Washington Federal (WAFD) 10-Q 4 May 21 2021 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-34654
Entity Registrant Name	WASHINGTON FEDERAL INC
Entity Incorporation, State or Country Code	WA
Entity Tax Identification Number	91-1661606
Entity Address, Address Line One	425 Pike Street
Entity Address, City or Town	Seattle
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98101
City Area Code	206
Local Phone Number	624-7930
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		72,404,471
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Entity Central Index Key	0000936528
Current Fiscal Year End Date	--09-30
Common Stock, $1.00 par value per share
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $1.00 par value per share
Trading Symbol	WAFD
Security Exchange Name	NASDAQ
Depositary Shares, Each Representing a 1/40th Interest in a Share of 4.875% Fixed Rate Series A Non-Cumulative Perpetual Preferred Stock
Document Information [Line Items]
Title of 12(b) Security	Depositary Shares, Each Representing a 1/40th Interest in a Share of 4.875% Fixed Rate Series A Non-Cumulative Perpetual Preferred Stock
Trading Symbol	WAFDP
Security Exchange Name	NASDAQ

CONSOLIDATED STATEMENTS OF FINA

CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
ASSETS
Cash and cash equivalents	$ 2,318,447	$ 1,702,977
Available-for-sale securities, at fair value	2,438,902	2,249,492
Held-to-maturity securities, at amortized cost	494,089	705,838
Loans receivable, net of allowance for loan losses	13,035,423	12,792,317
Interest receivable	54,073	53,799
Premises and equipment, net	259,560	252,805
Real estate owned	5,316	4,966
FHLB and FRB stock	119,991	141,990
Bank owned life insurance	230,520	227,749
Intangible assets, including goodwill of $302,707 and $302,707	309,086	309,906
Federal and state income tax assets, net	0	5,708
Other assets	268,174	346,508
Assets	19,533,581	18,794,055
Customer accounts
Transaction deposit accounts	11,228,666	9,806,432
Time deposit accounts	3,590,755	3,973,192
Total customer accounts	14,819,421	13,779,624
FHLB advances	2,150,000	2,700,000
Advance payments by borrowers for taxes and insurance	36,289	49,462
Federal and state income tax liabilities, net	13,424	0
Accrued expenses and other liabilities	181,494	250,836
Liabilities	17,200,628	16,779,922
Commitments and Contingencies
Shareholders’ equity
Preferred stock, $1.00 par value, 5,000,000 shares authorized; 300,000 and 0 shares issued; 300,000 and 0 shares outstanding	300,000	0
Common stock, $1.00 par value, 300,000,000 shares authorized; 135,980,008 and 135,727,237 shares issued; 73,084,591 and 75,689,364 shares outstanding	135,980	135,727
Additional paid-in capital	1,675,772	1,678,843
Accumulated other comprehensive income (loss), net of taxes	81,176	16,953
Treasury stock, at cost; 62,895,417 and 60,037,873 shares	(1,328,068)	(1,238,296)
Retained earnings	1,468,093	1,420,906
Total stockholders' equity	2,332,953	2,014,133
Liabilities and equity	$ 19,533,581	$ 18,794,055

CONSOLIDATED STATEMENTS OF FI_2

CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Statement of Financial Position [Abstract]
Allowance for credit losses on loans	$ 172,653	$ 166,955
Goodwill	$ 302,707	$ 302,707
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	300,000	0
Preferred stock, shares outstanding (in shares)	300,000	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	135,980,008	135,727,237
Common stock, shares outstanding (in shares)	73,084,591	75,689,364
Treasury stock, shares (in shares)	62,895,417	60,037,873

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
INTEREST INCOME
Loans receivable	$ 132,757	$ 138,549	$ 266,428	$ 280,695
Mortgage-backed securities	6,696	14,341	13,926	29,953
Investment securities and cash equivalents	7,301	6,728	14,222	13,794
Interest income	146,754	159,618	294,576	324,442
INTEREST EXPENSE
Customer accounts	10,729	28,638	24,839	60,119
FHLB advances	11,991	13,368	25,189	27,026
Interest expense	22,720	42,006	50,028	87,145
Net interest income	124,034	117,612	244,548	237,297
Provision (release) for credit losses	0	8,200	3,000	4,450
Net interest income after provision (release)	124,034	109,412	241,548	232,847
OTHER INCOME
Gain (loss) on sale of investment securities	0	15,028	0	15,028
Gain (loss) on termination of hedging derivatives	14,110	0	14,110	0
Prepayment penalty on long-term debt	(13,788)	(13,809)	(13,788)	(13,809)
Loan fee income	$ 872	$ 3,048	$ 3,264	$ 4,852
Revenue, Product and Service [Extensible List]	us-gaap:DepositAccountMember	us-gaap:DepositAccountMember	us-gaap:DepositAccountMember	us-gaap:DepositAccountMember
Deposit fee income	$ 5,960	$ 6,099	$ 11,986	$ 12,359
Other income	7,323	5,875	12,775	44,187
Other income, total	14,477	16,241	28,347	62,617
OTHER EXPENSE
Compensation and benefits	43,632	38,617	86,355	75,248
Occupancy	10,473	10,913	20,065	21,048
FDIC insurance premiums	3,755	2,470	7,018	4,940
Product delivery	4,401	3,897	9,338	8,164
Information technology	10,696	11,501	22,527	28,608
Other expense	8,789	12,035	17,853	24,061
Other expense, total	81,746	79,433	163,156	162,069
Gain (loss) on real estate owned, net	34	31	(415)	(855)
Income before income taxes	56,799	46,251	106,324	132,540
Income tax expense	11,928	9,874	22,502	28,297
Net income	44,871	36,377	83,822	104,243
Dividends on preferred stock	2,722	0	2,722	0
Net income available to common shareholders	$ 42,149	$ 36,377	$ 81,100	$ 104,243
PER SHARE DATA
Basic earnings per common share (in dollars per share)	$ 0.56	$ 0.47	$ 1.07	$ 1.34
Diluted earnings per common share (in dollars per share)	0.56	0.47	1.07	1.34
Dividends paid on common stock per share (in dollars per share)	$ 0.23	$ 0.22	$ 0.45	$ 0.43
Basic weighted average number of shares outstanding (in shares)	75,354,765	76,987,532	75,576,288	77,737,977
Diluted weighted average number of shares outstanding (in shares)	75,393,464	77,007,118	75,582,426	77,776,304

