
FDIC Indemnification Asset and Clawback Liability	FDIC Indemnification Asset and Clawback Liability In conjunction with a Federal Deposit Insurance Corporation (“FDIC”) assisted transaction of TierOne Bank in 2010, the Company entered into two loss share agreements with the FDIC, one covering certain single family residential mortgage loans with the claim period ending June 2020 and one covering commercial loans and other assets, in which the claim period ended in June 2015. The agreements cover a portion of realized losses on loans, foreclosed real estate and certain other assets. The Company has recorded assets on the consolidated balance sheets (i.e. indemnification assets) representing estimated future amounts recoverable from the FDIC. Fair values of loans covered by the loss sharing agreements 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 agreements. 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 comprehensive income. Although these assets are contractual receivables from the FDIC, there are no contractual interest rates. As part of the loss sharing agreements, 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 agreements that is contingent upon actual losses incurred over the life of the agreements 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 agreements. 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 agreements 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.
Goodwill	Goodwill Goodwill represents the cost in excess of the fair value of net assets acquired (including identifiable intangibles) in transactions accounted for as business acquisitions. Goodwill is evaluated annually for impairment. The Company performs its impairment evaluation as of June 30 of each fiscal year. If the implied fair value of goodwill is lower than its carrying amount, goodwill impairment is indicated and goodwill is written down to its implied fair value. Subsequent increases in goodwill are not recognized in the consolidated financial statements.
Core Deposits and Other Intangibles	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 purchase acquisitions. Brand intangible represents the value associated with the Bank charter . Customer relationships intangible represents the identifiable intangible value assigned to customer relationships arising from a purchase acquisition. Other intangibles represent contractual franchise arrangements under which the franchiser grants the franchisee the right to perform certain functions within a designated geographical area. 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 Intangible assets are evaluated for impairment whenever events or changes in circumstances indicate that the carrying value may not be recoverable.
Loan Servicing Rights	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 comprehensive income in proportion to and over the period of estimated net servicing income. Loan servicing rights are evaluated for impairment based upon the fair value of the rights as compared to the carrying amount. Impairment is determined by stratifying rights into groupings based on characteristics, such as interest rate, loan type and investor type. Impairment is recognized through a valuation allowance, to the extent that fair value is less than the carrying amount. If the Company later determines that all or a portion of the impairment no longer exists, a reduction of the allowance may be recorded as an increase to noninterest income. If the Company determines the impairment to be permanent, the valuation is written off against the loan servicing rights, which results in a new amortized balance. Changes in the valuation allowance are reported in mortgage banking income, net in the consolidated statements of comprehensive income. The fair value of loan servicing rights is subject to significant fluctuations as a result of changes in estimated and actual prepayment speeds and default rates and losses. Estimating future cash flows on the underlying mortgages is a difficult analysis and requires judgment based on the best information available. Based on the Company's analysis of loan servicing rights, a valuation allowance of $0.0 million was recorded during the three and six month periods ended March 31, 2017 and 2016 . Servicing fee income, which is reported in noninterest income, is recorded for fees earned for servicing loans. The fees are based on a contractual percentage of the outstanding balance or a fixed amount per loan and are recorded as income as earned. The amortization of loan servicing rights is netted against mortgage banking income, net in the consolidated statements of comprehensive income.
Bank Owned Life Insurance (BOLI)	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.
Derivatives	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 assets and 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. 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 assets and liabilities, depending on the rights or obligations under the contract, in fair value of derivatives on the consolidated balance sheet, with changes in fair value reported in net realized and unrealized gain (loss) on derivatives. 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 with changes in fair value recorded in noninterest income.
Stock Based Compensation	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.
Income Taxes	Income Taxes Income taxes are allocated pursuant to a tax-sharing arrangement, whereby the Company will pay federal and state income taxes as if it were filing on a stand-alone basis. 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 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	Defined Benefit Plan The Company assumed plan sponsorship of the HF Financial Corp. Pension Plan as part of the HF Financial acquisition. Defined benefit pension obligation and related costs are calculated using actuarial concepts and measurements. Three critical assumptions, the discount rate, the expected long-term rate of return on plan assets, and mortality rates are important elements of expense and/or benefit obligation measurements. Other assumptions involve employee demographic factors such as retirement patterns and turnover. The Company evaluates all assumptions annually. For the pension valuation performed as of September 30, 2016 , mortality assumptions were based on the RP-2014 mortality tables and the MP 2015 projection scales. The discount rate enables the Company to state expected future benefit payments as a present value on the measurement date. The Company determined the discount rate for the pension valuation as of September 30, 2016 by utilizing the standard duration index from the Citi Pension Discount Curve and Liability Index. A lower discount rate increases the present value of benefit obligations and increases pension expense. To determine expected long-term rate of return on defined benefit pension plan assets, the Company considers the current asset allocation of the defined benefit pension plan, as well as historical and expected returns on each asset class. A lower expected rate of return on defined pension plan assets will increase pension expense. The Company recognizes the over- or under-funded status of a plan as an other asset or other liability in the consolidated balance sheets as measured by the difference between the fair value of the plan assets and the projected benefit obligation. When recorded, unrecognized prior service costs and actuarial gains and losses are recognized as a component of accumulated other comprehensive income (loss).
Revenue Recognition	Revenue Recognition The Company recognizes revenue as it is earned based on contractual terms, as transactions occur, or as services are provided and collectability is reasonably assured. Certain specific policies related to service charges and other fees include the following: Deposit Service Charges Service charges on deposit accounts are primarily fees related to customer overdraft events and not sufficient funds fees, net of any refunded fees, and are recognized as transactions occur and services are provided. Service charges on deposit accounts also relate to monthly fees based on minimum balances, and are earned as transactions occur and services are provided. Interchange Fees Interchange fees include interchange income from consumer debit card transactions processed through card association networks. Interchange income is a fee paid by a merchant bank to the card-issuing bank through the interchange network. Interchange fees are set by the card association networks and are based on cardholder purchase volumes. Wealth Management Fees Wealth management fees include commission income from financial planning, investment management and insurance operations.
Comprehensive Income	Comprehensive Income Comprehensive income consists of net income and other comprehensive income, net of applicable income taxes. Other comprehensive income (loss) consists entirely of unrealized appreciation (depreciation) on available for sale securities.
Subsequent Events	Subsequent Events The Company has evaluated all events or transactions that occurred through the date the Company issued these financial statements. Other than those events described below, there were no other material events that would require recognition in the consolidated financial statements or disclosure in the notes to the consolidated financial statements.
New Accounting Pronouncements	New Accounting Pronouncements In March 2017, the Financial Accounting Standards Board (FASB) issued ASU 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities, which shortens the amortization period for certain callable debt securities held at a premium to the earliest call date. There is no accounting change for debt securities held at a discount. ASU 2017-08 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. The Company is currently evaluating the potential impact of ASU 2017-08 on our consolidated financial statements. In March 2017, the FASB issued ASU 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, which requires an employer to report the service cost component in the same line item as other compensation costs arising from services rendered by employees in the income statement with the other components of the net benefit cost presented below the income from operations line in the income statement. ASU 2017-07 will be effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017, with early adoption permitted as of the beginning of the annual period. The Company is currently evaluating the potential impact of ASU 2017-07 on our consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, which eliminates Step 2 from the goodwill impairment test. Under this ASU, an entity should perform its annual or interim goodwill impairment test by comparing the fair value of the reporting unit with its carrying amount, and should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value with the loss not exceeding the total amount of goodwill allocated to that reporting unit. ASU 2017-04 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. The Company is currently evaluating the potential impact of ASU 2017-04 on our consolidated financial statements. In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying 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. The amendment provides a screen to determine when an integrated set of assets and activities (a "set") is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. The amendment also provides a more robust framework to use in determining when a set of assets and activities is a business. ASU 2017-01 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. The Company is currently evaluating the potential impact of ASU 2017-01 on our 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 alters how a decision maker needs to consider indirect interests in a variable interest entity held through an entity under common control and simplifies that analysis to require consideration of only an entity’s proportionate indirect interest in a VIE held through a common control party. ASU 2016-17 amends ASU 2015-02, Consolidations (Topic 810): Amendments to the Consolidation Analysis , which was not effective for the Company in the current fiscal year. ASU 2016-17 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. The Company is currently evaluating the potential impact of ASU 2016-17 on our 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 addresses improvement in accounting for income tax consequences of intra-equity transfers of assets other than inventory. This update requires 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 eliminates the exception for an intra-equity transfer for assets other than inventory. ASU 2016-16 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. The amendment requires the use of a modified retrospective transaction approach through a cumulative effect adjustment directly to retained earnings as of the beginning of adoption. The Company is currently evaluating the potential impact of ASU 2016-16 on our 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 addresses 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. ASU 2016-15 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. The amendment requires the use of the retrospective transaction approach for adoption. The Company is currently evaluating the potential impact of ASU 2016-15 on our consolidated financial statements. In June 2016, the FASB issued ASU No. 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. The ASU 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 ("CECL") model. The ASU 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. ASU 2016-13 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 amendment requires the use of the modified retrospective approach for adoption. ASU 2016-13 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 amendment requires the use of the modified retrospective approach for adoption. The Company is currently evaluating the potential impact of ASU 2016-13 on our consolidated financial statements. In March 2016, the FASB issued ASU No. 2016-09, Compensation - Stock Based Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting , which addresses several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU 2016-09 is effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2016. Earlier application is permitted. If an entity early adopts the amendments in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period. An entity that elects early adoption must adopt all of the amendments in the same period. The Company is currently evaluating the potential impact of ASU 2016-09 on our consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02 , Leases (Topic 842) , which requires that lessees recognize most leases on the balance sheet. This will increase reported assets and liabilities, as lessees will be required to recognize a right-of-use asset along with a lease liability, measured on a discounted basis. Lessees are allowed to account for short-term leases (those with a term of twelve months or less) off-balance sheet. ASU 2016-02 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The Company is currently evaluating the potential impact of ASU 2016-02 on our consolidated financial statements. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10) - Recognition and Measurement of Financial Assets and Financial Liabilities, which addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments. ASU 2016-01 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. The Company is currently evaluating the potential impact of ASU 2016-01 on our consolidated financial statements. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) , which implements a common revenue standard that clarifies the principles for recognizing revenue. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. In August 2015, the FASB issued ASU No. 2015-14 which deferred the effective date of ASU No. 2014-09 to annual reporting periods beginning after December 15, 2017. In March 2016, the FASB issued ASU No. 2016-08, which intends to improve the operability and understandability of the implementation guidance on principal versus agent considerations. In April 2016, the FASB issued ASU No. 2016-10, which clarifies guidance pertaining to the identification of performance obligations and the licensing implementation. In May 2016, the FASB issued ASU Nos. 2016-11 and 2016-12, which further clarify guidance and provide practical expedients related to the adoption of ASU No. 2014-09. In December 2016, the FASB issued ASU 2016-19, Technical Corrections and Improvements to Topic 606, which provides additional clarification and improvements for the following areas: loan guarantee fees, contract costs-impairment testing, provision for losses on construction-type and production-type contracts, cost capitalization guidance, and disclosure requirements. The standard permits the use of either the retrospective or cumulative effect transition method. In March 2017, the FASB issued ASU No. 2017-05, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets, which provides guidance for recognizing gains and losses from the transfer of nonfinancial assets in contracts with noncustomers. The Company is currently evaluating the potential impact of these standards on our consolidated financial statements.

Nature of Operations and Summ29

Nature of Operations and Summary of Significant Policies (Tables)	6 Months Ended
	Mar. 31, 2017
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 A summary of intangible assets subject to amortization is as follows: Core Deposit Intangible Brand Customer Relationships Intangible Other Total As of March 31, 2017 (dollars in thousands) Gross carrying amount $ 67,018 $ 8,464 $ 16,089 $ 538 $ 92,109 Accumulated amortization (60,615 ) (4,982 ) (16,089 ) (80 ) (81,766 ) Net intangible assets $ 6,403 $ 3,482 $ — $ 458 $ 10,343 As of September 30, 2016 Gross carrying amount $ 67,018 $ 8,464 $ 16,089 $ 538 $ 92,109 Accumulated amortization (59,842 ) (4,700 ) (15,800 ) (35 ) (80,377 ) Net intangible assets $ 7,176 $ 3,764 $ 289 $ 503 $ 11,732

Acquisition Activity (Tables)

Acquisition Activity (Tables)	6 Months Ended
	Mar. 31, 2017
Business Combinations [Abstract]
Schedule of acquisition activity	The following table presents the acquired loan data for the HF Financial acquisition. Fair Value of Acquired Loans at Acquisition Date Gross Contractual Amounts Receivable at Acquisition Date Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected (Unaudited, dollars in thousands) Acquired receivables subject to ASC 310-30 $ 51,532 $ 83,710 $ 28,516 Acquired receivables not subject to ASC 310-30 812,209 998,255 9,572 The following summarizes consideration paid and an allocation of purchase price to net assets acquired. Number of Shares Amount (dollars in thousands) Equity consideration: Common stock issued 3,448,119 $ 107,478 Non-equity consideration: Cash 34,487 Total consideration paid 141,965 Fair value of net assets acquired including identifiable intangible assets 100,749 Goodwill $ 41,216
Schedule of assets acquired and liabilities assumed	The following table summarizes the assets acquired and liabilities assumed which were recorded on the consolidated balance sheet as of the date of merger of HF Financial: Fair Value (dollars in thousands) Identifiable assets acquired: Cash and cash equivalents $ 18,818 Investment securities 165,052 Loans 863,741 Premises and equipment 19,220 Accrued interest receivable 4,117 Other repossessed property 4 Intangible assets 7,877 Loan servicing rights 6,573 Other assets 36,076 Total identifiable assets acquired $ 1,121,478 Liabilities assumed: Deposits $ 863,121 FHLB advances and other borrowings 115,881 Subordinated debentures 21,110 Other liabilities 20,617 Total liabilities assumed 1,020,729 Fair value of net identifiable assets acquired 100,749 Net purchase price 141,965 Goodwill $ 41,216
Schedule of pro forma information	The following unaudited pro forma combined results of operations of the Company and HF Financial presents results as if the acquisition had been completed as of the beginning of each period indicated. The unaudited pro forma combined results of operations are presented solely for information purposes and are not intended to represent or be indicative of the consolidated results of operations that the Company would have reported had this transaction been completed as of the dates and for the periods presented, nor are they necessarily indicative of future results. In particular, no adjustments have been made to eliminate the amount of HF Financial's provision for loan and lease losses incurred prior to the acquisition date that would not have been necessary had the acquired loans been recorded at fair value as of the beginning of each period indicated. In accordance with Article 11 of SEC Regulation S-X, transaction costs directly attributable to the acquisition have been excluded. Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (Unaudited, dollars in thousands, except per share data) Net interest income $ 97,399 $ 95,940 $ 196,042 $ 191,383 Net income 35,162 32,743 72,065 64,682 Basic earnings per share 0.60 0.59 1.23 1.17 Fully diluted earnings per share 0.60 0.59 1.22 1.17
Schedule of total contractually required principal and interest	The table below summarizes the total contractually required principal and interest cash payments, management's estimate of expected total cash payments and fair value of the loans as of acquisition date for purchased credit impaired loans. Contractually required principal and interest payments have been adjusted for estimated prepayments. Amount (Unaudited, dollars in thousands) Contractually required principal and interest $ 83,710 Non-accretable difference (28,516 ) Cash flows expected to be collected 55,194 Accretable yield (3,662 ) Total purchased credit impaired loans acquired $ 51,532