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 44,871	$ 36,377	$ 83,822	$ 104,243
Other comprehensive income (loss) net of tax:
Net unrealized gain (loss) during the period on available-for-sale investment securities, net of tax	(3,729)	11,617	5,262	9,893
Reclassification adjustment of net (gain) loss from sale of available-for-sale securities included in net income, net of tax	0	(11,572)	0	(11,572)
Other comprehensive income (loss) on available-for-sale securities, net of tax	(3,729)	45	5,262	(1,679)
Net unrealized gain (loss) during the period on borrowings cash flow hedges, net of tax	54,335	(9,570)	69,826	(7,152)
Reclassification adjustment of net (gain) loss included in net income during the period from hedging derivatives, net of tax	(10,865)	0	(10,865)	0
Other comprehensive income (loss) on borrowing cash flow hedges, net of tax	43,470	(9,570)	58,961	(7,152)
Other comprehensive income (loss)	39,741	(9,525)	64,223	(8,831)
Comprehensive income	$ 84,612	$ 26,852	$ 148,045	$ 95,412

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Related tax benefit (expense) for net unrealized gain (loss) on available-for-sale debt securities	$ 1,114	$ (3,468)	$ (1,572)	$ (3,043)
Reclassification adjustment of net (gain) loss from sale of available-for-sale securities included in net income, tax	0	3,456	0	3,456
Related tax benefit (expense) for net unrealized gain (loss) on borrowing cash flow hedges	(16,230)	2,858	(20,857)	2,161
Reclassification adjustment of net (gain) loss included in net income during the period from hedging derivatives, tax	$ 3,245	$ 0	$ 3,245	$ 0

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Preferred Stock	Common Stock	Paid-in Capital	Retained Earnings	Retained EarningsCumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Balance, beginning of period at Sep. 30, 2019	$ 2,032,995	$ (21,945)		$ 135,540	$ 1,672,417	$ 1,335,909	$ (21,945)	$ 15,292	$ (1,126,163)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	104,243					104,243
Other comprehensive income (loss)	(8,831)							(8,831)
Dividends on common stock	(33,374)					(33,374)
Proceeds from stock-based awards	115			6	109
Stock-based compensation expense	3,498			196	3,302
Treasury stock acquired	(112,089)								(112,089)
Balance, end of period at Mar. 31, 2020	$ 1,964,612			135,742	1,675,828	1,384,833		6,461	(1,238,252)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends per share (in dollars per share)	$ 0.43
Balance, beginning of period at Dec. 31, 2019	$ 2,031,127			135,720	1,673,666	1,365,397		15,986	(1,159,642)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	36,377					36,377
Other comprehensive income (loss)	(9,525)							(9,525)
Dividends on common stock	(16,941)					(16,941)
Proceeds from stock-based awards	65			3	62
Stock-based compensation expense	2,119			19	2,100
Treasury stock acquired	(78,610)								(78,610)
Balance, end of period at Mar. 31, 2020	$ 1,964,612			135,742	1,675,828	1,384,833		6,461	(1,238,252)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends per share (in dollars per share)	$ 0.22
Balance, beginning of period at Sep. 30, 2020	$ 2,014,133		$ 0	135,727	1,678,843	1,420,906		16,953	(1,238,296)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	83,822					83,822
Other comprehensive income (loss)	64,223							64,223
Issuance of preferred stock, net	293,325		300,000		(6,675)
Dividends on common stock	(33,913)					(33,913)
Dividends on preferred stock	(2,722)					(2,722)
Proceeds from stock-based awards	330			20	310
Stock-based compensation expense	3,527			233	3,294
Treasury stock acquired	(89,772)								(89,772)
Balance, end of period at Mar. 31, 2021	$ 2,332,953		300,000	135,980	1,675,772	1,468,093		81,176	(1,328,068)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends per share (in dollars per share)	$ 0.45
Balance, beginning of period at Dec. 31, 2020	$ 2,061,767		0	135,938	1,680,111	1,443,280		41,435	(1,238,997)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	44,871					44,871
Other comprehensive income (loss)	39,741							39,741
Issuance of preferred stock, net	293,325		300,000		(6,675)
Dividends on common stock	(17,336)					(17,336)
Dividends on preferred stock	(2,722)
Proceeds from stock-based awards	300			18	282
Stock-based compensation expense	2,078			24	2,054
Treasury stock acquired	(89,071)								(89,071)
Balance, end of period at Mar. 31, 2021	$ 2,332,953		$ 300,000	$ 135,980	$ 1,675,772	$ 1,468,093		$ 81,176	$ (1,328,068)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends per share (in dollars per share)	$ 0.23

CONSOLIDATED STATEMENTS OF SH_2

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended	6 Months Ended
	Mar. 31, 2021	Mar. 31, 2021
Statement of Stockholders' Equity [Abstract]
Dividends paid on common stock per share (in dollars per share)	$ 0.23	$ 0.45
Dividends paid on preferred stock, per share (in dollars per share)	$ 9.0729	$ 9.0729

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 83,822	$ 104,243
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization, accretion and other, net	36,608	464
Stock-based compensation expense	3,527	3,498
Provision (release) for credit losses	3,000	4,450
Loss (gain) on sale of investment securities	0	(15,028)
Net realized (gain) loss on sales of premises, equipment, and real estate owned	37	(33,115)
Impairment loss on premises and equipment	0	5,931
Prepayment penalty from repayment of borrowings	13,788	13,809
Gain on early termination of long term borrowing hedge	(14,110)	0
Decrease (increase) in accrued interest receivable	(274)	2,781
Decrease (increase) in federal and state income tax receivable	5,708	0
Decrease (increase) in cash surrender value of bank owned life insurance	(2,771)	(2,850)
Decrease (increase) in other assets	156,599	(99,335)
Increase (decrease) in federal and state income tax liabilities	(5,760)	60
Increase (decrease) in accrued expenses and other liabilities	(75,419)	66,049
Net cash provided by (used in) operating activities	204,755	50,957
CASH FLOWS FROM INVESTING ACTIVITIES
Origination of loans and principal repayments, net	(192,028)	(31,259)
Loans purchased	(73,208)	0
FHLB & FRB stock purchased	(188,001)	(201,200)
FHLB & FRB stock redeemed	210,000	169,200
Available-for-sale securities purchased	(522,454)	(159,884)
Principal payments and maturities of available-for-sale securities	338,869	132,690
Proceeds from sales of available-for-sale securities	0	204,351
Principal payments and maturities of held-to-maturity securities	206,868	147,142
Proceeds from sales of real estate owned	637	2,116
Net cash received (paid) in business combinations	0	(2,777)
Proceeds from sales of premises and equipment	3,376	53,790
Premises and equipment purchased and REO improvements	(20,260)	(10,868)
Net cash provided by (used in) investing activities	(236,201)	303,301
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase (decrease) in customer accounts	1,039,797	97,657
Proceeds from borrowings	4,700,007	5,030,000
Repayments of borrowings	(5,263,795)	(4,243,809)
Proceeds from the early termination of long term borrowing hedge	14,110	0
Proceeds from stock-based awards	330	115
Proceeds from issuance of preferred stock, net	293,325	0
Dividends paid on common stock	(33,913)	(33,374)
Treasury stock purchased	(89,772)	(112,089)
Increase (decrease) in advances payments by borrowers for taxes and insurance	(13,173)	(16,342)
Net cash provided by (used in) financing activities	646,916	722,158
Increase (decrease) in cash and cash equivalents	615,470	1,076,416
Cash, cash equivalents and restricted cash at beginning of period	1,702,977	419,158
Cash, cash equivalents and restricted cash at end of period	2,318,447	1,495,574
Non-cash investing activities
Real estate acquired through foreclosure	105	317
Non-cash financing activities
Preferred stock dividend payable	2,722	0
Cash paid (received) during the period for
Interest	41,707	87,948
Income taxes	$ 14,745	$ 21,000

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Company and Nature of Operations - Washington Federal Bank, National Association, a federally-insured national bank dba WaFd Bank (the “Bank” or “WaFd Bank”), was founded on April 24, 1917 in Ballard, Washington and is engaged primarily in providing lending, depository, insurance and other banking services to consumers, mid-sized to large businesses, and owners and developers of commercial real estate. Washington Federal, Inc., a Washington corporation (the “Company”), was formed as the Bank’s holding company in November, 1994. As used throughout this document, the terms “Washington Federal” or the “Company” refer to the Company and its consolidated subsidiaries, and the term “Bank” refers to the operating subsidiary, Washington Federal Bank, National Association. The Company is headquartered in Seattle, Washington. The Bank conducts its activities through a network of 232 bank branches located in Washington, Oregon, Idaho, Utah, Arizona, Nevada, New Mexico and Texas. Risks and Uncertainties - The worldwide spread of coronavirus (“COVID-19”) has created significant uncertainty in the global economy. There have been no comparable recent events that provide guidance as to the effect the spread of COVID-19 as a global pandemic may have, and, as a result, the ultimate impact of COVID-19 and the extent to which COVID-19 and the related government actions impact the Company’s business, results of operations and financial condition will depend on future developments, which are highly uncertain and difficult to predict. Basis of Presentation - The Company has prepared the consolidated unaudited interim financial statements included in this report. All intercompany transactions and accounts have been eliminated in consolidation. The preparation of financial statements, in conformity with accounting principles generally accepted in the United States of America (“GAAP”), requires management to make estimates and assumptions that affect amounts reported in the financial statements. Actual results could differ from these estimates. In the opinion of management, all adjustments (consisting only of normal recurring adjustments) necessary for a fair presentation are reflected in the interim financial statements. The information included in this Form 10-Q should be read in conjunction with the financial statements and related notes in the Company's 2020 Annual Report on Form 10-K filed with the Securities and Exchange Commission ("SEC") on November 23, 2020 ("2020 Annual Financial Statements"). Interim results are not necessarily indicative of results for a full year. The Company early adopted FASB Accounting Standards Update (“ASU”) 2016-13, Financial Instruments - Credit Losses ("ASC 326") during fiscal 2020 and based on the application of the modified retrospective method it became effective on October 1, 2019 for all financial assets measured at amortized cost (primarily loans receivable and held-to-maturity debt securities) and off-balance-sheet credit exposures. The Company recorded a decrease to retained earnings of $21,945,000 as of October 1, 2019 for the cumulative effect of adopting ASC 326. Summary of Significant Accounting Policies - The significant accounting policies used in preparation of the Company's consolidated financial statements are disclosed in its 2020 Annual Financial Statements. There have not been any significant changes in the Company's significant accounting policies compared to those contained in its 2020 Annual Financial Statements for the year ended September 30, 2020. Preferred Stock - On February 8, 2021, in connection with an underwritten public offering, the Company issued 300,000 shares of 4.875% Noncumulative Perpetual Series A Preferred Stock (“Series A Preferred Stock”). Net proceeds, after underwriting discounts and expenses, were $293,325,000. The public offering consisted of the issuance and sale of 12,000,000 depositary shares, each representing a 1/40th interest in a share of the Series A Preferred Stock, at a public offering price of $25.00 per depositary share. Holders of the depositary shares are entitled to all proportional rights and preferences of the Series A Preferred Stock (including, dividend, voting, redemption and liquidation rights). The depositary shares are traded on the NASDAQ Global Select Market under the symbol "WAFDP." The Series A Preferred Stock is redeemable at the option of the Company, subject to all applicable regulatory approvals, on or after April 15, 2026. Restricted Cash Balances - Based on the level of vault cash on hand, the Company was not required to maintain cash reserve balances with the Federal Reserve Bank as of March 31, 2021. As of March 31, 2021 and September 30, 2020, the Company pledged cash collateral related to derivative contracts of $1,500,000 and $97,600,000, respectively. Equity Securities - The Company records equity securities within Other assets in its Consolidated Statements of Financial Condition. Investments in equity securities with readily determinable fair values (marketable) are measured at fair value, with changes in the fair value recognized as a component of Other income in the Consolidated Statements of Operations. Investments in equity investments that do not have readily determinable fair values (non-marketable) are accounted for at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or similar investment of the same issuer, also referred to as the measurement alternative. Any adjustments to the carrying value of these investments are recorded in Other income in the Consolidated Statements of Operations. Allowance for Credit Losses (Loans Receivable) - Effective October 1, 2019, the Company has applied ASC 326 for the periods presented herein , so the allowance calculation is based on current expected credit loss methodology ("CECL"). Prior to October 1, 2019, the calculation was based on incurred loss methodology. The Company maintains an allowance for credit losses (“ACL”) for the expected credit losses of the loan portfolio as well as unfunded loan commitments. The amount of ACL is based on ongoing, quarterly assessments by management. The CECL methodology requires an estimate of the credit losses expected over the life of an exposure (or pool of exposures) and replaces the incurred loss methodology’s threshold that delayed the recognition of a credit loss until it was probable a loss event was incurred. The ACL consists of the allowance for loan losses and the reserve for unfunded commitments. The estimate of expected credit losses under the CECL methodology is based on relevant information about past events, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amounts. Historical loss experience is generally the starting point for estimating expected credit losses. We then consider whether the historical loss experience should be adjusted for asset-specific risk characteristics or current conditions at the reporting date that did not exist over the period that historical experience was based for each loan type. Finally, we consider forecasts about future economic conditions or changes in collateral values that are reasonable and supportable. Portfolio segment is defined as the level at which an entity develops and documents a systematic methodology to determine its ACL. The Company has designated two loan portfolio segments, commercial loans and consumer loans. These loan portfolio segments are further disaggregated into classes, which represent loans of similar type, risk characteristics, and methods for monitoring and assessing credit risk. The commercial loan portfolio segment is disaggregated into five classes: multi-family, commercial real estate, commercial and industrial, construction, and land acquisition and development. The risk of loss for the commercial loan portfolio segment is generally most indicated by the credit risk rating assigned to each borrower. Commercial loan risk ratings are determined by experienced senior credit officers based on specific facts and circumstances and are subject to periodic review by an independent internal team of credit specialists. The consumer loan portfolio segment is disaggregated into five classes: single-family-residential mortgage, custom construction, consumer lot loans, home equity lines of credit, and other consumer. The risk of loss for the consumer loan portfolio segment is generally most indicated by delinquency status and general economic factors. Each commercial and consumer loan portfolio class may also be further segmented based on risk characteristics. For most of our loan portfolio classes, the historical loss experience is determined using a cohort methodology. This method pools loans into groups (“cohorts”) sharing similar risk characteristics and tracks each cohort’s net charge-offs over the lives of the loans to calculate a historical loss rate. The historical loss rates for each cohort are then averaged to calculate an overall historical loss rate which is applied to the current loan balance to arrive at the quantitative baseline portion of the allowance for credit losses for the respective loan portfolio class. For certain loan portfolio classes, the Company determined there was not sufficient historical loss information to calculate a meaningful historical loss rate using the cohort methodology. For any such loan portfolio class, the weighted-average