Securities Available for Sale (

Securities Available for Sale (Tables)	6 Months Ended
	Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Schedule of amortized cost and fair value of investments	The amortized cost and approximate fair value of investments in securities, all of which are classified as available for sale according to management’s intent, are summarized as follows: Amortized Gross Unrealized Gains Gross Unrealized Losses Estimated (dollars in thousands) As of March 31, 2017 U.S. Treasury securities $ 227,521 $ 1,195 $ (6 ) $ 228,710 Mortgage-backed securities: Government National Mortgage Association 592,330 419 (7,654 ) 585,095 Federal National Mortgage Association 271,184 40 (2,356 ) 268,868 Small Business Assistance Program 198,313 342 (1,525 ) 197,130 States and political subdivision securities 71,288 81 (1,308 ) 70,061 Corporate debt securities — — — — Other 1,013 16 — 1,029 Total $ 1,361,649 $ 2,093 $ (12,849 ) $ 1,350,893 Amortized Gross Unrealized Gains Gross Unrealized Losses Estimated (dollars in thousands) As of September 30, 2016 U.S. Treasury securities $ 227,007 $ 3,973 $ — $ 230,980 Mortgage-backed securities: Government National Mortgage Association 664,529 3,172 (1,922 ) 665,779 Federal National Mortgage Association 212,452 1,324 — 213,776 Small Business Assistance Program 142,921 2,362 — 145,283 States and political subdivision securities 55,525 123 (164 ) 55,484 Corporate debt securities 4,998 24 — 5,022 Other 1,013 49 — 1,062 Total $ 1,308,445 $ 11,027 $ (2,086 ) $ 1,317,386
Schedule of amortized cost and fair value of investments by contractual maturity	The amortized cost and approximate fair value of debt securities available for sale as of March 31, 2017 and September 30, 2016 , by contractual maturity, are shown below. Maturities of mortgage-backed securities may differ from contractual maturities because the mortgages underlying the securities may be called or repaid without penalty. March 31, 2017 September 30, 2016 Amortized Estimated Amortized Estimated (dollars in thousands) Due in one year or less $ 30,263 $ 30,307 $ 3,706 $ 3,709 Due after one year through five years 248,718 249,230 265,253 269,242 Due after five years through ten years 19,706 19,112 18,449 18,413 Due after ten years 122 122 122 122 298,809 298,771 287,530 291,486 Mortgage-backed securities 1,061,827 1,051,093 1,019,902 1,024,838 Securities without contractual maturities 1,013 1,029 1,013 1,062 Total $ 1,361,649 $ 1,350,893 $ 1,308,445 $ 1,317,386
Schedule of gross unrealized losses on investments	The following table presents the Company’s gross unrealized losses and approximate fair value in investments, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position: Less than 12 months 12 months or more Total Estimated Unrealized Estimated Unrealized Estimated Unrealized (dollars in thousands) As of March 31, 2017 U.S. Treasury securities $ 19,539 $ (6 ) $ — $ — $ 19,539 $ (6 ) Mortgage-backed securities 602,146 (6,030 ) 276,282 (5,505 ) 878,428 (11,535 ) States and political subdivision securities 53,052 (1,308 ) — — 53,052 (1,308 ) Total $ 674,737 $ (7,344 ) $ 276,282 $ (5,505 ) $ 951,019 $ (12,849 ) Less than 12 months 12 months or more Total Estimated Unrealized Estimated Unrealized Estimated Unrealized (dollars in thousands) As of September 30, 2016 U.S. Treasury securities $ — $ — $ — $ — $ — $ — Mortgage-backed securities $ 17,528 $ (6 ) $ 284,995 $ (1,916 ) $ 302,523 $ (1,922 ) States and political subdivision securities 27,933 (164 ) — — 27,933 (164 ) Total $ 45,461 $ (170 ) $ 284,995 $ (1,916 ) $ 330,456 $ (2,086 )
Schedule of net unrealized gains (losses) on securities	The components of accumulated other comprehensive income (loss) from net unrealized gains (losses) on securities available for sale for the three and six months ended March 31, 2017 and 2016 , are as follows: Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands) Beginning balance accumulated other comprehensive income (loss) $ (7,776 ) $ (5,289 ) $ 5,534 $ 2,318 Net unrealized holding gain (loss) arising during the period 1,727 16,102 (19,741 ) 4,187 Reclassification adjustment for net gain (loss) realized in net income 44 24 44 (330 ) Net change in unrealized gain (loss) before income taxes 1,771 16,126 (19,697 ) 3,857 Income tax (expense) benefit (673 ) (6,128 ) 7,485 (1,466 ) Net change in unrealized gain (loss) on securities after taxes 1,098 9,998 (12,212 ) 2,391 Ending balance accumulated other comprehensive income (loss) $ (6,678 ) $ 4,709 $ (6,678 ) $ 4,709

Loans (Tables)

Loans (Tables)	6 Months Ended
	Mar. 31, 2017
Receivables [Abstract]
Schedule of loans receivable	The composition of loans as of March 31, 2017 and September 30, 2016 , is as follows: March 31, 2017 September 30, 2016 (dollars in thousands) Residential real estate $ 971,374 $ 1,020,958 Commercial real estate 3,850,835 3,754,107 Commercial non real estate 1,690,149 1,673,166 Agriculture 2,114,287 2,168,937 Consumer 74,718 76,273 Other 39,976 42,477 Ending balance 8,741,339 8,735,918 Less: Unamortized discount on acquired loans (34,812 ) (39,947 ) Unearned net deferred fees and costs and loans in process (9,101 ) (13,327 ) Total $ 8,697,426 $ 8,682,644
Schedule of the Company's nonaccrual loans	The following table presents the Company’s nonaccrual loans at March 31, 2017 and September 30, 2016 , excluding ASC 310-30 loans. Loans greater than 90 days past due and still accruing interest as of March 31, 2017 and September 30, 2016 , were $3.8 million and $2.0 million , respectively. March 31, 2017 September 30, 2016 Nonaccrual loans (dollars in thousands) Residential real estate $ 5,290 $ 5,962 Commercial real estate 13,165 13,870 Commercial non real estate 27,273 27,280 Agriculture 70,134 66,301 Consumer 193 223 Total $ 116,055 $ 113,636
Schedule of the composition of the loan portfolio by internal risk rating	This table is presented net of unamortized discount on acquired loans and excludes loans measured at fair value with changes in fair value reported in earnings of $1.06 billion at March 31, 2017 and $1.13 billion at September 30, 2016 : As of March 31, 2017 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total Credit Risk Profile by Internally Assigned Grade (dollars in thousands) Grade: Pass $ 881,321 $ 3,433,051 $ 1,115,087 $ 1,447,894 $ 73,646 $ 39,976 $ 6,990,975 Watchlist 3,962 68,585 36,378 215,434 98 — 324,457 Substandard 9,520 44,298 35,687 173,766 445 — 263,716 Doubtful 357 519 5,459 206 — — 6,541 Ending balance 895,160 3,546,453 1,192,611 1,837,300 74,189 39,976 7,585,689 Loans covered by FDIC loss sharing agreements 64,681 — — — — — 64,681 Total $ 959,841 $ 3,546,453 $ 1,192,611 $ 1,837,300 $ 74,189 $ 39,976 $ 7,650,370 As of September 30, 2016 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total Credit Risk Profile by Internally Assigned Grade (dollars in thousands) Grade: Pass $ 919,224 $ 3,276,048 $ 1,093,913 $ 1,514,344 $ 75,065 $ 42,477 $ 6,921,071 Watchlist 4,741 81,148 37,283 204,326 110 — 327,608 Substandard 10,885 57,415 42,319 130,569 417 — 241,605 Doubtful 130 147 395 630 — — 1,302 Ending balance 934,980 3,414,758 1,173,910 1,849,869 75,592 42,477 7,491,586 Loans covered by FDIC loss sharing agreements 73,272 — — — — — 73,272 Total $ 1,008,252 $ 3,414,758 $ 1,173,910 $ 1,849,869 $ 75,592 $ 42,477 $ 7,564,858
Schedule of past due loans	The following table presents the Company’s past due loans at March 31, 2017 and September 30, 2016 . 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 $1.06 billion at March 31, 2017 and $1.13 billion at September 30, 2016 . 30-59 Days Past Due 60-89 Days Past Due 90 Days or Greater Past Due Total Current Total Financing Receivables As of March 31, 2017 (dollars in thousands) Residential real estate $ 2,943 $ 869 $ 1,704 $ 5,516 $ 889,644 $ 895,160 Commercial real estate 386 — 4,909 5,295 3,541,158 3,546,453 Commercial non real estate 2,118 670 16,422 19,210 1,173,401 1,192,611 Agriculture 9,408 2,822 10,998 23,228 1,814,072 1,837,300 Consumer 71 3 42 116 74,073 74,189 Other — — — — 39,976 39,976 Ending balance 14,926 4,364 34,075 53,365 7,532,324 7,585,689 Loans covered by FDIC loss sharing agreements 1,430 642 578 2,650 62,031 64,681 Total $ 16,356 $ 5,006 $ 34,653 $ 56,015 $ 7,594,355 $ 7,650,370 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, 2016 (dollars in thousands) Residential real estate $ 828 $ 548 $ 2,063 $ 3,439 $ 931,541 $ 934,980 Commercial real estate 1,765 1,959 3,745 7,469 3,407,289 3,414,758 Commercial non real estate 1,588 5,515 9,594 16,697 1,157,213 1,173,910 Agriculture (26 ) 709 11,549 12,232 1,837,637 1,849,869 Consumer 209 20 28 257 75,335 75,592 Other — — — — 42,477 42,477 Ending balance 4,364 8,751 26,979 40,094 7,451,492 7,491,586 Loans covered by FDIC loss sharing agreements 1,404 1,173 367 2,944 70,328 73,272 Total $ 5,768 $ 9,924 $ 27,346 $ 43,038 $ 7,521,820 $ 7,564,858
Schedule of impaired loans	The average recorded investment on impaired loans and interest income recognized on impaired loans for the three and six months ended March 31, 2017 and 2016 , respectively, are as follows: Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status (dollars in thousands) Residential real estate $ 9,565 $ 126 $ 12,124 $ 290 $ 9,831 $ 240 $ 12,204 $ 439 Commercial real estate 44,807 545 83,642 2,004 47,873 1,215 78,345 3,473 Commercial non real estate 46,304 358 40,450 766 47,477 780 48,798 1,122 Agriculture 128,919 1,326 109,473 3,256 119,892 3,193 91,013 5,695 Consumer 389 12 308 25 391 27 282 42 Total $ 229,984 $ 2,367 $ 245,997 $ 6,341 $ 225,464 $ 5,455 $ 230,642 $ 10,771 The following table presents the Company’s impaired loans. This table excludes loans covered by FDIC loss sharing agreements: March 31, 2017 September 30, 2016 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance Related Allowance Impaired loans: (dollars in thousands) With an allowance recorded: Residential real estate $ 6,243 $ 6,916 $ 3,288 $ 6,244 $ 6,886 $ 3,000 Commercial real estate 25,935 30,199 3,601 29,965 32,349 3,846 Commercial non real estate 27,195 28,537 4,985 34,526 35,283 6,475 Agriculture 83,940 95,814 10,616 71,501 80,842 12,278 Consumer 421 433 103 383 393 87 Total impaired loans with an allowance recorded 143,734 161,899 22,593 142,619 155,753 25,686 With no allowance recorded: Residential real estate 3,140 4,830 — 4,120 5,807 — Commercial real estate 13,639 14,295 — 24,040 24,660 — Commercial non real estate 17,837 22,317 — 15,299 16,469 — Agriculture 61,293 63,326 — 30,339 31,907 — Consumer 5 5 — 12 12 — Total impaired loans with no allowance recorded 95,914 104,773 — 73,810 78,855 — Total impaired loans $ 239,648 $ 266,672 $ 22,593 $ 216,429 $ 234,608 $ 25,686 The following table provides purchased credit impaired loans at March 31, 2017 and September 30, 2016 : March 31, 2017 September 30, 2016 Outstanding Balance 1 Recorded Investment 2 Carrying 3 Outstanding Balance 1 Recorded Investment 2 Carrying 3 (dollars in thousands) Residential real estate $ 69,261 $ 59,108 $ 59,108 $ 76,696 $ 65,737 $ 64,830 Commercial real estate 123,321 39,747 39,035 129,615 44,448 43,676 Commercial non real estate 11,361 2,753 2,753 11,588 3,196 3,196 Agriculture 18,474 14,799 14,799 19,174 15,254 15,254 Consumer 892 752 752 1,033 896 896 Total lending $ 223,309 $ 117,159 $ 116,447 $ 238,106 $ 129,531 $ 127,852 1 Represents the legal balance of ASC 310-30 loans. 2 Represents the book balance of ASC 310-30 loans. 3 Represents the book balance of ASC 310-30 loans net of the related allowance for loan and lease losses.
Summary of troubled debt restructurings on accruing and nonaccrual loans	The following table presents the recorded value of the Company’s TDR balances as of March 31, 2017 and September 30, 2016 : March 31, 2017 September 30, 2016 Accruing Nonaccrual Accruing Nonaccrual (dollars in thousands) Residential real estate $ 328 $ 614 $ 370 $ 937 Commercial real estate 5,302 2,178 18,250 2,356 Commercial non real estate 4,859 2,033 8,102 4,789 Agriculture 28,162 38,674 19,823 28,688 Consumer 4 29 23 8 Total $ 38,655 $ 43,528 $ 46,568 $ 36,778 The following table presents a summary of all accruing loans restructured in TDRs during the three months ended March 31, 2017 and 2016 , respectively: Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Residential real estate Rate modification — $ — $ — — $ — $ — Term extension — — — — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total residential real estate — — — — — — Commercial real estate Rate modification — — — — — — Term extension — — — — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — 3 6,714 6,714 Total commercial real estate — — — 3 6,714 6,714 Commercial non real estate Rate modification — — — 1 49 49 Term extension — — — — — — Payment modification 2 93 93 1 70 70 Bankruptcy — — — — — — Other — — — 3 3,849 3,849 Total commercial non real estate 2 93 93 5 3,968 3,968 Agriculture Rate modification — — — — — — Term extension 2 8,434 8,434 5 4,941 4,941 Payment modification — — — 4 989 989 Bankruptcy — — — — — — Other — — — — — — Total agriculture 2 8,434 8,434 9 5,930 5,930 Consumer Rate modification — — — — — — Term extension — — — — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total consumer — — — — — — Total accruing 4 $ 8,527 $ 8,527 17 $ 16,612 $ 16,612 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 accruing loans restructured in TDRs during the six months ended March 31, 2017 and 2016 , respectively: Six Months Ended March 31, 2017 Six Months Ended March 31, 2016 Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Residential real estate Rate modification — $ — $ — — $ — $ — Term extension — — — — — — Payment modification 1 9 9 — — — Bankruptcy — — — — — — Other — — — — — — Total residential real estate 1 9 9 — — — Commercial real estate Rate modification — — — — — — Term extension — — — 2 1,898 1,898 Payment modification — — — — — — Bankruptcy — — — — — — Other — — — 3 6,714 6,714 Total commercial real estate — — — 5 8,612 8,612 Commercial non real estate Rate modification — — — 1 49 49 Term extension — — — 1 58 58 Payment modification 4 526 526 1 70 70 Bankruptcy — — — — — — Other — — — 3 3,849 3,849 Total commercial non real estate 4 526 526 6 4,026 4,026 Agriculture Rate modification — — — — — — Term extension 2 8,434 8,434 13 26,914 26,914 Payment modification — — — 4 989 989 Bankruptcy — — — — — — Other — — — — — — Total agriculture 2 8,434 8,434 17 27,903 27,903 Consumer Rate modification — — — — — — Term extension — — — — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total consumer — — — — — — Total accruing 7 $ 8,969 $ 8,969 28 $ 40,541 $ 40,541 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 non-accruing loans restructured in TDRs during the three months ended March 31, 2017 and 2016 : Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Residential real estate Rate modification — $ — $ — — $ — $ — Term extension — — — — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total residential real estate — — — — — — Commercial real estate Rate modification — — — — — — Term extension — — — — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total commercial real estate — — — — — — Commercial Non Real Estate Rate modification — — — — — — Term extension — — — — — — Payment modification — — — 1 364 364 Bankruptcy — — — — — — Other — — — — — — Total commercial non real estate — — — 1 364 364 Agriculture Rate modification — — — — — — Term extension 6 12,988 12,988 — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total agriculture 6 12,988 12,988 — — — Consumer Rate modification — — — — — — Term extension 3 21 21 — — — Payment modification — — — — — — Bankruptcy — — — 1 8 8 Other — — — — — — Total consumer 3 21 21 1 8 8 Total non-accruing 9 $ 13,009 $ 13,009 2 $ 372 $ 372 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 non-accruing loans restructured in TDRs during the six months ended March 31, 2017 and 2016 : Six Months Ended March 31, 2017 Six Months Ended March 31, 2016 Recorded Investment Recorded Investment Number Pre-Modification Post-Modification Number Pre-Modification Post-Modification (dollars in thousands) Residential real estate Rate modification — $ — $ — — $ — $ — Term extension — — — — — — Payment modification 1 21 21 1 187 187 Bankruptcy — — — — — — Other — — — — — — Total residential real estate 1 21 21 1 187 187 Commercial real estate Rate modification — — — — — — Term extension — — — — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total commercial real estate — — — — — — Commercial Non Real Estate Rate modification — — — — — — Term extension — — — — — — Payment modification — — — 2 760 760 Bankruptcy — — — — — — Other — — — — — — Total commercial non real estate — — — 2 760 760 Agriculture Rate modification — — — — — — Term extension 6 12,988 12,988 — — — Payment modification — — — — — — Bankruptcy — — — — — — Other — — — — — — Total agriculture 6 12,988 12,988 — — — Consumer Rate modification — — — — — — Term extension 3 21 21 — — — Payment modification — — — — — — Bankruptcy — — — 1 8 8 Other — — — — — — Total consumer 3 21 21 1 8 8 Total non-accruing 10 $ 13,030 $ 13,030 4 $ 955 $ 955 Change in recorded investment due to principal paydown at time of modification — $ — $ — — $ — $ — Change in recorded investment due to chargeoffs at time of modification — $ — $ — — $ — $ — The table below represents loans that were modified as TDRs within the previous 12 months and for which there was a payment default for the three and six months ended March 31, 2017 and 2016 , respectively. Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 Number of Loans Recorded Investment Number of Loans Recorded Investment Number of Loans Recorded Investment Number of Loans Recorded Investment (dollars in thousands) Residential real estate — $ — 1 $ — — $ — 1 $ — Commercial real estate — — — — 1 34 — — Commercial non real estate 1 — — — 1 — 1 364 Agriculture — — 2 — — — 2 — Consumer — — — — — — 1 8 Total 1 $ — 3 $ — 2 $ 34 5 $ 372