remaining maturity (“WARM”) methodology is being utilized until sufficient historical loss data is obtained. The WARM method multiplies an average annual loss rate by the expected remaining life of the loan pool to arrive at the quantitative baseline portion of the allowance for credit losses for the respective loan portfolio class. The Company also considers qualitative adjustments to the historical loss rate for each loan portfolio class. The qualitative adjustments for each loan class consider the conditions over the period from which historical loss experience was based and are split into two components: 1) asset or class specific risk characteristics or current conditions at the reporting date related to portfolio credit quality, remaining payments, volume and nature, credit culture and management, business environment or other management factors and 2) reasonable and supportable forecast of future economic conditions and collateral values. The Company performs a quarterly asset quality review which includes a review of forecasted gross charge-offs and recoveries, nonperforming assets, criticized loans, risk rating migration, delinquencies, etc. The asset quality review is performed by management and the results are used to consider a qualitative overlay to the quantitative baseline. The second qualitative adjustment noted above, economic conditions and collateral values, encompasses a one-year reasonable and supportable forecast period. The overlay adjustment for the reasonable and supportable forecast assumes an immediate reversion after the one-year forecast period to historical loss rates for the remaining life of the respective loan pool. When management deems it to be appropriate, the Company establishes a specific reserve for individually evaluated loans that do not share similar risk characteristics with the loans included in each respective loan pool. These individually evaluated loans are removed from their respective pools and typically represent collateral dependent loans but may also include other non-performing loans or troubled debt restructurings (“TDRs”). In addition, the Company individually evaluates “reasonably expected” TDRs, which are identified by the Company as a loan expected to be classified as a TDR within the next six months. Management judgment is utilized to make this determination. Allowance for Credit Losses (Held-to-Maturity Debt Securities) - For held-to-maturity (“HTM”) debt securities, the Company is required to utilize a CECL methodology to estimate expected credit losses. Substantially all of the Company’s HTM debt securities are issued by U.S. government agencies or U.S. government-sponsored enterprises. These securities carry the explicit and/or implicit guarantee of the U.S. government and have a long history of zero credit loss. See Note F "Fair Value Measurements" for more information about HTM debt securities. Allowance for Credit Losses (Available-for-Sale Debt Securities) - The impairment model for available-for-sale (“AFS”) debt securities differs from the CECL methodology applied for HTM debt securities because AFS debt securities are measured at fair value rather than amortized cost. Although ASC 326 replaced the legacy other-than-temporary impairment (“OTTI”) model with a credit loss model, it retained the fundamental nature of the legacy OTTI model. For AFS debt securities in an unrealized loss position, the Company first assesses whether it intends to sell, or it is more likely than not that it will be required to sell, the security before recovery of its amortized cost basis. If either criteria is met, the security’s amortized cost basis is written down to fair value through income. For AFS debt securities where neither of the criteria are met, the Company evaluates whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, management considers the extent to which fair value is less than amortized cost, any changes to the credit rating of the security by a rating agency, and adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the security are compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses is recorded for the credit loss, limited to the amount that the fair value is less than the amortized cost basis. Any remaining discount that has not been recorded through an allowance for credit losses is recognized in other comprehensive income. Under the new guidance, an entity may no longer consider the length of time fair value has been less than amortized cost. Changes in the allowance for credit losses are recorded as a provision (or release) for credit losses. Losses are charged against the allowance when management believes the uncollectibility of an AFS security is confirmed or when either of the criteria regarding intent or requirement to sell is met. See Note F "Fair Value Measurements" for more information about AFS debt securities. Accrued Interest Receivable - Upon adoption of ASC 326, the Company made the following elections regarding accrued interest receivable: • Presenting accrued interest receivable balances separately from their underlying instruments within the consolidated statements of financial condition. • Excluding accrued interest receivable that is included in the amortized cost of financing receivables from related disclosure requirements. • Continuing our policy to write off accrued interest receivable by reversing interest income in cases where the Company does not reasonably expect to receive payment. • Not measuring an allowance for credit losses for accrued interest receivable due to the Company’s policy of writing off uncollectible accrued interest receivable balances in a timely manner, as described above. Non-Accrual Loans - Loans are placed on non-accrual status when, in the judgment of management, the probability of collection of interest is deemed to be insufficient to warrant further accrual. When a loan is placed on non-accrual status, previously accrued but unpaid interest is deducted from interest income. The Bank does not accrue interest on loans 90 days or more past due. If payment is made on a loan so that the loan becomes less than 90 days past due, and the Bank expects full collection of principal and interest, the loan is returned to full accrual status. Any interest ultimately collected is credited to income in the period of recovery. A loan is charged-off when the loss is estimable and it is confirmed that the borrower is not expected to be able to meet contractual obligations. If a consumer loan is on non-accrual status before becoming a TDR it will stay on non-accrual status following restructuring until it has been performing for at least six months, at which point it may be moved to accrual status. If a loan is on accrual status before it becomes a TDR, and management concludes that full repayment is probable based on internal evaluation, it will remain on accrual status following restructuring. If the restructured consumer loan does not perform, it is placed on non-accrual status when it is 90 days delinquent. For commercial loans, six consecutive payments on newly restructured loan terms are required prior to returning the loan to accrual status. In some instances, after the required six consecutive payments are made, management will conclude that collection of the entire principal and interest due is still in doubt. In those instances, the loan will remain on non-accrual status. Collateral-Dependent Loans - A financial asset is considered collateral-dependent when the debtor is experiencing financial difficulty and repayment is expected to be provided substantially through the sale or operation of the collateral. For all classes of loans and leases deemed collateral-dependent, the Company elected the practical expedient to estimate expected credit losses based on the collateral’s fair value less cost to sell. In most cases, the Company records a partial charge-off to reduce the loan’s carrying value to the collateral’s fair value less cost to sell. Substantially all of the collateral consists of various types of real estate including residential properties; commercial properties such as retail centers, office buildings, and lodging; agriculture land; and vacant land. Off-balance-sheet credit exposures - The only material off-balance-sheet credit exposures are unfunded loan commitments, which had a combined balance of $3,348,654,000 and $2,738,095,000 at March 31, 2021 and September 30, 2020, respectively. The reserve for unfunded commitments is recognized as a liability (other liabilities in the consolidated statements of financial condition), with adjustments to the reserve recognized through provision for credit losses in the consolidated statements of income. The reserve for unfunded commitments represents the expected lifetime credit losses on off-balance sheet obligations such as commitments to extend credit and standby letters of credit. However, a liability is not recognized for commitments that are unconditionally cancellable by the Company. The reserve for unfunded commitments is determined by estimating future draws, including the effects of risk mitigation actions, and applying the expected loss rates on those draws. Loss rates are estimated by utilizing the same loss rates calculated for the allowance for credit losses related to the respective loan portfolio class. See Note I "Commitments and Contingencies" for more information.

New Accounting Pronouncements

New Accounting Pronouncements	6 Months Ended
	Mar. 31, 2021
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements In March 2020, the Financial Accounting Standards Board (“FASB”) issued ASU 2020-04, Reference Rate Reform (Topic 848). The amendments in this ASU provide temporary, optional guidance to ease the potential burden in accounting for reference rate reform. The ASU provides optional expedients and exceptions for applying GAAP to transactions affected by reference rate reform if certain criteria are met. The ASU primarily includes relief related to contract modifications and hedging relationships, as well as providing a one-time election for the sale or transfer of debt securities classified as held-to-maturity. This guidance is effective immediately and the amendments may be applied prospectively through December 31, 2022. The Company is currently in the process of evaluating the amendments and determining the impact to its consolidated financial statements. In August 2018, the FASB issued ASU 2018-15, Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract . The amendments in this ASU align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The amendments also require the entity to expense the capitalized implementation costs of a hosting arrangement that is a service contract over the term of the hosting arrangement, including reasonably certain renewal periods. The amendments in the ASU are effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. The Company adopted this ASU beginning October 1, 2020 and it did not have a material impact on its consolidated financial statements.

Dividends and Share Repurchases

Dividends and Share Repurchases	6 Months Ended
	Mar. 31, 2021
Stockholders' Equity Note [Abstract]
Dividends and Share Repurchases	Dividends and Share Repurchases On February 19, 2021, the Company paid a regular dividend on common stock of $0.23 per share, which represented the 152 nd consecutive quarterly cash dividend. Dividends per share were $0.23 and $0.22 for the quarters ended March 31, 2021 and 2020, respectively. On April 27, 2021, the Company declared a regular dividend on common stock of $0.23 per share, which represents its 153 rd consecutive quarterly cash dividend. This dividend will be paid on May 21, 2021 to common shareholders of record on May 7, 2021. For the three months ended March 31, 2021, the Company repurchased 2,824,588 shares at an average price of $31.53. This total includes 1,715,335 shares of common stock repurchased under the modified "Dutch auction" tender offer that was completed in March 2021 for a total cost of $53,780,000, including fees and expenses. As of March 31, 2021, there are 11,769,687 remaining shares authorized to be repurchased under the current Board approved share repurchase program. On January 26, 2021 the Board authorized an additional 10,000,000 shares for repurchase under the program. On April 2, 2021, the Company declared a cash dividend of $9.0729 per share on its Series A Preferred Stock. This dividend equals $0.22682250 per depositary share. The Series A Preferred Stock dividend was paid on April 15, 2021, to shareholders of record as of April 13, 2021.