Allowance for Loan and Lease 33

Allowance for Loan and Lease Losses (Tables)	6 Months Ended
	Mar. 31, 2017
Receivables [Abstract]
Summary of allowances for loan and lease losses	The following tables present the Company’s allowance for loan and lease losses roll forward for the three and six months ended March 31, 2017 and 2016 : Three Months Ended March 31, 2017 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total (dollars in thousands) Beginning balance January 1, 2017 $ 6,786 $ 16,623 $ 13,443 $ 28,519 $ 340 $ 1,056 $ 66,767 Charge-offs (117 ) (1,824 ) (1,734 ) (4,554 ) (31 ) (819 ) (9,079 ) Recoveries 56 286 121 118 15 392 988 Provision 210 2,096 119 2,237 47 351 5,060 Improvement of ASC 310-30 loans (866 ) (185 ) — — — — (1,051 ) Ending balance March 31, 2017 $ 6,069 $ 16,996 $ 11,949 $ 26,320 $ 371 $ 980 $ 62,685 Three Months Ended March 31, 2016 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total (dollars in thousands) Beginning balance January 1, 2016 $ 7,798 $ 19,405 $ 17,160 $ 15,473 $ 341 $ 951 $ 61,128 Charge-offs (506 ) (744 ) (212 ) (1,113 ) (98 ) (597 ) (3,270 ) Recoveries 295 409 235 77 45 367 1,428 Provision 1,218 1,893 (4,552 ) 3,886 48 206 2,699 Improvement of ASC 310-30 loans (9 ) (59 ) — — — — (68 ) Ending balance March 31, 2016 $ 8,796 $ 20,904 $ 12,631 $ 18,323 $ 336 $ 927 $ 61,917 Six Months Ended March 31, 2017 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total (dollars in thousands) Beginning balance October 1, 2016 $ 7,106 $ 17,946 $ 12,990 $ 25,115 $ 438 $ 1,047 $ 64,642 Charge-offs (267 ) (1,824 ) (3,693 ) (7,420 ) (110 ) (1,317 ) (14,631 ) Recoveries 262 385 219 144 30 576 1,616 Provision (140 ) 549 2,433 8,481 13 674 12,010 Improvement of ASC 310-30 loans (892 ) (60 ) — — — — (952 ) Ending balance March 31, 2017 $ 6,069 $ 16,996 $ 11,949 $ 26,320 $ 371 $ 980 $ 62,685 Six Months Ended March 31, 2016 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total (dollars in thousands) Beginning balance October 1, 2015 $ 8,025 $ 18,014 $ 15,996 $ 13,952 $ 348 $ 865 $ 57,200 Charge-offs (702 ) (772 ) (257 ) (1,124 ) (146 ) (997 ) (3,998 ) Recoveries 339 491 639 124 70 532 2,195 Provision 1,240 3,260 (3,677 ) 5,371 64 527 6,785 Improvement of ASC 310-30 loans (106 ) (89 ) (70 ) — — — (265 ) Ending balance March 31, 2016 $ 8,796 $ 20,904 $ 12,631 $ 18,323 $ 336 $ 927 $ 61,917 The following tables provide details regarding the allowance for loan and lease losses and balance by type of allowance as of March 31, 2017 and September 30, 2016 . These tables are presented net of unamortized discount on acquired loans and excludes loans of $1.06 billion measured at fair value, loans held for sale of $4.9 million , and guaranteed loans of $160.8 million for March 31, 2017 and loans measured at fair value of $1.13 billion , loans held for sale of $12.9 million , and guaranteed loans of $120.0 million for September 30, 2016 . As of March 31, 2017 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total (dollars in thousands) Allowance for loan and lease losses Individually evaluated for impairment $ 3,288 $ 3,601 $ 4,985 $ 10,616 $ 103 $ — $ 22,593 Collectively evaluated for impairment 2,781 12,683 6,964 15,704 268 980 39,380 ASC 310-30 loans — 712 — — — — 712 Total allowance $ 6,069 $ 16,996 $ 11,949 $ 26,320 $ 371 $ 980 $ 62,685 Financing Receivables Individually evaluated for impairment $ 9,383 $ 39,574 $ 45,032 $ 145,233 $ 426 $ — $ 239,648 Collectively evaluated for impairment 886,114 3,383,189 1,082,786 1,662,802 73,011 39,976 7,127,878 ASC 310-30 loans 59,108 39,747 2,753 14,799 752 — 117,159 Loans Outstanding $ 954,605 $ 3,462,510 $ 1,130,571 $ 1,822,834 $ 74,189 $ 39,976 $ 7,484,685 As of September 30, 2016 Residential Real Estate Commercial Real Estate Commercial Agriculture Consumer Other Total (dollars in thousands) Allowance for loan and lease losses Individually evaluated for impairment $ 3,000 $ 3,846 $ 6,475 $ 12,278 $ 87 $ — $ 25,686 Collectively evaluated for impairment 3,199 13,328 6,515 12,837 351 1,047 37,277 ASC 310-30 loans 907 772 — — — — 1,679 Total allowance $ 7,106 $ 17,946 $ 12,990 $ 25,115 $ 438 $ 1,047 $ 64,642 Financing Receivables Individually evaluated for impairment $ 10,364 $ 54,005 $ 49,825 $ 101,840 $ 395 $ — $ 216,429 Collectively evaluated for impairment 918,710 3,249,974 1,079,295 1,721,219 74,301 42,477 7,085,976 ASC 310-30 loans 65,737 44,448 3,196 15,254 896 — 129,531 Loans Outstanding $ 994,811 $ 3,348,427 $ 1,132,316 $ 1,838,313 $ 75,592 $ 42,477 $ 7,431,936

Accounting for Certain Loans 34

Accounting for Certain Loans Acquired with Deteriorated Credit Quality (Tables)	6 Months Ended
	Mar. 31, 2017
Receivables [Abstract]
Schedule of troubled debt restructurings	The re-assessment of purchased credit impaired loans resulted in the following changes in the accretable yield during the three and six months ended March 31, 2017 and 2016 : Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands) Balance at beginning of period $ 39,758 $ 41,882 $ 38,124 $ 44,489 Accretion (3,040 ) (2,261 ) (5,978 ) (4,590 ) Reclassification from (to) nonaccretable difference 1,987 222 6,559 (56 ) Balance at end of period $ 38,705 $ 39,843 $ 38,705 $ 39,843
Schedule of impaired loans	The average recorded investment on impaired loans and interest income recognized on impaired loans for the three and six months ended March 31, 2017 and 2016 , respectively, are as follows: Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status (dollars in thousands) Residential real estate $ 9,565 $ 126 $ 12,124 $ 290 $ 9,831 $ 240 $ 12,204 $ 439 Commercial real estate 44,807 545 83,642 2,004 47,873 1,215 78,345 3,473 Commercial non real estate 46,304 358 40,450 766 47,477 780 48,798 1,122 Agriculture 128,919 1,326 109,473 3,256 119,892 3,193 91,013 5,695 Consumer 389 12 308 25 391 27 282 42 Total $ 229,984 $ 2,367 $ 245,997 $ 6,341 $ 225,464 $ 5,455 $ 230,642 $ 10,771 The following table presents the Company’s impaired loans. This table excludes loans covered by FDIC loss sharing agreements: March 31, 2017 September 30, 2016 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance Related Allowance Impaired loans: (dollars in thousands) With an allowance recorded: Residential real estate $ 6,243 $ 6,916 $ 3,288 $ 6,244 $ 6,886 $ 3,000 Commercial real estate 25,935 30,199 3,601 29,965 32,349 3,846 Commercial non real estate 27,195 28,537 4,985 34,526 35,283 6,475 Agriculture 83,940 95,814 10,616 71,501 80,842 12,278 Consumer 421 433 103 383 393 87 Total impaired loans with an allowance recorded 143,734 161,899 22,593 142,619 155,753 25,686 With no allowance recorded: Residential real estate 3,140 4,830 — 4,120 5,807 — Commercial real estate 13,639 14,295 — 24,040 24,660 — Commercial non real estate 17,837 22,317 — 15,299 16,469 — Agriculture 61,293 63,326 — 30,339 31,907 — Consumer 5 5 — 12 12 — Total impaired loans with no allowance recorded 95,914 104,773 — 73,810 78,855 — Total impaired loans $ 239,648 $ 266,672 $ 22,593 $ 216,429 $ 234,608 $ 25,686 The following table provides purchased credit impaired loans at March 31, 2017 and September 30, 2016 : March 31, 2017 September 30, 2016 Outstanding Balance 1 Recorded Investment 2 Carrying 3 Outstanding Balance 1 Recorded Investment 2 Carrying 3 (dollars in thousands) Residential real estate $ 69,261 $ 59,108 $ 59,108 $ 76,696 $ 65,737 $ 64,830 Commercial real estate 123,321 39,747 39,035 129,615 44,448 43,676 Commercial non real estate 11,361 2,753 2,753 11,588 3,196 3,196 Agriculture 18,474 14,799 14,799 19,174 15,254 15,254 Consumer 892 752 752 1,033 896 896 Total lending $ 223,309 $ 117,159 $ 116,447 $ 238,106 $ 129,531 $ 127,852 1 Represents the legal balance of ASC 310-30 loans. 2 Represents the book balance of ASC 310-30 loans. 3 Represents the book balance of ASC 310-30 loans net of the related allowance for loan and lease losses.

FDIC Indemnification Asset (Tab

FDIC Indemnification Asset (Tables)	6 Months Ended
	Mar. 31, 2017
Banking and Thrift [Abstract]
Summary of FDIC indemnification asset activity	The following table represents a summary of the activity related to the FDIC indemnification asset for the three and six months ended March 31, 2017 and 2016 : Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands) Balance at beginning of period $ 9,887 $ 13,185 $ 10,777 $ 14,722 Amortization (1,114 ) (895 ) (1,981 ) (1,927 ) Changes in expected reimbursements from FDIC for changes in expected credit losses (133 ) 1 (105 ) (127 ) Changes in reimbursable expenses (299 ) (78 ) (538 ) (427 ) Reimbursements of covered losses to the FDIC 30 662 218 634 Balance at end of period $ 8,371 $ 12,875 $ 8,371 $ 12,875

Derivative Financial Instrume36

Derivative Financial Instruments (Tables)	6 Months Ended
	Mar. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of derivative positions, notional amounts and estimated fair values	The following table summarizes the notional amounts and estimated fair values of the Company’s derivative instruments at March 31, 2017 and September 30, 2016 : March 31, 2017 Notional Amount Balance Sheet Location Positive Fair Value Negative Fair Value Derivatives not designated as hedging instruments: (dollars in thousands) Interest rate swaps $ 1,049,701 Liabilities $ 7,945 $ (20,466 ) Mortgage loan commitments 33,561 Assets 53 — Mortgage loan forward sale contracts 36,396 Liabilities — (53 ) September 30, 2016 Notional Amount Balance Sheet Location Positive Fair Value Negative Fair Value Derivatives not designated as hedging instruments: (dollars in thousands) Interest rate swaps $ 1,055,822 Liabilities $ 525 $ (81,974 ) Mortgage loan commitments 52,333 Assets 66 — Mortgage loan forward sale contracts 60,529 Liabilities — (66 )
Schedule of derivative instruments, effect on other comprehensive income	The effect of derivatives on the consolidated statements of comprehensive income for the three and six months ended March 31, 2017 and 2016 was as follows: Amount of Gain (Loss) Recognized in Income Three Months Ended Six Months Ended Location of Gain (Loss) Recognized in Income March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 Derivatives not designated as hedging instruments: (dollars in thousands) Interest rate swaps Noninterest income $ 1,592 $ (40,893 ) $ 60,568 $ (31,454 ) Mortgage loan commitments Noninterest income 158 76 53 52 Mortgage loan forward sale contracts Noninterest income (158 ) (76 ) (53 ) (52 )
Summary of offsetting assets	The following tables present the Company's gross derivative financial assets and liabilities at March 31, 2017 and September 30, 2016 , and the related impact of enforceable master netting agreements and cash collateral, where applicable: Gross Amount Net Amount Presented in Consolidated Balance Sheets Held/Pledged Financial Instruments 1 Net March 31, 2017 (dollars in thousands) Derivative financial assets: Derivatives subject to master netting arrangement or similar arrangement $ 7,945 $ (7,945 ) $ — $ — $ — Derivative financial liabilities: Derivatives subject to master netting arrangement or similar arrangement (20,466 ) 7,945 (12,521 ) — (12,521 ) Total derivative financial liabilities $ (12,521 ) $ — $ (12,521 ) $ — $ (12,521 ) 1 The actual amount of collateral exceeds the fair value exposure, at the individual counterparty level, as of the date presented. Gross Amount Net Amount Presented in Consolidated Balance Sheets Held/Pledged Financial Instruments 1 Net September 30, 2016 (dollars in thousands) Derivative financial assets: Derivatives subject to master netting arrangement or similar arrangement $ 525 $ (525 ) $ — $ — $ — Derivative financial liabilities: Derivatives subject to master netting arrangement or similar arrangement (81,974 ) 525 (81,449 ) 81,449 — Total derivative financial liabilities $ (81,449 ) $ — $ (81,449 ) $ 81,449 $ — 1 The actual amount of collateral exceeds the fair value exposure, at the individual counterparty level, as of the date presented.
Summary of offsetting liabilities	The following tables present the Company's gross derivative financial assets and liabilities at March 31, 2017 and September 30, 2016 , and the related impact of enforceable master netting agreements and cash collateral, where applicable: Gross Amount Net Amount Presented in Consolidated Balance Sheets Held/Pledged Financial Instruments 1 Net March 31, 2017 (dollars in thousands) Derivative financial assets: Derivatives subject to master netting arrangement or similar arrangement $ 7,945 $ (7,945 ) $ — $ — $ — Derivative financial liabilities: Derivatives subject to master netting arrangement or similar arrangement (20,466 ) 7,945 (12,521 ) — (12,521 ) Total derivative financial liabilities $ (12,521 ) $ — $ (12,521 ) $ — $ (12,521 ) 1 The actual amount of collateral exceeds the fair value exposure, at the individual counterparty level, as of the date presented. Gross Amount Net Amount Presented in Consolidated Balance Sheets Held/Pledged Financial Instruments 1 Net September 30, 2016 (dollars in thousands) Derivative financial assets: Derivatives subject to master netting arrangement or similar arrangement $ 525 $ (525 ) $ — $ — $ — Derivative financial liabilities: Derivatives subject to master netting arrangement or similar arrangement (81,974 ) 525 (81,449 ) 81,449 — Total derivative financial liabilities $ (81,449 ) $ — $ (81,449 ) $ 81,449 $ — 1 The actual amount of collateral exceeds the fair value exposure, at the individual counterparty level, as of the date presented.