Loans Receivable

Loans Receivable	6 Months Ended
	Mar. 31, 2021
Receivables [Abstract]
Loans Receivable	Loans Receivable For a detailed discussion of loans and credit quality, including accounting policies and the CECL methodology used to estimate the allowance for credit losses, see Note A "Summary of Significant Accounting Policies" above. The Company's loans held for investment are divided into two portfolio segments, commercial loans and consumer loans, with each of those segments further split into loan classes for purposes of estimating the allowance for credit losses. The following table is a summary of loans receivable by loan portfolio segment and class. March 31, 2021 September 30, 2020 (In thousands) (In thousands) Commercial loans Multi-family $ 2,008,192 13.2 % $ 1,538,762 10.6 % Commercial real estate 2,226,560 14.6 1,895,086 13.1 Commercial & industrial (1) 2,471,823 16.2 2,132,160 14.7 Construction 2,495,961 16.3 2,403,276 16.6 Land - acquisition & development 185,024 1.2 193,745 1.3 Total commercial loans 9,387,560 61.5 8,163,029 56.3 Consumer loans Single-family residential 4,828,535 31.6 5,304,689 36.7 Construction - custom 678,469 4.5 674,879 4.7 Land - consumer lot loans 123,351 0.8 102,263 0.7 HELOC 144,528 0.9 139,703 1.0 Consumer 103,145 0.7 83,159 0.6 Total consumer loans 5,878,028 38.5 6,304,693 43.7 Total gross loans 15,265,588 100 % 14,467,722 100 % Less: Allowance for credit losses on loans 172,653 166,955 Loans in process 1,982,225 1,456,072 Net deferred fees, costs and discounts 75,287 52,378 Total loan contra accounts 2,230,165 1,675,405 Net loans $ 13,035,423 $ 12,792,317 (1) Includes $711,405,000 and $762,004,000 of SBA Payroll Protection Program loans as of March 31, 2021 and September 30, 2020, respectively. The Company elected to exclude accrued interest receivable ("AIR") from the amortized cost basis of loans for disclosure purposes and from the calculations of estimated credit losses. As of March 31, 2021, and September 30, 2020, AIR for loans totaled $48,676,000 and $48,704,000, respectively, and is included in the “accrued interest receivable” line item on the Company’s consolidated statements of financial condition. Loans in the amount of $6,314,864,000 and $5,361,504,000 at March 31, 2021 and September 30, 2020, respectively, were pledged to secure borrowings from the Federal Home Loan Bank ("FHLB") as part of our liquidity management strategy. The FHLB does not have the right to sell or re-pledge these loans. The following table sets forth the amortized cost basis of non-accrual loans and loans 90 days or more past due and accruing. March 31, 2021 September 30, 2020 (In thousands, except ratio data) Non-accrual Non-accrual with no ACL 90 days or more past due and accruing Non-accrual Non-accrual with no ACL 90 days or more past due and accruing Commercial loans Multi-family $ — $ — $ — $ — $ — $ — Commercial real estate 9,226 — — 3,771 — — Commercial & industrial 832 — — 329 — — Construction 1,423 — — 1,669 — — Land - acquisition & development 2,340 — — — — — Total commercial loans 13,821 — — 5,769 — — Consumer loans Single-family residential 25,599 — — 22,431 — 933 Construction - custom — — — — — — Land - consumer lot loans 177 — — 243 — — HELOC 306 — — 553 — — Consumer 52 — — 60 — 17 Total consumer loans 26,134 — — 23,287 — 950 Total non-accrual loans $ 39,955 $ — $ — $ 29,056 $ — $ 950 % of total loans 0.30 % 0.22 % The Company recognized interest income on non-accrual loans of approximately $5,228,000 in the six months ended March 31, 2021. Had these loans been on accrual status and performed according to their original contract terms, the Company would have recognized interest income of approximately $769,000 for the six months ended March 31, 2021. Recognized interest income for the six months ended March 31, 2021 was higher than what otherwise would have been recognized in the period due to the collection of past due amounts. Interest cash flows collected on non-accrual loans vary from period to period as those loans are brought current or are paid off. The following tables provide details regarding loan delinquencies by loan portfolio and class. March 31, 2021 Days Delinquent Based on $ Amount of Loans % based Type of Loan Loans Receivable (Amortized Cost) Current 30 60 90 Total Delinquent (In thousands, except ratio data) Commercial Loans Multi-family $ 1,987,120 $ 1,986,645 $ — $ 475 $ — $ 475 0.02 % Commercial real estate 2,211,065 2,206,097 37 111 4,820 4,968 0.22 Commercial & industrial 2,452,585 2,450,623 1,175 — 787 1,962 0.08 Construction 925,017 923,864 — — 1,153 1,153 0.12 Land - acquisition & development 150,311 147,971 — — 2,340 2,340 1.56 Total commercial loans 7,726,098 7,715,200 1,212 586 9,100 10,898 0.14 Consumer Loans Single-family residential 4,802,575 4,776,367 5,868 960 19,380 26,208 0.55 Construction - custom 308,831 308,831 — — — — — Land - consumer lot loans 122,211 121,858 93 185 75 353 0.29 HELOC 145,066 144,667 118 — 281 399 0.28 Consumer 103,294 102,979 174 2 139 315 0.30 Total consumer loans 5,481,977 5,454,702 6,253 1,147 19,875 27,275 0.50 Total Loans $ 13,208,075 $ 13,169,902 $ 7,465 $ 1,733 $ 28,975 $ 38,173 0.29 % Delinquency % 99.71% 0.06% 0.01% 0.22% 0.29% September 30, 2020 Days Delinquent Based on $ Amount of Loans % based Type of Loan Loans Receivable (Amortized Cost) Current 30 60 90 Total Delinquent (In thousands, except ratio data) Commercial Loans Multi-family $ 1,538,240 $ 1,538,240 $ — $ — $ — $ — — % Commercial real estate 1,884,688 1,884,210 — 195 283 478 0.03 Commercial & industrial 2,115,513 2,114,650 — 583 280 863 0.04 Construction 1,352,414 1,350,752 — — 1,662 1,662 0.12 Land - acquisition & development 153,571 153,571 — — — — — Total commercial loans 7,044,426 7,041,423 — 778 2,225 3,003 0.04 Consumer Loans Single-family residential 5,293,962 5,267,608 3,922 3,108 19,324 26,354 0.50 Construction - custom 295,953 295,953 — — — — — Land - consumer lot loans 101,394 101,029 152 — 213 365 0.36 HELOC 140,222 139,491 275 76 380 731 0.52 Consumer 83,315 82,959 121 11 224 356 0.43 Total consumer loans 5,914,846 5,887,040 4,470 3,195 20,141 27,806 0.47 Total Loans $ 12,959,272 $ 12,928,463 $ 4,470 $ 3,973 $ 22,366 $ 30,809 0.24 % Delinquency % 99.76% 0.03% 0.03% 0.17% 0.24% The Company participated in the Small Business Administration’s Paycheck Protection Program ("PPP"). This program came about through the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) passed by Congress to help small businesses keep their employees employed through the COVID-19 shelter in place orders. In 2020, the Company assisted over 6,500 businesses with more than $780,000,000 in PPP loans. Fiscal 2021 year to date we have assisted over 2,000 small businesses with $235,000,000 in PPP loans. The Company has actively worked with its borrowers to modify consumer mortgage and commercial loans to provide payment deferrals as a result of the COVID-19 pandemic. The terms of the payment deferrals are generally 90 days for consumer mortgage loans and up to 180 days for commercial loans and borrowers may be eligible for multiple deferrals. Pursuant to the CARES Act, these loan modifications are not accounted for as TDRs. As of March 31, 2021, 45 mortgage loans totaling $14,000,000 and 10 commercial loans totaling $89,000,000 that had been modified remain in deferral. These loans are not considered past due until after the deferral period is over and scheduled payments have resumed. Most TDRs are accruing and performing loans where the borrower has proactively approached the Company about modification due to temporary financial difficulties. Each request for modification is individually evaluated for merit and likelihood of success. The concession granted in a loan modification is typically a payment reduction through a rate reduction of between 100 to 200 basis points for a specific term, usually six We evaluate the credit quality of our loans based on regulatory risk ratings and also consider other factors. Based on this evaluation, the loans are assigned a grade and classified as follows: • Pass – the credit does not meet one of the definitions below. • Special mention – A special mention credit is considered to be currently protected from loss but is potentially weak. No loss of principal or interest is foreseen; however, proper supervision and management attention is required to deter further deterioration in the credit. Assets in this category constitute some undue and unwarranted credit risk but not to the point of justifying a risk rating of substandard. The credit risk may be relatively minor yet constitutes an unwarranted risk in light of the circumstances surrounding a specific asset. • Substandard – A substandard credit is an unacceptable credit. Additionally, repayment in the normal course is in jeopardy due to the existence of one or more well defined weaknesses. In these situations, loss of principal is likely if the weakness is not corrected. A substandard asset is inadequately protected by the current sound worth and paying capacity of the borrower or of the collateral pledged, if any. Assets so classified will have a well-defined weakness or weaknesses that jeopardize the collection or liquidation of the debt. Loss potential, while existing in the aggregate amount of substandard assets, does not have to exist in individual assets risk rated substandard. • Doubtful – A credit classified doubtful has all the weaknesses inherent in one classified substandard with the added characteristic that the weakness makes collection or liquidation in full, on the basis of currently existing facts, conditions and values, highly questionable and improbable. The probability of loss is high, but because of certain important and reasonably specific pending factors that may work to the advantage and strengthening of the asset, its classification as an estimated loss is deferred until its more exact status may be determined. Pending factors include proposed merger, acquisition, or liquidation procedures, capital injection, perfecting liens on additional collateral, and refinancing plans. • Loss – Credits classified loss are considered uncollectible and of such little value that their continuance as a bankable asset is not warranted. This classification does not mean that the asset has absolutely no recovery or salvage value, but rather it is not practical or desirable to defer writing off this asset even though partial recovery may be affected in the future. Losses should be taken in the period in which they are identified as uncollectible. Partial charge-off versus full charge-off may be taken if the collateral offers some identifiable protection. The following tables present by primary credit quality indicator, loan class, and year of origination, the amortized cost basis of loans receivable as of March 31, 2021. Term Loans Amortized Cost Basis by Origination Year YTD 2021 2020 2019 2018 2017 Prior to 2017 Revolving Loans Revolving to Term Loans Total Loans Commercial loans Multi-family Pass $ 267,297 $ 507,301 $ 248,237 $ 295,532 $ 247,043 $ 344,441 $ 8,221 $ — $ 1,918,072 Special Mention — 1,769 — 4,039 2,844 1,934 — — 10,586 Substandard — — 7,546 651 3,746 46,519 — — 58,462 Total $ 267,297 $ 509,070 $ 255,783 $ 300,222 $ 253,633 $ 392,894 $ 8,221 $ — $ 1,987,120 Commercial real estate Pass $ 252,949 $ 443,877 $ 282,617 $ 274,651 $ 240,058 $ 440,678 $ 2,203 $ — $ 1,937,033 Special Mention — 194 4,432 33,380 1,697 23,144 — — 62,847 Substandard — 9,012 69,855 22,619 47,503 62,196 — — 211,185 Total $ 252,949 $ 453,083 $ 356,904 $ 330,650 $ 289,258 $ 526,018 $ 2,203 $ — $ 2,211,065 Commercial & industrial Pass $ 547,764 $ 631,137 $ 57,479 $ 52,576 $ 78,044 $ 159,841 $ 635,066 $ 11,944 $ 2,173,851 Special Mention — 9,798 6,785 630 18 — 31,636 — 48,867 Substandard 12,363 48,216 4,126 6,443 94 48,126 110,227 272 229,867 Total $ 560,127 $ 689,151 $ 68,390 $ 59,649 $ 78,156 $ 207,967 $ 776,929 $ 12,216 $ 2,452,585 Construction Pass $ 136,932 $ 311,836 $ 270,277 $ 67,312 $ — $ — $ 94,845 $ — $ 881,202 Substandard — 4,321 2,348 — 37,146 — — — 43,815 Total $ 136,932 $ 316,157 $ 272,625 $ 67,312 $ 37,146 $ — $ 94,845 $ — $ 925,017 Land - acquisition & development Pass $ 22,127 $ 39,505 $ 28,645 $ 18,007 $ 14,789 $ 4,011 $ 5,314 $ — $ 132,398 Special Mention — — — — — 15,573 — — 15,573 Substandard — — — — 2,340 — — — 2,340 Total $ 22,127 $ 39,505 $ 28,645 $ 18,007 $ 17,129 $ 19,584 $ 5,314 $ — $ 150,311 Total commercial loans Pass $ 1,227,069 $ 1,933,656 $ 887,255 $ 708,078 $ 579,934 $ 948,971 $ 745,649 $ 11,944 $ 7,042,556 Special Mention — 11,761 11,217 38,049 4,559 40,651 31,636 — 137,873 Substandard 12,363 61,549 83,875 29,713 90,829 156,841 110,227 272 545,669 Total $ 1,239,432 $ 2,006,966 $ 982,347 $ 775,840 $ 675,322 $ 1,146,463 $ 887,512 $ 12,216 $ 7,726,098 Term Loans Amortized Cost Basis by Origination Year YTD 2021 2020 2019 2018 2017 Prior to 2017 Revolving Loans Revolving to Term Loans Total Loans Consumer loans Single-family residential Current $ 499,799 $ 825,204 $ 512,811 $ 458,566 $ 514,115 $ 1,965,872 $ — $ — $ 4,776,367 30 days past due — — — 115 — 5,753 — — 5,868 60 days past due — — — — — 960 — — 960 90+ days past due — — — 466 169 18,745 — — 19,380 Total $ 499,799 $ 825,204 $ 512,811 $ 459,147 $ 514,284 $ 1,991,330 $ — $ — $ 4,802,575 Construction - custom Current $ 50,146 $ 242,667 $ 14,955 $ 1,063 $ — $ — $ — $ — $ 308,831 Total $ 50,146 $ 242,667 $ 14,955 $ 1,063 $ — $ — $ — $ — $ 308,831 Land - consumer lot loans Current $ 41,526 $ 35,849 $ 13,856 $ 5,304 $ 6,565 $ 18,758 $ — $ — $ 121,858 30 days past due — — — — — 93 — — 93 60 days past due — — — 185 — — — — 185 90+ days past due — — — — — 75 — — 75 Total $ 41,526 $ 35,849 $ 13,856 $ 5,489 $ 6,565 $ 18,926 $ — $ — $ 122,211 HELOC Current $ — $ — $ — $ — $ — $ 5,917 $ 137,531 $ 1,219 $ 144,667 30 days past due — — — — — 93 25 — 118 90+ days past due — — — — — 30 251 — 281 Total $ — $ — $ — $ — $ — $ 6,040 $ 137,807 $ 1,219 $ 145,066 Consumer Current $ 10,891 $ 8,245 $ 1,011 $ 45,983 $ — $ 14,000 $ 22,849 $ — $ 102,979 30 days past due — — 5 — 75 94 — — 174 60 days past due — — 2 — — — — — 2 90+ days past due — — 37 — 96 6 — — 139 Total $ 10,891 $ 8,245 $ 1,055 $ 45,983 $ 171 $ 14,100 $ 22,849 $ — $ 103,294 Total consumer loans Current $ 602,362 $ 1,111,965 $ 542,633 $ 510,916 $ 520,680 $ 2,004,547 $ 160,380 $ 1,219 $ 5,454,702 30 days past due — — 5 115 75 6,033 25 — 6,253 60 days past due — — 2 185 — 960 — — 1,147 90+ days past due — — 37 466 265 18,856 251 — 19,875 Total $ 602,362 $ 1,111,965 $ 542,677 $ 511,682 $ 521,020 $ 2,030,396 $ 160,656 $ 1,219 $ 5,481,977