The Fair Value Option For Cer37

The Fair Value Option For Certain Loans (Tables)	6 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Summary of the fair value option	Changes in fair value for items for which the fair value option has been elected and the line items in which these changes are reported within the consolidated statements of comprehensive income are as follows for the three and six months ended March 31, 2017 and 2016 : Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 Noninterest Income Total Changes in Fair Value Noninterest Income Total Changes in Fair Value Noninterest Income Total Changes in Fair Value Noninterest Income Total Changes in Fair Value (dollars in thousands) Long-term loans and written loan commitments $ (5,216 ) $ (5,216 ) $ 35,955 $ 35,955 $ (69,218 ) $ (69,218 ) $ 21,054 $ 21,054

Core Deposits and Other Intan38

Core Deposits and Other Intangibles (Tables)	6 Months Ended
	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of finite-lived intangible assets	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 A summary of intangible assets subject to amortization is as follows: Core Deposit Intangible Brand Customer Relationships Intangible Other Total As of March 31, 2017 (dollars in thousands) Gross carrying amount $ 67,018 $ 8,464 $ 16,089 $ 538 $ 92,109 Accumulated amortization (60,615 ) (4,982 ) (16,089 ) (80 ) (81,766 ) Net intangible assets $ 6,403 $ 3,482 $ — $ 458 $ 10,343 As of September 30, 2016 Gross carrying amount $ 67,018 $ 8,464 $ 16,089 $ 538 $ 92,109 Accumulated amortization (59,842 ) (4,700 ) (15,800 ) (35 ) (80,377 ) Net intangible assets $ 7,176 $ 3,764 $ 289 $ 503 $ 11,732
Schedule of estimated amortization expense of intangible assets	Estimated amortization expense of intangible assets in subsequent fiscal years is as follows: Amount (dollars in thousands) Remaining in 2017 $ 952 2018 1,614 2019 1,489 2020 1,363 2021 1,267 2022 and thereafter 3,658 Total $ 10,343

Loan Servicing Rights (Tables)

Loan Servicing Rights (Tables)	6 Months Ended
	Mar. 31, 2017
Transfers and Servicing [Abstract]
Schedule of loan servicing rights and valuation allowance activity	The following table is the activity for loan servicing rights and the related valuation allowance for the three and six months ended March 31, 2017 and 2016 : Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands) Loan servicing rights Beginning of period $ 5,286 $ — $ 5,794 $ — Additions — — — — Amortization 1 (380 ) — (888 ) — End of period $ 4,906 $ — $ 4,906 $ — Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands) Valuation allowance Beginning of period $ (8 ) $ — $ (13 ) $ — (Additions) / reductions 1 5 — 10 — End of period $ (3 ) $ — $ (3 ) $ — Loan servicing rights, net $ 4,903 $ — $ 4,903 $ — Servicing fees received $ 525 $ — $ 1,073 $ — Balance of loans serviced at: Beginning of period 823,375 — 868,865 — End of period 792,779 — 792,779 — 1 Changes to carrying amounts are reported net of loan servicing income on the consolidated statements of comprehensive income for the periods presented.

Securities Sold Under Agreeme40

Securities Sold Under Agreements to Repurchase (Tables)	6 Months Ended
	Mar. 31, 2017
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Schedule of repurchases agreements	The following tables present the gross obligation by the class of collateral pledged and the remaining contractual maturity of the agreements at March 31, 2017 and September 30, 2016 . March 31, 2017 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater than 90 Days Total Repurchase agreements (dollars in thousands) Municipal securities $ 2,542 $ — $ — $ — $ 2,542 Mortgage-backed securities 121,930 — — — 121,930 Total repurchase agreements $ 124,472 $ — $ — $ — $ 124,472 September 30, 2016 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater than 90 Days Total Repurchase agreements (dollars in thousands) Municipal securities $ — $ — $ — $ — $ — Mortgage-backed securities 138,744 — — 2,944 141,688 Total repurchase agreements $ 138,744 $ — $ — $ 2,944 $ 141,688

FHLB Advances and Other Borro41

FHLB Advances and Other Borrowings (Tables)	6 Months Ended
	Mar. 31, 2017
Federal Home Loan Banks [Abstract]
Schedule of FHLB advances and other borrowings	FHLB advances and other borrowings consist of the following at March 31, 2017 and September 30, 2016 : March 31, 2017 September 30, 2016 (dollars in thousands) Notes payable to Federal Home Loan Bank (FHLB), interest rates from 0.81% to 3.66% and maturity dates from May 2017 to July 2023, collateralized by real estate loans and FHLB stock, with various call dates at the option of the FHLB $ 246,000 $ 640,000 Federal Home Loan Bank fed funds advance, interest rate of 1.06%, maturity date of September 2017 17,000 231,000 Other 1,600 — Total 264,600 871,000 Fair value adjustment 1 24 37 Total FHLB advances and other borrowings $ 264,624 $ 871,037 1 Adjustment reflects the fair value adjustments related to the FHLB advances and notes payable assumed as part of the HF Financial acquisition.
Schedule of FHLB advances and other borrowings by maturity date	As of March 31, 2017 , FHLB advances and other borrowings are due or callable (whichever is earlier) in subsequent fiscal years as follows: Amount (dollars in thousands) Remaining in 2017 $ 118,600 2018 31,000 2019 — 2020 — 2021 — 2022 and thereafter 115,000 Total $ 264,600

Subordinated Debentures and S42

Subordinated Debentures and Subordinated Notes Payable (Tables)	6 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Summary of subordinated debentures and subordinated notes payable	Subordinated debentures and subordinated notes payable are summarized as follows: March 31, 2017 September 30, 2016 Amount Outstanding Common Shares Held in Other Assets Amount Outstanding Common Shares Held in Other Assets (dollars in thousands) Junior subordinated debentures payable to nonconsolidated 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 10,310 310 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 80,920 $ 2,520 Less: fair value adjustment 1 (2,455 ) (3,765 ) Total junior subordinated debentures payable, net of fair value adjustment 73,465 77,155 Subordinated notes payable Fixed to floating rate, 4.875% per annum 35,000 35,000 Less: unamortized debt issuance costs (245 ) (282 ) Total subordinated notes payable 34,755 34,718 Total subordinated debentures and subordinated notes payable $ 108,220 $ 111,873 1 Adjustment reflects the fair value adjustments related to the junior subordinated deferrable interest debentures assumed as part of the HF Financial acquisition.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	6 Months Ended
	Mar. 31, 2017
Compensation and Retirement Disclosure [Abstract]
Summary of the components of net periodic benefit cost	Information relative to the components of net periodic benefit cost measured at/or for the three and six months ended March 31, 2017 and 2016 for the defined benefit plan is presented below: Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands) Net periodic benefit cost Service cost $ 12 $ — $ 24 $ — Interest cost 56 — 112 — Expected return on plan assets (64 ) — (128 ) — Amortization of prior losses 62 — 124 — Net periodic benefit cost $ 66 $ — $ 132 $ —

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of restricted share and performance-based stock award activity	The following is a summary of the Plans’ restricted share and performance-based stock award activity as of March 31, 2017 and September 30, 2016 : March 31, 2017 September 30, 2016 Restricted Shares Common Weighted-Average Grant Date Fair Value Common Weighted-Average Grant Date Fair Value Restricted shares, beginning of fiscal year 160,335 $ 26.89 80,446 $ 18.18 Granted 89,135 39.36 113,543 30.95 Vested and issued (67,213 ) 27.00 (25,729 ) 18.11 Forfeited (1,868 ) 30.00 (7,925 ) 25.09 Canceled — — — — Restricted shares, end of period 180,389 $ 32.98 160,335 $ 26.89 Vested, but not issuable at end of period 32,759 $ 30.53 24,480 $ 26.14 Performance Shares Performance shares, beginning of fiscal year 236,185 $ 20.28 211,026 $ 18.00 Granted 40,204 39.43 43,371 30.78 Vested and issued — — (55 ) 18.00 Forfeited (3,158 ) 20.93 (18,157 ) 18.83 Canceled — — — — Performance shares, end of period 273,231 $ 23.09 236,185 $ 20.28

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of fair value measurements of assets and liabilities	The following table presents the fair value measurements of assets and liabilities recognized in the accompanying consolidated balance sheets measured at fair value on a recurring basis and the level within the fair value hierarchy in which the fair value measurements fall at March 31, 2017 and September 30, 2016 : Fair Value Level 1 Level 2 Level 3 (dollars in thousands) As of March 31, 2017 U.S. Treasury securities $ 228,710 $ 228,710 $ — $ — Mortgage-backed securities 1,051,093 — 1,051,093 — States and political subdivision securities 70,061 — 68,837 1,224 Corporate debt securities — — — — Other 1,029 — 1,029 — Total securities available for sale $ 1,350,893 $ 228,710 $ 1,120,959 $ 1,224 Derivatives-assets $ 53 $ 53 $ — Derivatives-liabilities 12,574 — 12,574 — Fair value loans and written loan commitments 1,056,155 — 1,056,155 — Fair Value Level 1 Level 2 Level 3 (dollars in thousands) As of September 30, 2016 U.S. Treasury securities $ 230,980 $ 230,980 $ — $ — Mortgage-backed securities 1,024,838 — 1,024,838 — States and political subdivision securities 55,484 — 54,169 1,315 Corporate debt securities 5,022 — 5,022 — Other 1,062 — 1,062 — Total securities available for sale $ 1,317,386 $ 230,980 $ 1,085,091 $ 1,315 Derivatives-assets $ 66 $ — $ 66 $ — Derivatives-liabilities 81,515 — 81,515 — Fair value loans and written loan commitments 1,131,111 — 1,131,111 —
Schedule of changes in Level 3 financial instruments	The following table presents the changes in Level 3 financial instruments for the three and six months ended March 31, 2017 and 2016 : Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands) Balance, beginning of period $ 1,224 $ 1,458 $ 1,315 $ 1,835 Principal paydown — — (91 ) (77 ) Realized loss on securities — — — (300 ) Balance, end of period $ 1,224 $ 1,458 $ 1,224 $ 1,458
Summary of mortgage loans held-for-sale, fair value measurement	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 March 31, 2017 and September 30, 2016 : Fair Value Level 1 Level 2 Level 3 (dollars in thousands) As of March 31, 2017 Other real estate owned $ 3,071 $ — $ — $ 3,071 Impaired loans 217,055 — — 217,055 Loans held for sale, at lower of cost or fair value 4,902 — 4,902 — Loan servicing rights 4,903 — — 4,903 Property held for sale 5,258 — — 5,258 As of September 30, 2016 Other real estate owned $ 6,911 $ — $ — $ 6,911 Impaired loans 190,743 — — 190,743 Loans held for sale, at lower of cost or fair value 12,918 — 12,918 — Loan servicing rights 5,781 — — 5,781 Property held for sale 8,112 — — 8,112
Summary of valuation techniques and significant unobservable inputs used to measure Level 3 fair value measurements	The valuation techniques and significant unobservable inputs used to measure Level 3 fair value measurements at March 31, 2017 were as follows: Fair Value of Assets / (Liabilities) at March 31, 2017 Valuation Unobservable Range Weighted (dollars in thousands) Other real estate owned $ 3,071 Appraisal value Property specific adjustment N/A N/A Impaired loans 217,055 Appraisal value Property specific adjustment N/A N/A Loan servicing rights 4,903 Discounted cash flows Constant prepayment rate 9.0 - 21.0% 12.1% Property held for sale 5,258 Appraisal value Property specific adjustment N/A N/A
Schedule of fair values for balance sheet instruments	Fair values for balance sheet instruments as of March 31, 2017 and September 30, 2016 , are as follows: March 31, 2017 September 30, 2016 Level in Fair Value Hierarchy Carrying Amount Fair Carrying Amount Fair (dollars in thousands) Assets Cash and cash equivalents Level 1 $ 335,929 $ 335,929 $ 524,611 $ 524,611 Loans, net excluding fair valued loans and loans held for sale Level 3 7,573,684 7,506,331 7,473,973 7,433,851 Accrued interest receivable Level 2 43,690 43,690 49,531 49,531 Cash surrender value of life insurance policies Level 2 29,188 29,188 29,166 29,166 Federal Home Loan Bank stock Level 2 22,514 22,514 47,025 47,025 Liabilities Deposits Level 2 $ 9,091,918 $ 9,092,262 $ 8,604,790 $ 8,603,708 FHLB advances and other borrowings Level 2 264,624 265,315 871,037 874,763 Securities sold under repurchase agreements Level 2 124,472 124,472 141,688 141,688 Accrued interest payable Level 2 3,983 3,983 4,074 4,074 Subordinated debentures and subordinated notes payable Level 2 108,220 108,151 111,873 112,826

Earnings per Share (Tables)

Earnings per Share (Tables)	6 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Schedule of basic and diluted earnings per share	The following information was used in the computation of basic and diluted earnings per share (EPS) for the three and six months ended March 31, 2017 and 2016 : Three Months Ended Six Months Ended March 31, 2017 March 31, 2016 March 31, 2017 March 31, 2016 (dollars in thousands, except per share data) Net income $ 35,162 $ 30,674 $ 72,065 $ 61,135 Weighted average common shares outstanding 58,788,802 55,269,557 58,769,662 55,261,634 Dilutive effect of stock based compensation 284,867 139,319 263,125 139,530 Weighted average common shares outstanding for diluted earnings per share calculation 59,073,669 55,408,876 59,032,787 55,401,164 Basic earnings per share $ 0.60 $ 0.56 $ 1.23 $ 1.11 Diluted earnings per share $ 0.60 $ 0.55 $ 1.22 $ 1.10

Nature of Operations and Summ47

Nature of Operations and Summary of Significant Policies - Narrative (Details)	Apr. 27, 2017$ / shares	Mar. 31, 2017USD ($)$ / shares	Mar. 31, 2016USD ($)$ / shares	Mar. 31, 2017USD ($)portfolio_class$ / shares	Mar. 31, 2016USD ($)$ / shares	Sep. 30, 2016USD ($)	Dec. 31, 2010agreement	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Sep. 30, 2015USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maturity period of loans and loan commitments				5 years
Number of portfolio classes | portfolio_class				6
FDIC Indemnification, number of loss share agreements entered | agreement							2
FDIC Indemnification, expected reimbursement rate (as a percent)						80.00%
FDIC Clawback Liability, payment period following termination or maturity of agreement						45 days
Impairment related to goodwill		$ 0	$ 0	$ 0	$ 0
Impairment of intangible assets		0	0	0	0
Loan servicing rights, valuation allowance		$ (3,000)	$ 0	$ (3,000)	$ 0	$ (13,000)		$ (8,000)	$ 0	$ 0
Common stock dividends declared (in dollars per share) | $ / shares		$ 0.17	$ 0.14	$ 0.34	$ 0.28
Subsequent event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Common stock dividends declared (in dollars per share) | $ / shares	$ 0.2
Residential loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
FDIC Indemnification, number of loss share agreements entered | agreement							1
Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maturity period of loans and loan commitments				5 years
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maturity period of loans and loan commitments				15 years

Nature of Operations and Summ48

Nature of Operations and Summary of Significant Policies - Schedule of Amortization Methods Used and Useful Lives (Details)	6 Months Ended
	Mar. 31, 2017
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 Intangible | Minimum
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life	1 year 3 months
Other Intangible | Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life	9 years 4 months

Acquisition Activity - Narrativ

Acquisition Activity - Narrative (Details)	May 16, 2016USD ($)bank$ / sharesshares	Mar. 31, 2017USD ($)	Sep. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)
Business Acquisition [Line Items]
Goodwill		$ 739,023,000	$ 739,023,000		$ 739,023,000
Acquisition expenses		0		$ 771,000	710,000	$ 771,000
HF Financial Corporation
Business Acquisition [Line Items]
Percentage of voting interests acquired (as a percent)	100.00%
Equity interest issued per share as part of merger (in shares) | shares	0.65
Consideration paid as part of merger (in dollars per share) | $ / shares	$ 19.50
Percentage of outstanding shares exchanged for cash as part of merger (as a percent)	24.29%
Percentage of outstanding shares exchanged for common stock as part of merger (as a percent)	75.71%
Net purchase price	$ 141,965,000
Goodwill	$ 41,216,000
Number of bank locations acquired | bank	23
Goodwill expected to be tax deductible	$ 0
Intangible assets	14,500,000
Increase in goodwill			$ 600,000
Acquisition expenses		$ 0		$ 800,000	$ 700,000	$ 800,000
Net loans acquired	863,741,000
Acquired loans, estimated discount	$ 28,500,000
Acquired loans, percentage of estimated discount (as a percent)	3.30%
HF Financial Corporation | Acquired receivables subject to ASC 310-30
Business Acquisition [Line Items]
Net loans acquired	$ 65,400,000

Acquisition Activity - Schedule

Acquisition Activity - Schedule of Consideration (Details) - USD ($) $ in Thousands	May 16, 2016	Mar. 31, 2017	Sep. 30, 2016
Non-equity consideration:
Goodwill		$ 739,023	$ 739,023
HF Financial Corporation
Equity consideration:
Common stock issued (in shares)	3,448,119
Common stock issued	$ 107,478
Non-equity consideration:
Cash	34,487
Total consideration paid	141,965
Fair value of net assets acquired including identifiable intangible assets	100,749
Goodwill	$ 41,216

Acquisition Activity - Schedu51

Acquisition Activity - Schedule of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	May 16, 2016	Mar. 31, 2017	Sep. 30, 2016
Liabilities assumed:
Goodwill		$ 739,023	$ 739,023
HF Financial Corporation
Identifiable assets acquired:
Cash and cash equivalents	$ 18,818
Investment securities	165,052
Loans	863,741
Premises and equipment	19,220
Accrued interest receivable	4,117
Other repossessed property	4
Intangible assets	7,877
Loan servicing rights	6,573
Other assets	36,076
Total identifiable assets acquired	1,121,478
Liabilities assumed:
Deposits	863,121
FHLB advances and other borrowings	115,881
Subordinated debentures	21,110
Other liabilities	20,617
Total liabilities assumed	1,020,729
Fair value of net identifiable assets acquired	100,749
Net purchase price	141,965
Goodwill	$ 41,216

Acquisition Activity - Schedu52

Acquisition Activity - Schedule of Pro Forma Information (Details) - HF Financial Corporation - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Business Acquisition [Line Items]
Net interest income	$ 97,399	$ 95,940	$ 196,042	$ 191,383
Net income	$ 35,162	$ 32,743	$ 72,065	$ 64,682
Basic earnings per share (in USD per share)	$ 0.60	$ 0.59	$ 1.23	$ 1.17
Fully diluted earnings per share (in USD per share)	$ 0.60	$ 0.59	$ 1.22	$ 1.17

Acquisition Activity - Schedu53

Acquisition Activity - Schedule of Total Contractually Required Principal and Interest (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	May 16, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015
Business Acquisition [Line Items]
Accretable yield	$ (38,705)	$ (39,758)	$ (38,124)		$ (39,843)	$ (41,882)	$ (44,489)
HF Financial Corporation | Acquired receivables subject to ASC 310-30
Business Acquisition [Line Items]
Contractually required principal and interest				$ 83,710
Non-accretable difference				(28,516)
Cash flows expected to be collected				55,194
Accretable yield				(3,662)
Total purchased credit impaired loans acquired				$ 51,532

Acquisition Activity - Schedu54

Acquisition Activity - Schedule of Acquired Loans (Details) - HF Financial Corporation $ in Thousands	May 16, 2016USD ($)
Business Acquisition [Line Items]
Fair Value of Acquired Loans at Acquisition Date	$ 812,209
Gross Contractual Amounts Receivable at Acquisition Date	998,255
Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected	9,572
Acquired receivables subject to ASC 310-30
Business Acquisition [Line Items]
Fair Value of Acquired Loans at Acquisition Date	51,532
Gross Contractual Amounts Receivable at Acquisition Date	83,710
Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected	$ 28,516

Securities Available for Sale -

Securities Available for Sale - Narrative (Details)	3 Months Ended		6 Months Ended
	Mar. 31, 2017USD ($)security	Mar. 31, 2016USD ($)	Mar. 31, 2017USD ($)security	Mar. 31, 2016USD ($)security	Sep. 30, 2016USD ($)security
Investments, Debt and Equity Securities [Abstract]
Proceeds from sales of securities available for sale	$ 5,000,000	$ 25,000,000	$ 5,042,000	$ 24,996,000
Available-for-sale securities, gross realized gains	0	0	0
Available-for-sale securities, gross realized losses	0	0	0	0
Other than temporary impairment losses recognized in earnings	0	$ 0	0	$ 400,000
Number of securities written off | security				2
Securities pledged as collateral	$ 836,500,000		$ 836,500,000		$ 971,300,000
Percentage of investment portfolio in continuous loss position (as a percent)	70.00%		70.00%		25.00%
Number of securities in an unrealized loss position (securities) | security	260		260		110

Securities Available for Sale56

Securities Available for Sale - Schedule of Amortized Cost and Fair Value of Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Amortized Cost	$ 1,361,649	$ 1,308,445
Gross Unrealized Gains	2,093	11,027
Gross Unrealized Losses	(12,849)	(2,086)
Estimated Fair Value	1,350,893	1,317,386
U.S. Treasury securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Amortized Cost	227,521	227,007
Gross Unrealized Gains	1,195	3,973
Gross Unrealized Losses	(6)	0
Estimated Fair Value	228,710	230,980
Mortgage-backed securities | Government National Mortgage Association
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Amortized Cost	592,330	664,529
Gross Unrealized Gains	419	3,172
Gross Unrealized Losses	(7,654)	(1,922)
Estimated Fair Value	585,095	665,779
Mortgage-backed securities | Federal National Mortgage Association
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Amortized Cost	271,184	212,452
Gross Unrealized Gains	40	1,324
Gross Unrealized Losses	(2,356)	0
Estimated Fair Value	268,868	213,776
Mortgage-backed securities | Small Business Assistance Program
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Amortized Cost	198,313	142,921
Gross Unrealized Gains	342	2,362
Gross Unrealized Losses	(1,525)	0
Estimated Fair Value	197,130	145,283
States and political subdivision securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Amortized Cost	71,288	55,525
Gross Unrealized Gains	81	123
Gross Unrealized Losses	(1,308)	(164)
Estimated Fair Value	70,061	55,484
Corporate debt securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Amortized Cost	0	4,998
Gross Unrealized Gains	0	24
Gross Unrealized Losses	0	0
Estimated Fair Value	0	5,022
Other
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Amortized Cost	1,013	1,013
Gross Unrealized Gains	16	49
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 1,029	$ 1,062

Securities Available for Sale57

Securities Available for Sale - Schedule of Amortized Cost and Fair Value of Investments by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Amortized Cost
Due in one year or less	$ 30,263	$ 3,706
Due after one year through five years	248,718	265,253
Due after five years through ten years	19,706	18,449
Due after ten years	122	122
Amortized Cost	298,809	287,530
Estimated Fair Value
Due in one year or less	30,307	3,709
Due after one year through five years	249,230	269,242
Due after five years through ten years	19,112	18,413
Due after ten years	122	122
Estimated Fair Value	298,771	291,486
Amortized Cost	1,361,649	1,308,445
Estimated Fair Value	1,350,893	1,317,386
Securities without contractual maturities, Amortized Cost	1,013	1,013
Securities without contractual maturities, Fair Value	1,029	1,062
Mortgage-backed securities
Estimated Fair Value
Amortized Cost	1,061,827	1,019,902
Estimated Fair Value	$ 1,051,093	$ 1,024,838

Securities Available for Sale58

Securities Available for Sale - Schedule of Gross Unrealized Losses on Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, Estimated Fair Value	$ 674,737	$ 45,461
12 months or more, Estimated Fair Value	276,282	284,995
Estimated Fair Value	951,019	330,456
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 months, Unrealized Losses	(7,344)	(170)
12 months or more, Unrealized Losses	(5,505)	(1,916)
Unrealized Losses	(12,849)	(2,086)
U.S. Treasury securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, Estimated Fair Value	19,539	0
12 months or more, Estimated Fair Value	0	0
Estimated Fair Value	19,539	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 months, Unrealized Losses	(6)	0
12 months or more, Unrealized Losses	0	0
Unrealized Losses	(6)	0
Mortgage-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, Estimated Fair Value	602,146	17,528
12 months or more, Estimated Fair Value	276,282	284,995
Estimated Fair Value	878,428	302,523
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 months, Unrealized Losses	(6,030)	(6)
12 months or more, Unrealized Losses	(5,505)	(1,916)
Unrealized Losses	(11,535)	(1,922)
States and political subdivision securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, Estimated Fair Value	53,052	27,933
12 months or more, Estimated Fair Value	0	0
Estimated Fair Value	53,052	27,933
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 months, Unrealized Losses	(1,308)	(164)
12 months or more, Unrealized Losses	0	0
Unrealized Losses	$ (1,308)	$ (164)

Securities Available for Sale59

Securities Available for Sale - Schedule of Unrealized Gains (Lossess) on Securities (Details) - Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Beginning balance accumulated other comprehensive income (loss)	$ (7,776)	$ (5,289)	$ 5,534	$ 2,318
Net unrealized holding gain (loss) arising during the period	1,727	16,102	(19,741)	4,187
Reclassification adjustment for net gain (loss) realized in net income	44	24	44	(330)
Net change in unrealized gain (loss) before income taxes	1,771	16,126	(19,697)	3,857
Income tax (expense) benefit	(673)	(6,128)	7,485	(1,466)
Net change in unrealized gain (loss) on securities after taxes	1,098	9,998	(12,212)	2,391
Ending balance accumulated other comprehensive income (loss)	$ (6,678)	$ 4,709	$ (6,678)	$ 4,709

Loans - Narrative (Details)

Loans - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans covered by FDIC loss share agreements	$ 64,681		$ 64,681		$ 73,272
Loan held for sale	4,902		4,902		12,918
Loans and written loan commitments at fair value under the fair value option	1,056,155		1,056,155		1,131,111
Unamortized discount on acquired loans	9,200		9,200		8,600
Loans in process	(100)		(100)		4,700
Loans guaranteed by U.S. Government Agencies	7,484,685		7,484,685		7,431,936
Principal balances of residential real estate loans sold	53,400	$ 50,400	145,100	$ 108,600
Loans greater than 90 days past due and still accruing interest	3,800		3,800		2,000
Valuation adjustments made to repossessed properties	500	500	900	500
Specific reserves included in the allowance for loan losses for TDRs	7,200		7,200		9,300
Troubled debt restructuring, commitments to lend additional funds	0		0		900
Transfers out of troubled debt restructuring status	2,100	$ 0	2,100	$ 4,300
Loans Guaranteed by US Government Authorities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans guaranteed by U.S. Government Agencies	$ 160,800		$ 160,800		$ 120,000

Loans - Schedule of Loans Recei

Loans - Schedule of Loans Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	$ 8,741,339	$ 8,735,918
Less: Unamortized discount on acquired loans	(34,812)	(39,947)
Unearned net deferred fees and costs and loans in process	(9,101)	(13,327)
Net loans	8,697,426	8,682,644
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	971,374	1,020,958
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	3,850,835	3,754,107
Commercial non real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	1,690,149	1,673,166
Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	2,114,287	2,168,937
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	74,718	76,273
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total financing receivables, gross	$ 39,976	$ 42,477

Loans - Schedule of the Company

Loans - Schedule of the Company's Nonaccrual Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans, excluding loans covered under FDIC loss-sharing arrangements	$ 116,055	$ 113,636
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans, excluding loans covered under FDIC loss-sharing arrangements	5,290	5,962
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans, excluding loans covered under FDIC loss-sharing arrangements	13,165	13,870
Commercial non real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans, excluding loans covered under FDIC loss-sharing arrangements	27,273	27,280
Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans, excluding loans covered under FDIC loss-sharing arrangements	70,134	66,301
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans, excluding loans covered under FDIC loss-sharing arrangements	$ 193	$ 223

Loans - Schedule of the Composi

Loans - Schedule of the Composition of the Loan Portfolio by Internal Risk Rating (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	$ 7,585,689	$ 7,491,586
Loans covered by FDIC loss share agreements	64,681	73,272
Total	7,650,370	7,564,858
Pass
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	6,990,975	6,921,071
Watchlist
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	324,457	327,608
Substandard
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	263,716	241,605
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	6,541	1,302
Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	895,160	934,980
Loans covered by FDIC loss share agreements	64,681	73,272
Total	959,841	1,008,252
Residential real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	881,321	919,224
Residential real estate | Watchlist
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	3,962	4,741
Residential real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	9,520	10,885
Residential real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	357	130
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	3,546,453	3,414,758
Loans covered by FDIC loss share agreements	0	0
Total	3,546,453	3,414,758
Commercial real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	3,433,051	3,276,048
Commercial real estate | Watchlist
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	68,585	81,148
Commercial real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	44,298	57,415
Commercial real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	519	147
Commercial non real estate
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	1,192,611	1,173,910
Loans covered by FDIC loss share agreements	0	0
Total	1,192,611	1,173,910
Commercial non real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	1,115,087	1,093,913
Commercial non real estate | Watchlist
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	36,378	37,283
Commercial non real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	35,687	42,319
Commercial non real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	5,459	395
Agriculture
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	1,837,300	1,849,869
Loans covered by FDIC loss share agreements	0	0
Total	1,837,300	1,849,869
Agriculture | Pass
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	1,447,894	1,514,344
Agriculture | Watchlist
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	215,434	204,326
Agriculture | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	173,766	130,569
Agriculture | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	206	630
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	74,189	75,592
Loans covered by FDIC loss share agreements	0	0
Total	74,189	75,592
Consumer | Pass
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	73,646	75,065
Consumer | Watchlist
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	98	110
Consumer | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	445	417
Consumer | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	0	0
Other
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	39,976	42,477
Loans covered by FDIC loss share agreements	0	0
Total	39,976	42,477
Other | Pass
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	39,976	42,477
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

Loans - Schedule of Past Due Lo

Loans - Schedule of Past Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	$ 7,585,689	$ 7,491,586
Loans covered by FDIC loss sharing agreements	64,681	73,272
Total	7,650,370	7,564,858
Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	895,160	934,980
Loans covered by FDIC loss sharing agreements	64,681	73,272
Total	959,841	1,008,252
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	3,546,453	3,414,758
Loans covered by FDIC loss sharing agreements	0	0
Total	3,546,453	3,414,758
Commercial non real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,192,611	1,173,910
Loans covered by FDIC loss sharing agreements	0	0
Total	1,192,611	1,173,910
Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,837,300	1,849,869
Loans covered by FDIC loss sharing agreements	0	0
Total	1,837,300	1,849,869
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	74,189	75,592
Loans covered by FDIC loss sharing agreements	0	0
Total	74,189	75,592
Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	39,976	42,477
Loans covered by FDIC loss sharing agreements	0	0
Total	39,976	42,477
Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	53,365	40,094
Loans covered by FDIC loss sharing agreements	2,650	2,944
Total	56,015	43,038
Past Due | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	5,516	3,439
Past Due | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	5,295	7,469
Past Due | Commercial non real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	19,210	16,697
Past Due | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	23,228	12,232
Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	116	257
Past Due | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	0	0
Past Due | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	14,926	4,364
Loans covered by FDIC loss sharing agreements	1,430	1,404
Total	16,356	5,768
Past Due | 30-59 Days Past Due | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	2,943	828
Past Due | 30-59 Days Past Due | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	386	1,765
Past Due | 30-59 Days Past Due | Commercial non real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	2,118	1,588
Past Due | 30-59 Days Past Due | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	9,408	(26)
Past Due | 30-59 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	71	209
Past Due | 30-59 Days Past Due | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	0	0
Past Due | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	4,364	8,751
Loans covered by FDIC loss sharing agreements	642	1,173
Total	5,006	9,924
Past Due | 60-89 Days Past Due | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	869	548
Past Due | 60-89 Days Past Due | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	0	1,959
Past Due | 60-89 Days Past Due | Commercial non real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	670	5,515
Past Due | 60-89 Days Past Due | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	2,822	709
Past Due | 60-89 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	3	20
Past Due | 60-89 Days Past Due | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	0	0
Past Due | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	34,075	26,979
Loans covered by FDIC loss sharing agreements	578	367
Total	34,653	27,346
Past Due | 90 Days or Greater Past Due | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,704	2,063
Past Due | 90 Days or Greater Past Due | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	4,909	3,745
Past Due | 90 Days or Greater Past Due | Commercial non real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	16,422	9,594
Past Due | 90 Days or Greater Past Due | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	10,998	11,549
Past Due | 90 Days or Greater Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	42	28
Past Due | 90 Days or Greater Past Due | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	0	0
Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	7,532,324	7,451,492
Loans covered by FDIC loss sharing agreements	62,031	70,328
Total	7,594,355	7,521,820
Current | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	889,644	931,541
Current | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	3,541,158	3,407,289
Current | Commercial non real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,173,401	1,157,213
Current | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	1,814,072	1,837,637
Current | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	74,073	75,335
Current | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, net of unamortized discount on acquired loans	$ 39,976	$ 42,477

Loans - Schedule of Impaired Lo

Loans - Schedule of Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2016
With an allowance recorded:
Recorded Investment	$ 143,734		$ 143,734		$ 142,619
Unpaid Principal Balance	161,899		161,899		155,753
Related Allowance	22,593		22,593		25,686
With no allowance recorded:
Recorded Investment	95,914		95,914		73,810
Unpaid Principal Balance	104,773		104,773		78,855
Total Recorded Investment, Impaired Loans	239,648		239,648		216,429
Total Unpaid Principal Balance, Impaired Loans	266,672		266,672		234,608
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	229,984	$ 245,997	225,464	$ 230,642
Interest Income Recognized While on Impaired Status	2,367	6,341	5,455	10,771
Residential real estate
With an allowance recorded:
Recorded Investment	6,243		6,243		6,244
Unpaid Principal Balance	6,916		6,916		6,886
Related Allowance	3,288		3,288		3,000
With no allowance recorded:
Recorded Investment	3,140		3,140		4,120
Unpaid Principal Balance	4,830		4,830		5,807
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	9,565	12,124	9,831	12,204
Interest Income Recognized While on Impaired Status	126	290	240	439
Commercial real estate
With an allowance recorded:
Recorded Investment	25,935		25,935		29,965
Unpaid Principal Balance	30,199		30,199		32,349
Related Allowance	3,601		3,601		3,846
With no allowance recorded:
Recorded Investment	13,639		13,639		24,040
Unpaid Principal Balance	14,295		14,295		24,660
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	44,807	83,642	47,873	78,345
Interest Income Recognized While on Impaired Status	545	2,004	1,215	3,473
Commercial non real estate
With an allowance recorded:
Recorded Investment	27,195		27,195		34,526
Unpaid Principal Balance	28,537		28,537		35,283
Related Allowance	4,985		4,985		6,475
With no allowance recorded:
Recorded Investment	17,837		17,837		15,299
Unpaid Principal Balance	22,317		22,317		16,469
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	46,304	40,450	47,477	48,798
Interest Income Recognized While on Impaired Status	358	766	780	1,122
Agriculture
With an allowance recorded:
Recorded Investment	83,940		83,940		71,501
Unpaid Principal Balance	95,814		95,814		80,842
Related Allowance	10,616		10,616		12,278
With no allowance recorded:
Recorded Investment	61,293		61,293		30,339
Unpaid Principal Balance	63,326		63,326		31,907
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	128,919	109,473	119,892	91,013
Interest Income Recognized While on Impaired Status	1,326	3,256	3,193	5,695
Consumer
With an allowance recorded:
Recorded Investment	421		421		383
Unpaid Principal Balance	433		433		393
Related Allowance	103		103		87
With no allowance recorded:
Recorded Investment	5		5		12
Unpaid Principal Balance	5		5		$ 12
Average recorded investment and interest income recognized on impaired loans:
Average Recorded Investment	389	308	391	282
Interest Income Recognized While on Impaired Status	$ 12	$ 25	$ 27	$ 42

Loans - Summary of Troubled Deb

Loans - Summary of Troubled Debt Restructurings on Accruing and Nonaccrual Financing Receivables (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017USD ($)contract	Mar. 31, 2016USD ($)contract	Mar. 31, 2017USD ($)contract	Mar. 31, 2016USD ($)contract	Sep. 30, 2016USD ($)
Accruing
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 38,655		$ 38,655		$ 46,568
Financing receivable, modifications, number of contracts | contract	4	17	7	28
Financing receivable, modifications, pre-modification recorded investment	$ 8,527	$ 16,612	$ 8,969	$ 40,541
Financing receivable, modifications, post-modification recorded investment	$ 8,527	$ 16,612	$ 8,969	$ 40,541
Change in recorded investment due to principal paydown at time of modification, number of contracts | contract	0	0	0	0
Change in recorded investment due to principal paydown at time of modification, pre-modification	$ 0	$ 0	$ 0	$ 0
Change in recorded investment due to principal paydown at time of modification, post-modification	$ 0	$ 0	$ 0	$ 0
Change in recorded investment due to chargeoffs at time of modification, number of contracts | contract	0	0	0	0
Change in recorded investment due to chargeoffs at time of modification, pre-modification	$ 0	$ 0	$ 0	$ 0
Change in recorded investment due to chargeoffs at time of modification, post-modification	0	$ 0	0	$ 0
Accruing | Residential real estate
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 328		$ 328		370
Financing receivable, modifications, number of contracts | contract	0	0	1	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 9	$ 0
Financing receivable, modifications, post-modification recorded investment	0	$ 0	9	$ 0
Accruing | Commercial real estate
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 5,302		$ 5,302		18,250
Financing receivable, modifications, number of contracts | contract	0	3	0	5
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 6,714	$ 0	$ 8,612
Financing receivable, modifications, post-modification recorded investment	0	$ 6,714	0	$ 8,612
Accruing | Commercial non real estate
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 4,859		$ 4,859		8,102
Financing receivable, modifications, number of contracts | contract	2	5	4	6
Financing receivable, modifications, pre-modification recorded investment	$ 93	$ 3,968	$ 526	$ 4,026
Financing receivable, modifications, post-modification recorded investment	93	$ 3,968	526	$ 4,026
Accruing | Agriculture
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 28,162		$ 28,162		19,823
Financing receivable, modifications, number of contracts | contract	2	9	2	17
Financing receivable, modifications, pre-modification recorded investment	$ 8,434	$ 5,930	$ 8,434	$ 27,903
Financing receivable, modifications, post-modification recorded investment	8,434	$ 5,930	8,434	$ 27,903
Accruing | Consumer
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 4		$ 4		23
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Rate modification | Residential real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Rate modification | Commercial real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Rate modification | Commercial non real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	1	0	1
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 49	$ 0	$ 49
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 49	$ 0	$ 49
Accruing | Rate modification | Agriculture
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Rate modification | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Term extension | Residential real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Term extension | Commercial real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	2
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 1,898
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 1,898
Accruing | Term extension | Commercial non real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	1
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 58
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 58
Accruing | Term extension | Agriculture
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	2	5	2	13
Financing receivable, modifications, pre-modification recorded investment	$ 8,434	$ 4,941	$ 8,434	$ 26,914
Financing receivable, modifications, post-modification recorded investment	$ 8,434	$ 4,941	$ 8,434	$ 26,914
Accruing | Term extension | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Payment modification | Residential real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	1	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 9	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 9	$ 0
Accruing | Payment modification | Commercial real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Payment modification | Commercial non real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	2	1	4	1
Financing receivable, modifications, pre-modification recorded investment	$ 93	$ 70	$ 526	$ 70
Financing receivable, modifications, post-modification recorded investment	$ 93	$ 70	$ 526	$ 70
Accruing | Payment modification | Agriculture
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	4	0	4
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 989	$ 0	$ 989
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 989	$ 0	$ 989
Accruing | Payment modification | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Bankruptcy | Residential real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Bankruptcy | Commercial real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Bankruptcy | Commercial non real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Bankruptcy | Agriculture
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Bankruptcy | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Other | Residential real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Other | Commercial real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	3	0	3
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 6,714	$ 0	$ 6,714
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 6,714	$ 0	$ 6,714
Accruing | Other | Commercial non real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	3	0	3
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 3,849	$ 0	$ 3,849
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 3,849	$ 0	$ 3,849
Accruing | Other | Agriculture
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Accruing | Other | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	0	$ 0	0	$ 0
Nonaccrual
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 43,528		$ 43,528		36,778
Financing receivable, modifications, number of contracts | contract	9	2	10	4
Financing receivable, modifications, pre-modification recorded investment	$ 13,009	$ 372	$ 13,030	$ 955
Financing receivable, modifications, post-modification recorded investment	$ 13,009	$ 372	$ 13,030	$ 955
Change in recorded investment due to principal paydown at time of modification, number of contracts | contract	0	0	0	0
Change in recorded investment due to principal paydown at time of modification, pre-modification	$ 0	$ 0	$ 0	$ 0
Change in recorded investment due to principal paydown at time of modification, post-modification	$ 0	$ 0	$ 0	$ 0
Change in recorded investment due to chargeoffs at time of modification, number of contracts | contract	0	0	0	0
Change in recorded investment due to chargeoffs at time of modification, pre-modification	$ 0	$ 0	$ 0	$ 0
Change in recorded investment due to chargeoffs at time of modification, post-modification	0	$ 0	0	$ 0
Nonaccrual | Residential real estate
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 614		$ 614		937
Financing receivable, modifications, number of contracts | contract	0	0	1	1
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 21	$ 187
Financing receivable, modifications, post-modification recorded investment	0	$ 0	21	$ 187
Nonaccrual | Commercial real estate
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 2,178		$ 2,178		2,356
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	0	$ 0	0	$ 0
Nonaccrual | Commercial non real estate
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 2,033		$ 2,033		4,789
Financing receivable, modifications, number of contracts | contract	0	1	0	2
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 364	$ 0	$ 760
Financing receivable, modifications, post-modification recorded investment	0	$ 364	0	$ 760
Nonaccrual | Agriculture
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 38,674		$ 38,674		28,688
Financing receivable, modifications, number of contracts | contract	6	0	6	0
Financing receivable, modifications, pre-modification recorded investment	$ 12,988	$ 0	$ 12,988	$ 0
Financing receivable, modifications, post-modification recorded investment	12,988	$ 0	12,988	$ 0
Nonaccrual | Consumer
Financing Receivable, Modifications [Line Items]
Recorded value of TDR balance	$ 29		$ 29		$ 8
Financing receivable, modifications, number of contracts | contract	3	1	3	1
Financing receivable, modifications, pre-modification recorded investment	$ 21	$ 8	$ 21	$ 8
Financing receivable, modifications, post-modification recorded investment	$ 21	$ 8	$ 21	$ 8
Nonaccrual | Rate modification | Residential real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Rate modification | Commercial real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Rate modification | Commercial non real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Rate modification | Agriculture
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Rate modification | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Term extension | Residential real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Term extension | Commercial real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Term extension | Commercial non real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Term extension | Agriculture
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	6	0	6	0
Financing receivable, modifications, pre-modification recorded investment	$ 12,988	$ 0	$ 12,988	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 12,988	$ 0	$ 12,988	$ 0
Nonaccrual | Term extension | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	3	0	3	0
Financing receivable, modifications, pre-modification recorded investment	$ 21	$ 0	$ 21	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 21	$ 0	$ 21	$ 0
Nonaccrual | Payment modification | Residential real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	1	1
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 21	$ 187
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 21	$ 187
Nonaccrual | Payment modification | Commercial real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Payment modification | Commercial non real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	1	0	2
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 364	$ 0	$ 760
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 364	$ 0	$ 760
Nonaccrual | Payment modification | Agriculture
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Payment modification | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Bankruptcy | Residential real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Bankruptcy | Commercial real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Bankruptcy | Commercial non real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Bankruptcy | Agriculture
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Bankruptcy | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	1	0	1
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 8	$ 0	$ 8
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 8	$ 0	$ 8
Nonaccrual | Other | Residential real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Other | Commercial real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Other | Commercial non real estate
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Other | Agriculture
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Nonaccrual | Other | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, number of contracts | contract	0	0	0	0
Financing receivable, modifications, pre-modification recorded investment	$ 0	$ 0	$ 0	$ 0
Financing receivable, modifications, post-modification recorded investment	$ 0	$ 0	$ 0	$ 0

Loans - Subsequent Defaults on

Loans - Subsequent Defaults on Modified Loans (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017USD ($)contract	Mar. 31, 2016USD ($)contract	Mar. 31, 2017USD ($)contract	Mar. 31, 2016USD ($)contract
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	1	3	2	5
Recorded Investment | $	$ 0	$ 0	$ 34	$ 372
Residential real estate
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	0	1	0	1
Recorded Investment | $	$ 0	$ 0	$ 0	$ 0
Commercial real estate
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	0	0	1	0
Recorded Investment | $	$ 0	$ 0	$ 34	$ 0
Commercial non real estate
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	1	0	1	1
Recorded Investment | $	$ 0	$ 0	$ 0	$ 364
Agriculture
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	0	2	0	2
Recorded Investment | $	$ 0	$ 0	$ 0	$ 0
Consumer
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	0	0	0	1
Recorded Investment | $	$ 0	$ 0	$ 0	$ 8

Allowance for Loan and Lease 68

Allowance for Loan and Lease Losses - Summary of Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	$ 66,767	$ 61,128	$ 64,642	$ 57,200
Charge-offs	(9,079)	(3,270)	(14,631)	(3,998)
Recoveries	988	1,428	1,616	2,195
Provision	5,060	2,699	12,010	6,785
Improvement of ASC 310-30 loans			(952)	(265)
Allowance for loan losses, ending balance	62,685	61,917	62,685	61,917
Acquired receivables subject to ASC 310-30
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance			1,679
Recoveries	1,100	100	1,000	300
Improvement of ASC 310-30 loans	(1,051)	(68)
Allowance for loan losses, ending balance	712		712
Residential real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	6,786	7,798	7,106	8,025
Charge-offs	(117)	(506)	(267)	(702)
Recoveries	56	295	262	339
Provision	210	1,218	(140)	1,240
Allowance for loan losses, ending balance	6,069	8,796	6,069	8,796
Residential real estate | Acquired receivables subject to ASC 310-30
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance			907
Improvement of ASC 310-30 loans	(866)	(9)	(892)	(106)
Allowance for loan losses, ending balance	0		0
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	16,623	19,405	17,946	18,014
Charge-offs	(1,824)	(744)	(1,824)	(772)
Recoveries	286	409	385	491
Provision	2,096	1,893	549	3,260
Allowance for loan losses, ending balance	16,996	20,904	16,996	20,904
Commercial real estate | Acquired receivables subject to ASC 310-30
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance			772
Improvement of ASC 310-30 loans	(185)	(59)	(60)	(89)
Allowance for loan losses, ending balance	712		712
Commercial non real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	13,443	17,160	12,990	15,996
Charge-offs	(1,734)	(212)	(3,693)	(257)
Recoveries	121	235	219	639
Provision	119	(4,552)	2,433	(3,677)
Allowance for loan losses, ending balance	11,949	12,631	11,949	12,631
Commercial non real estate | Acquired receivables subject to ASC 310-30
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance			0
Improvement of ASC 310-30 loans	0	0	0	(70)
Allowance for loan losses, ending balance	0		0
Agriculture
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	28,519	15,473	25,115	13,952
Charge-offs	(4,554)	(1,113)	(7,420)	(1,124)
Recoveries	118	77	144	124
Provision	2,237	3,886	8,481	5,371
Allowance for loan losses, ending balance	26,320	18,323	26,320	18,323
Agriculture | Acquired receivables subject to ASC 310-30
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance			0
Improvement of ASC 310-30 loans	0	0	0	0
Allowance for loan losses, ending balance	0		0
Consumer
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	340	341	438	348
Charge-offs	(31)	(98)	(110)	(146)
Recoveries	15	45	30	70
Provision	47	48	13	64
Allowance for loan losses, ending balance	371	336	371	336
Consumer | Acquired receivables subject to ASC 310-30
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance			0
Improvement of ASC 310-30 loans	0	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	1,056	951	1,047	865
Charge-offs	(819)	(597)	(1,317)	(997)
Recoveries	392	367	576	532
Provision	351	206	674	527
Allowance for loan losses, ending balance	980	927	980	927
Other | Acquired receivables subject to ASC 310-30
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance			0
Improvement of ASC 310-30 loans	0	$ 0	0	$ 0
Allowance for loan losses, ending balance	$ 0		$ 0

Allowance for Loan and Lease 69

Allowance for Loan and Lease Losses - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and written loan commitments at fair value under the fair value option	$ 1,056,155		$ 1,056,155			$ 1,131,111
Loan held for sale	4,902		4,902			12,918
Loans guaranteed by U.S. Government Agencies	7,484,685		7,484,685			7,431,936
Allowance for loan leases	62,685	$ 61,917	62,685	$ 61,917	$ 66,767	64,642	$ 61,128	$ 57,200
Net reversal of provision	988	1,428	1,616	2,195
Unfunded loan commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Reserve for unfunded loan commitments	500		500			500
(Impairment) improvement of ASC 310-30 loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans guaranteed by U.S. Government Agencies	117,159		117,159			129,531
Allowance for loan leases	712		712			1,679
Net reversal of provision	1,100	$ 100	1,000	$ 300
Loans Guaranteed by US Government Authorities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans guaranteed by U.S. Government Agencies	$ 160,800		$ 160,800			$ 120,000

Allowance for Loan and Lease 70

Allowance for Loan and Lease Losses - Summary of Allowance for Loan Losses by Type (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015
Allowance for loan and lease losses
Individually evaluated for impairment	$ 22,593		$ 25,686
Collectively evaluated for impairment	39,380		37,277
Total allowance	62,685	$ 66,767	64,642	$ 61,917	$ 61,128	$ 57,200
Financing Receivables
Individually evaluated for impairment	239,648		216,429
Collectively evaluated for impairment	7,127,878		7,085,976
Loans Outstanding	7,484,685		7,431,936
Acquired receivables subject to ASC 310-30
Allowance for loan and lease losses
Total allowance	712		1,679
Financing Receivables
Loans Outstanding	117,159		129,531
Residential real estate
Allowance for loan and lease losses
Individually evaluated for impairment	3,288		3,000
Collectively evaluated for impairment	2,781		3,199
Total allowance	6,069	6,786	7,106	8,796	7,798	8,025
Financing Receivables
Individually evaluated for impairment	9,383		10,364
Collectively evaluated for impairment	886,114		918,710
Loans Outstanding	954,605		994,811
Residential real estate | Acquired receivables subject to ASC 310-30
Allowance for loan and lease losses
Total allowance	0		907
Financing Receivables
Loans Outstanding	59,108		65,737
Commercial real estate
Allowance for loan and lease losses
Individually evaluated for impairment	3,601		3,846
Collectively evaluated for impairment	12,683		13,328
Total allowance	16,996	16,623	17,946	20,904	19,405	18,014
Financing Receivables
Individually evaluated for impairment	39,574		54,005
Collectively evaluated for impairment	3,383,189		3,249,974
Loans Outstanding	3,462,510		3,348,427
Commercial real estate | Acquired receivables subject to ASC 310-30
Allowance for loan and lease losses
Total allowance	712		772
Financing Receivables
Loans Outstanding	39,747		44,448
Commercial non real estate
Allowance for loan and lease losses
Individually evaluated for impairment	4,985		6,475
Collectively evaluated for impairment	6,964		6,515
Total allowance	11,949	13,443	12,990	12,631	17,160	15,996
Financing Receivables
Individually evaluated for impairment	45,032		49,825
Collectively evaluated for impairment	1,082,786		1,079,295
Loans Outstanding	1,130,571		1,132,316
Commercial non real estate | Acquired receivables subject to ASC 310-30
Allowance for loan and lease losses
Total allowance	0		0
Financing Receivables
Loans Outstanding	2,753		3,196
Agriculture
Allowance for loan and lease losses
Individually evaluated for impairment	10,616		12,278
Collectively evaluated for impairment	15,704		12,837
Total allowance	26,320	28,519	25,115	18,323	15,473	13,952
Financing Receivables
Individually evaluated for impairment	145,233		101,840
Collectively evaluated for impairment	1,662,802		1,721,219
Loans Outstanding	1,822,834		1,838,313
Agriculture | Acquired receivables subject to ASC 310-30
Allowance for loan and lease losses
Total allowance	0		0
Financing Receivables
Loans Outstanding	14,799		15,254
Consumer
Allowance for loan and lease losses
Individually evaluated for impairment	103		87
Collectively evaluated for impairment	268		351
Total allowance	371	340	438	336	341	348
Financing Receivables
Individually evaluated for impairment	426		395
Collectively evaluated for impairment	73,011		74,301
Loans Outstanding	74,189		75,592
Consumer | Acquired receivables subject to ASC 310-30
Allowance for loan and lease losses
Total allowance	0		0
Financing Receivables
Loans Outstanding	752		896
Other
Allowance for loan and lease losses
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	980		1,047
Total allowance	980	$ 1,056	1,047	$ 927	$ 951	$ 865
Financing Receivables
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	39,976		42,477
Loans Outstanding	39,976		42,477
Other | Acquired receivables subject to ASC 310-30
Allowance for loan and lease losses
Total allowance	0		0
Financing Receivables
Loans Outstanding	$ 0		$ 0

Accounting for Certain Loans 71

Accounting for Certain Loans Acquired with Deteriorated Credit Quality - Schedule of Troubled Debt Restructurings (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	$ 39,758	$ 41,882	$ 38,124	$ 44,489
Accretion	(3,040)	(2,261)	(5,978)	(4,590)
Reclassification from (to) nonaccretable difference	1,987	222	6,559	(56)
Balance at end of period	$ 38,705	$ 39,843	$ 38,705	$ 39,843

Accounting for Certain Loans 72

Accounting for Certain Loans Acquired with Deteriorated Credit Quality - Schedule of Impaired Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	$ 223,309	$ 238,106
Recorded Investment	117,159	129,531
Carrying Value	116,447	127,852
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	69,261	76,696
Recorded Investment	59,108	65,737
Carrying Value	59,108	64,830
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	123,321	129,615
Recorded Investment	39,747	44,448
Carrying Value	39,035	43,676
Commercial non real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	11,361	11,588
Recorded Investment	2,753	3,196
Carrying Value	2,753	3,196
Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	18,474	19,174
Recorded Investment	14,799	15,254
Carrying Value	14,799	15,254
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Balance	892	1,033
Recorded Investment	752	896
Carrying Value	$ 752	$ 896

FDIC Indemnification Asset - Su

FDIC Indemnification Asset - Summary of FDIC Indemnification Asset Activity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
FDIC Indemnification Asset [Roll Forward]
Balance at beginning of period	$ 9,887	$ 13,185	$ 10,777	$ 14,722
Amortization	(1,114)	(895)	(1,981)	(1,927)
Changes in expected reimbursements from FDIC for changes in expected credit losses	(133)	1	(105)	(127)
Changes in reimbursable expenses	(299)	(78)	(538)	(427)
Reimbursements of covered losses to the FDIC	30	662	218	634
Balance at end of period	$ 8,371	$ 12,875	$ 8,371	$ 12,875

Derivative Financial Instrume74

Derivative Financial Instruments - Schedule of Derivative Positions, Notional Amounts and Estimated Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Derivative [Line Items]
Positive Fair Value	$ 7,945	$ 525
Negative Fair Value	(20,466)	(81,974)
Not Designated as Hedging Instruments | Liabilities | Interest rate swaps
Derivative [Line Items]
Notional Amount	1,049,701	1,055,822
Positive Fair Value	7,945	525
Negative Fair Value	(20,466)	(81,974)
Not Designated as Hedging Instruments | Liabilities | Mortgage loan forward sale contracts
Derivative [Line Items]
Notional Amount	36,396	60,529
Positive Fair Value	0	0
Negative Fair Value	(53)	(66)
Not Designated as Hedging Instruments | Assets | Mortgage loan commitments
Derivative [Line Items]
Notional Amount	33,561	52,333
Positive Fair Value	53	66
Negative Fair Value	$ 0	$ 0

Derivative Financial Instrume75

Derivative Financial Instruments - Effect on the Consolidated Statement of Comprehensive Income (Details) - Noninterest income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Interest rate swaps
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Income	$ 1,592	$ (40,893)	$ 60,568	$ (31,454)
Mortgage loan commitments
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Income	158	76	53	52
Mortgage loan forward sale contracts
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Income	$ (158)	$ (76)	$ (53)	$ (52)

Derivative Financial Instrume76

Derivative Financial Instruments - Summary of Offsetting Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative financial assets, gross amount	$ 7,945	$ 525
Derivative financial liabilities, gross amount	(20,466)	(81,974)
Derivative financial assets (liabilities), gross amount	(12,521)	(81,449)
Derivative financial assets, amount offset	(7,945)	(525)
Derivative financial liabilities, amount offset	7,945	525
Derivative financial assets (liabilities), Net, amount offset	0	0
Derivative financial assets, net amount presented in Consolidated Balance Sheets	0	0
Derivative financial liabilities, net amount presented in Consolidated Balance Sheets	(12,521)	(81,449)
Derivative financial assets (liabilities), net amount presented in Consolidated Balance Sheets	(12,521)	(81,449)
Derivative financial assets, Held/pledged financial instruments	0	0
Derivative financial liabilities, Held/pledged financial instruments	0	81,449
Derivative liabilities (assets), Net, Held/pledged financial instruments	0	81,449
Derivative financial asset, net amount	0	0
Derivative financial liabilities, net amount	(12,521)	0
Derivative financial assets (liabilities), net, amount offset against collateral	$ (12,521)	$ 0

Derivative Financial Instrume77

Derivative Financial Instruments - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2017	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Termination value of net liability position	$ 16.9	$ 84.4
Collateral posted, amount	$ 32.1	$ 106.1

The Fair Value Option For Cer78

The Fair Value Option For Certain Loans - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Eligible item for the fair value option	$ 4.9		$ 4.9		$ 74.1
Loans greater than 90 days past due or in nonaccrual status	9.6		9.6		9.4
Unpaid principal balance greater than 90 days past due or in nonaccrual status	11		11		10.8
Long-term loans and written loan commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total unpaid principal balance of long-term loans	1,050		1,050		$ 1,060
Eligible item for the fair value option	$ 0.3	$ 0.2	$ 0.3	$ 0.4

The Fair Value Option For Cer79

The Fair Value Option For Certain Loans - Summary of the Fair Value Option (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Change in fair value of loans	$ (5,216)	$ 35,955	$ (69,218)	$ 21,054
Long-term loans and written loan commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Change in fair value of loans	(5,216)	35,955	(69,218)	21,054
Long-term loans and written loan commitments | Noninterest Income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Change in fair value of loans	$ (5,216)	$ 35,955	$ (69,218)	$ 21,054

Core Deposits and Other Intan80

Core Deposits and Other Intangibles - Intangible Assets Amortization Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 92,109	$ 92,109
Accumulated amortization	(81,766)	(80,377)
Total	10,343	11,732
Core Deposit Intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	67,018	67,018
Accumulated amortization	(60,615)	(59,842)
Total	6,403	7,176
Brand Intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	8,464	8,464
Accumulated amortization	(4,982)	(4,700)
Total	3,482	3,764
Customer Relationships Intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	16,089	16,089
Accumulated amortization	(16,089)	(15,800)
Total	0	289
Other Intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	538	538
Accumulated amortization	(80)	(35)
Total	$ 458	$ 503

Core Deposits and Other Intan81

Core Deposits and Other Intangibles - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of core deposits and other intangibles	$ 0.6	$ 0.7	$ 1.4	$ 1.4

Core Deposits and Other Intan82

Core Deposits and Other Intangibles - Schedule of Future Amortization Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Remaining in 2017	$ 952
2,018	1,614
2,019	1,489
2,020	1,363
2,021	1,267
2022 and thereafter	3,658
Total	$ 10,343	$ 11,732

Loan Servicing Rights - Schedul

Loan Servicing Rights - Schedule of Loan Servicing Rights Activity and Valuation Allowance (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2016
Loan servicing rights
Beginning of period	$ 5,286	$ 0	$ 5,794	$ 0
Additions	0	0	0	0
Amortization	(380)	0	(888)	0
End of period	4,906	0	4,906	0
Valuation Allowance for Impairment of Recognized Servicing Assets [Roll Forward]
Beginning of period	(8)	0	(13)	0
(Additions) / reductions	5	0	10	0
End of period	(3)	0	(3)	0
Loan servicing rights, net	4,903	0	4,903	0	$ 5,781
Servicing fees received	525	0	1,073	0
Balance of loans serviced at:
Beginning of period	823,375	0	868,865	0
End of period	$ 792,779	$ 0	$ 792,779	$ 0

Loan Servicing Rights - Narrati

Loan Servicing Rights - Narrative (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015
Transfers and Servicing [Abstract]
Constant prepayment rates (as a percent)	12.10%
Discount rate (as a percent)	11.90%
Loan servicing rights, valuation allowance	$ 3	$ 8	$ 13	$ 0	$ 0	$ 0

Securities Sold Under Agreeme85

Securities Sold Under Agreements to Repurchase - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2017	Sep. 30, 2016
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities sold under agreements to repurchase	$ 131.1	$ 151.8
Securities sold under agreements to repurchase, fair value of collateral	$ 128.9	$ 152.3
Securities sold under agreements to repurchase, collateral, percentage of borrowed funds (as a percent)	102.00%

Securities Sold Under Agreeme86

Securities Sold Under Agreements to Repurchase - Maturity Schedule of Agreements (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	$ 124,472	$ 141,688
Municipal securities
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	2,542	0
Mortgage-backed securities
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	121,930	141,688
Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	124,472	138,744
Overnight and Continuous | Municipal securities
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	2,542	0
Overnight and Continuous | Mortgage-backed securities
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	121,930	138,744
Up to 30 Days
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	0	0
Up to 30 Days | Municipal securities
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 | Municipal securities
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	2,944
Greater than 90 Days | Municipal securities
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	$ 2,944

FHLB Advances and Other Borro87

FHLB Advances and Other Borrowings - Schedule of Advances, Related Party Notes (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Other	$ 1,600	$ 0
Total	264,600	871,000
Fair value adjustment	24	37
Total FHLB advances and other borrowings	264,624	871,037
Notes payable to banks
Debt Instrument [Line Items]
Federal Home Loan Bank (FHLB) notes payable and fed funds advance	$ 246,000	640,000
Notes payable to banks | Minimum
Debt Instrument [Line Items]
Stated interest rate (as a percent)	0.81%
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)	1.06%
Federal Home Loan Bank (FHLB) notes payable and fed funds advance	$ 17,000	$ 231,000

FHLB Advances and Other Borro88

FHLB Advances and Other Borrowings - Narrative (Details) - USD ($)	6 Months Ended
	Mar. 31, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Current borrowing capacity	$ 1,720,000,000
Loans pledged to the Federal Home Loan Bank	3,320,000,000	$ 3,110,000,000
Wells Fargo | Revolving Credit Facility
Debt Instrument [Line Items]
Borrowing capacity	$ 10,000,000
Unused capacity fee (as a percent)	0.20%
Interest rate at end of period (as a percent)	2.98%
Outstanding advances	$ 0	$ 0
Wells Fargo | Revolving Credit Facility | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	2.00%

FHLB Advances and Other Borro89

FHLB Advances and Other Borrowings - Schedule of Due or Callable Notes (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Total	$ 108,220	$ 111,873
FHLB Advances and Related Party Notes Payable
Debt Instrument [Line Items]
Remaining in 2017	118,600
2,018	31,000
2,019	0
2,020	0
2,021	0
2022 and thereafter	115,000
Total	$ 264,600

Subordinated Debentures and S90

Subordinated Debentures and Subordinated Notes Payable - Junior Subordinated Deferrable Interest Debentures (Details) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
	Dec. 31, 2016shares	Mar. 31, 2017USD ($)trust$ / sharesshares	Sep. 30, 2016USD ($)
Debt Instrument [Line Items]
Maximum interest payment deferral period		5 years
Total subordinated debentures and subordinated notes payable		$ 108,220	$ 111,873
Junior Subordinated Debt
Debt Instrument [Line Items]
Total subordinated debentures and subordinated notes payable		73,465	77,155
Common shares held in other assets		$ 2,520	2,520
Junior Subordinated Debt | HF Capital Trust V, variable rate of 1.83%, plus 3 month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		1.83%
Common shares held in other assets		$ 310	$ 310
Number of shares redeemed (in shares) | shares	5,000
Trust Preferred Securities Subject to Mandatory Redemption
Debt Instrument [Line Items]
Number of trusts | trust		7
Number of shares caused to be issued (in shares) | shares		73,400
Par value per shares issued (in dollars per share) | $ / shares		$ 1,000
Trust Preferred Securities Subject to Mandatory Redemption | London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		1.48%
Trust Preferred Securities Subject to Mandatory Redemption | London Interbank Offered Rate (LIBOR) | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		3.35%

Subordinated Debentures and S91

Subordinated Debentures and Subordinated Notes Payable - Subordinated Notes Payable (Details) - Subordinated Debt - USD ($)	12 Months Ended
	Sep. 30, 2015	Mar. 31, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Face amount of debt issued	$ 35,000,000
Stated interest rate (as a percent)	4.875%
Redemption price, percentage of principal (as a percent)	100.00%
Unamortized debt issuance costs		$ 245,000	$ 282,000
London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	3.15%

Subordinated Debentures and S92

Subordinated Debentures and Subordinated Notes Payable - Summary of Subordinated Debentures and Notes Payable (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2015
Debt Instrument [Line Items]
Total	$ 108,220	$ 111,873
Junior Subordinated Debt
Debt Instrument [Line Items]
Total junior subordinated debentures payable, amount outstanding	75,920	80,920
Total junior subordinated debentures payable, common shares held in other assets	2,520	2,520
Less: fair value adjustment	(2,455)	(3,765)
Total	73,465	77,155
Junior Subordinated Debt | GW Statutory Trust IV, variable rate of 2.85%, plus 3 month LIBOR
Debt Instrument [Line Items]
Total junior subordinated debentures payable, amount outstanding	23,093	23,093
Total junior subordinated debentures payable, common shares held in other assets	$ 693	693
Basis spread on variable rate (as a percent)	2.85%
Junior Subordinated Debt | GW Statutory Trust VI, variable rate of 1.48%, plus 3 month LIBOR
Debt Instrument [Line Items]
Total junior subordinated debentures payable, amount outstanding	$ 30,928	30,928
Total junior subordinated debentures payable, common shares held in other assets	$ 928	928
Basis spread on variable rate (as a percent)	1.48%
Junior Subordinated Debt | SSB Trust II, variable rate of 1.85%, plus 3 month LIBOR
Debt Instrument [Line Items]
Total junior subordinated debentures payable, amount outstanding	$ 2,062	2,062
Total junior subordinated debentures payable, common shares held in other assets	$ 62	62
Basis spread on variable rate (as a percent)	1.85%
Junior Subordinated Debt | HF Capital Trust III, variable rate of 3.35%, plus 3 month LIBOR
Debt Instrument [Line Items]
Total junior subordinated debentures payable, amount outstanding	$ 5,155	5,155
Total junior subordinated debentures payable, common shares held in other assets	$ 155	155
Basis spread on variable rate (as a percent)	3.35%
Junior Subordinated Debt | HF Capital Trust IV, variable rate of 3.10%, plus 3 month LIBOR
Debt Instrument [Line Items]
Total junior subordinated debentures payable, amount outstanding	$ 7,217	7,217
Total junior subordinated debentures payable, common shares held in other assets	$ 217	217
Basis spread on variable rate (as a percent)	3.10%
Junior Subordinated Debt | HF Capital Trust V, variable rate of 1.83%, plus 3 month LIBOR
Debt Instrument [Line Items]
Total junior subordinated debentures payable, amount outstanding	$ 5,310	10,310
Total junior subordinated debentures payable, common shares held in other assets	$ 310	310
Basis spread on variable rate (as a percent)	1.83%
Junior Subordinated Debt | HF Capital Trust VI, variable rate of 1.65%, plus 3 month LIBOR
Debt Instrument [Line Items]
Total junior subordinated debentures payable, amount outstanding	$ 2,155	2,155
Total junior subordinated debentures payable, common shares held in other assets	$ 155	155
Basis spread on variable rate (as a percent)	1.65%
Subordinated Debt
Debt Instrument [Line Items]
Less: unamortized debt issuance costs	$ (245)	(282)
Total	34,755	34,718
Stated interest rate (as a percent)			4.875%
Subordinated Debt | Fixed to floating rate, 4.875% per annum
Debt Instrument [Line Items]
Total junior subordinated debentures payable, amount outstanding	$ 35,000	$ 35,000
Stated interest rate (as a percent)	4.875%

Employee Benefit Plans - Profit

Employee Benefit Plans - Profit Sharing Plan (Details) - Multiple employer 401(k) profit sharing plan $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)	Mar. 31, 2017USD ($)year	Mar. 31, 2016USD ($)
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 | $	$ 1.3	$ 0.6	$ 2.9	$ 2

Employee Benefit Plans - Summar

Employee Benefit Plans - Summary of the Components of Net Periodic Benefit Cost (Details) - Pension Plan - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Net periodic benefit cost
Service cost	$ 12	$ 0	$ 24	$ 0
Interest cost	56	0	112	0
Expected return on plan assets	(64)	0	(128)	0
Amortization of prior losses	62	0	124	0
Net periodic benefit cost	$ 66	$ 0	$ 132	$ 0

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment award, award vesting period			3 years
Share-based compensation expense	$ 2	$ 0.7	$ 3.6	$ 1.8
Tax benefit from compensation expense	0.7	$ 0.3	$ 1.4	$ 0.7
Target performance level (as a percent)			100.00%
Share-based compensation, compensation cost not yet recognized	$ 7.5		$ 7.5
Share-based compensation, compensation cost not yet recognized, recognition period			2 years 8 months 2 days
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-established target levels (as a percent)			0.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target performance level (as a percent)			150.00%
Pre-established target levels (as a percent)			150.00%
Performance shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Approximate number of shares to be issued (in shares)			409,847
Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of vested stock awards			$ 1.4

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Restricted Share and Performance-Based Stock Award Activity (Details) - $ / shares	6 Months Ended	12 Months Ended
	Mar. 31, 2017	Sep. 30, 2016
Restricted shares
Common Shares
Shares, beginning of fiscal year (in shares)	160,335	80,446
Granted (in shares)	89,135	113,543
Vested and issued (in shares)	(67,213)	(25,729)
Forfeited (in shares)	(1,868)	(7,925)
Canceled (in shares)	0	0
Shares, end of period (in shares)	180,389	160,335
Vested, but not issuable at end of period (in shares)	32,759	24,480
Weighted-Average Grant Date Fair Value
Shares, beginning of fiscal year (in dollars per share)	$ 26.89	$ 18.18
Granted (in dollars per share)	39.36	30.95
Vested and issued (in dollars per share)	27	18.11
Forfeited (in dollars per share)	30	25.09
Canceled (in dollars per share)	0	0
Shares, end of period (in dollars per share)	32.98	26.89
Vested, but not issuable at end of period (in dollars per share)	$ 30.53	$ 26.14
Performance shares
Common Shares
Shares, beginning of fiscal year (in shares)	236,185	211,026
Granted (in shares)	40,204	43,371
Vested and issued (in shares)	0	(55)
Forfeited (in shares)	(3,158)	(18,157)
Canceled (in shares)	0	0
Shares, end of period (in shares)	273,231	236,185
Weighted-Average Grant Date Fair Value
Shares, beginning of fiscal year (in dollars per share)	$ 20.28	$ 18
Granted (in dollars per share)	39.43	30.78
Vested and issued (in dollars per share)	0	18
Forfeited (in dollars per share)	20.93	18.83
Canceled (in dollars per share)	0	0
Shares, end of period (in dollars per share)	$ 23.09	$ 20.28

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value Measurements of Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	$ 1,350,893	$ 1,317,386
Derivatives-liabilities	12,574	81,515
Fair value loans and written loan commitments	1,056,155	1,131,111
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	228,710	230,980
Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	1,051,093	1,024,838
States and political subdivision securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	70,061	55,484
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	0	5,022
Fair value, measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	1,350,893	1,317,386
Derivatives-assets	53	66
Derivatives-liabilities	12,574	81,515
Fair value loans and written loan commitments	1,056,155	1,131,111
Fair value, measurements, recurring | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	228,710	230,980
Fair value, measurements, recurring | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	1,051,093	1,024,838
Fair value, measurements, recurring | States and political subdivision securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	70,061	55,484
Fair value, measurements, recurring | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	0	5,022
Fair value, measurements, recurring | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	1,029	1,062
Fair value, measurements, recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	228,710	230,980
Derivatives-assets		0
Derivatives-liabilities	0	0
Fair value loans and written loan commitments	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]
Total securities available for sale	228,710	230,980
Fair value, measurements, recurring | Level 1 | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total 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]
Total securities available for sale	0	0
Fair value, measurements, recurring | Level 1 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total 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]
Total 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]
Total securities available for sale	1,120,959	1,085,091
Derivatives-assets	53	66
Derivatives-liabilities	12,574	81,515
Fair value loans and written loan commitments	1,056,155	1,131,111
Fair value, measurements, recurring | Level 2 | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total 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]
Total securities available for sale	1,051,093	1,024,838
Fair value, measurements, recurring | Level 2 | States and political subdivision securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	68,837	54,169
Fair value, measurements, recurring | Level 2 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	0	5,022
Fair value, measurements, recurring | Level 2 | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	1,029	1,062
Fair value, measurements, recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	1,224	1,315
Derivatives-assets	0	0
Derivatives-liabilities	0	0
Fair value loans and written loan commitments	0	0
Fair value, measurements, recurring | Level 3 | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total 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]
Total 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]
Total securities available for sale	1,224	1,315
Fair value, measurements, recurring | Level 3 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	0	0
Fair value, measurements, recurring | Level 3 | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	$ 0	$ 0

Fair Value Measurements - Sch98

Fair Value Measurements - Schedule of Changes in Level 3 Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 1,224	$ 1,458	$ 1,315	$ 1,835
Principal paydown	0	0	(91)	(77)
Realized loss on securities	0	0	0	(300)
Balance, end of period	$ 1,224	$ 1,458	$ 1,224	$ 1,458

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Mortgage Loans Held-For-Sale, Fair Value Measurement (Details) - Fair value, measurements, nonrecurring - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Other real estate owned	$ 3,071	$ 6,911
Impaired loans	217,055	190,743
Loans held for sale, at lower of cost or fair value	4,902	12,918
Loan servicing rights	4,903	5,781
Property held for sale	5,258	8,112
Level 1
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Other real estate owned	0	0
Impaired loans	0	0
Loans held for sale, at lower of cost or fair value	0	0
Loan servicing rights	0	0
Property held for sale	0	0
Level 2
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Other real estate owned	0	0
Impaired loans	0	0
Loans held for sale, at lower of cost or fair value	4,902	12,918
Loan servicing rights	0	0
Property held for sale	0	0
Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Other real estate owned	3,071	6,911
Impaired loans	217,055	190,743
Loans held for sale, at lower of cost or fair value	0	0
Loan servicing rights	4,903	5,781
Property held for sale	$ 5,258	$ 8,112

Fair Value Measurements - Su100

Fair Value Measurements - Summary of Valuation Techniques and Significant Unobservable Inputs Used to Measure Level 3 Fair Value Measurements (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2017	Sep. 30, 2016
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Property held for sale	$ 5,258	$ 8,112
Fair value, measurements, nonrecurring
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Other real estate owned	3,071	6,911
Impaired loans	217,055	190,743
Loan servicing rights	4,903	5,781
Fair value, measurements, nonrecurring | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Other real estate owned	3,071	6,911
Impaired loans	217,055	190,743
Loan servicing rights	4,903	$ 5,781
Property held for sale	$ 5,258
Fair value, measurements, nonrecurring | Level 3 | Loan servicing rights | Discounted cash flows | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Constant prepayment rate (as a percent)	9.00%
Discount rate (as a percent)	9.50%
Fair value, measurements, nonrecurring | Level 3 | Loan servicing rights | Discounted cash flows | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Constant prepayment rate (as a percent)	21.00%
Discount rate (as a percent)	16.00%
Fair value, measurements, nonrecurring | Level 3 | Loan servicing rights | Discounted cash flows | Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Constant prepayment rate (as a percent)	12.10%
Discount rate (as a percent)	11.90%

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details)	6 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Derivative, remaining maturity (or less)	180 days

Fair Value Measurements - Sc102

Fair Value Measurements - Schedule of Fair Values for Balance Sheet Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Level 1 | Carrying Amount
Assets
Cash and cash equivalents	$ 335,929	$ 524,611
Level 1 | Fair Value
Assets
Cash and cash equivalents	335,929	524,611
Level 3 | Carrying Amount
Assets
Loans, net excluding fair valued loans and loans held for sale	7,573,684	7,473,973
Level 3 | Fair Value
Assets
Loans, net excluding fair valued loans and loans held for sale	7,506,331	7,433,851
Level 2 | Carrying Amount
Assets
Accrued interest receivable	43,690	49,531
Cash surrender value of life insurance policies	29,188	29,166
Federal Home Loan Bank stock	22,514	47,025
Liabilities
Deposits	9,091,918	8,604,790
FHLB advances and other borrowings	264,624	871,037
Securities sold under repurchase agreements	124,472	141,688
Accrued interest payable	3,983	4,074
Subordinated debentures and subordinated notes payable	108,220	111,873
Level 2 | Fair Value
Assets
Accrued interest receivable	43,690	49,531
Cash surrender value of life insurance policies	29,188	29,166
Federal Home Loan Bank stock	22,514	47,025
Liabilities
Deposits	9,092,262	8,603,708
FHLB advances and other borrowings	265,315	874,763
Securities sold under repurchase agreements	124,472	141,688
Accrued interest payable	3,983	4,074
Subordinated debentures and subordinated notes payable	$ 108,151	$ 112,826

Earnings per Share - Schedule o

Earnings per Share - Schedule of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Net income	$ 35,162	$ 30,674	$ 72,065	$ 61,135
Weighted average common shares outstanding (in shares)	58,788,802	55,269,557	58,769,662	55,261,634
Dilutive effect of stock based compensation (in shares)	284,867	139,319	263,125	139,530
Weighted average common shares outstanding for diluted earnings per share calculation (in shares)	59,073,669	55,408,876	59,032,787	55,401,164
Basic earnings per share (in dollars per share)	$ 0.60	$ 0.56	$ 1.23	$ 1.11
Diluted earnings per share (in dollars per share)	$ 0.60	$ 0.55	$ 1.22	$ 1.10

Earnings per Share - Narrative

Earnings per Share - Narrative (Details) - shares	6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Performance shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of earnings per share (in shares)	50,076	36,696
Stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of earnings per share (in shares)	53,126	174,415