Allowance for Losses on Loans

Allowance for Losses on Loans	6 Months Ended
	Mar. 31, 2021
Receivables [Abstract]
Allowance for Losses on Loans	Allowance for Losses on Loans For a detailed discussion of loans and credit quality, including accounting policies and the CECL methodology used to estimate the allowance for credit losses, see Note A "Summary of Significant Accounting Policies." The following tables summarize the activity in the allowance for loan losses by loan portfolio segment and class. Three Months Ended March 31, 2021 Beginning Allowance Charge-offs Recoveries Provision & Ending Allowance (In thousands) Commercial loans Multi-family $ 14,363 $ — $ — $ 3,413 $ 17,776 Commercial real estate 23,496 — 1,457 1,869 26,822 Commercial & industrial 44,317 (18) 11 3,484 47,794 Construction 26,365 — — (3,816) 22,549 Land - acquisition & development 10,666 — 410 (573) 10,503 Total commercial loans 119,207 (18) 1,878 4,377 125,444 Consumer loans Single-family residential 38,613 (106) 497 (3,896) 35,108 Construction - custom 3,594 — — (346) 3,248 Land - consumer lot loans 2,958 — 7 327 3,292 HELOC 2,362 — — (136) 2,226 Consumer 3,455 (84) 290 (326) 3,335 Total consumer loans 50,982 (190) 794 (4,377) 47,209 Total loans $ 170,189 $ (208) $ 2,672 $ — $ 172,653 Three Months Ended March 31, 2020 Beginning Allowance Charge-offs Recoveries Provision & Transfers (1) Ending Allowance (In thousands) Commercial loans Multi-family $ 10,506 $ — $ — $ 1,236 $ 11,742 Commercial real estate 13,067 (13) 1,020 565 14,639 Commercial & industrial 33,676 (129) 57 4,972 38,576 Construction 21,919 — 5 1,424 23,348 Land - acquisition & development 10,413 — 126 (140) 10,399 Total commercial loans 89,581 (142) 1,208 8,057 98,704 Consumer loans Single-family residential 46,356 — 192 268 46,816 Construction - custom 2,930 — — 245 3,175 Land - consumer lot loans 2,567 (77) 476 (388) 2,578 HELOC 2,034 — 1 211 2,246 Consumer 4,045 (230) 360 (593) 3,582 Total consumer loans 57,932 (307) 1,029 (257) 58,397 Total loans $ 147,513 $ (449) $ 2,237 $ 7,800 $ 157,101 (1) Provision & transfer amounts within the table do not include the provision for unfunded commitments of $400,000 Six Months Ended March 31, 2021 Beginning Allowance Charge-offs Recoveries Provision & Transfers (1) Ending Allowance (In thousands) Commercial loans Multi-family $ 13,853 $ — $ — $ 3,923 $ 17,776 Commercial real estate 22,516 — 2,246 2,060 26,822 Commercial & industrial 38,665 (20) 61 9,088 47,794 Construction 24,156 — — (1,607) 22,549 Land - acquisition & development 10,733 — 445 (675) 10,503 Total commercial loans 109,923 (20) 2,752 12,789 125,444 Consumer loans Single-family residential 45,186 (106) 1,276 (11,248) 35,108 Construction - custom 3,555 — — (307) 3,248 Land - consumer lot loans 2,729 — 14 549 3,292 HELOC 2,571 — — (345) 2,226 Consumer 2,991 (234) 516 62 3,335 Total consumer loans 57,032 (340) 1,806 (11,289) 47,209 Total loans $ 166,955 $ (360) $ 4,558 $ 1,500 $ 172,653 (1) Provision & transfer amounts within the table do not include the provision for unfunded commitments of $1,500,000 Six Months Ended March 31, 2020 Beginning Allowance Charge-offs Recoveries Provision & Transfers (1) Ending Allowance (In thousands) Commercial loans Multi-family $ 10,404 $ — $ 498 $ 840 $ 11,742 Commercial real estate 13,024 (111) 1,388 338 14,639 Commercial & industrial 32,235 (179) 201 6,319 38,576 Construction 22,768 — 59 521 23,348 Land - acquisition & development 10,904 (11) 1,586 (2,080) 10,399 Total commercial loans 89,335 (301) 3,732 5,938 98,704 Consumer loans Single-family residential 47,771 (15) 453 (1,393) 46,816 Construction - custom 2,880 — — 295 3,175 Land - consumer lot loans 2,635 (147) 486 (396) 2,578 HELOC 2,048 — 94 104 2,246 Consumer 4,615 (604) 669 (1,098) 3,582 Total consumer loans 59,949 (766) 1,702 (2,488) 58,397 Total loans $ 149,284 $ (1,067) $ 5,434 $ 3,450 $ 157,101 (1) Provision & transfer amounts within the table do not include the provision for unfunded commitments of $1,000,000 The Company recorded no provision for credit losses for the three months ended March 31, 2021, compared with a provision for credit losses of $8,200,000 for the three months ended March 31, 2020. The relatively large credit loss provision for the three months ended March 31, 2020 is primarily due to the onset of the global pandemic. The Company recorded a provision for credit losses of $3,000,000 for the six months ended March 31, 2021, compared with a provision for credit losses of $4,450,000 for the six months ended March 31, 2020. Recoveries, net of charge-offs, totaled $2,464,000 for the three months ended March 31, 2021, compared to net recoveries of $1,788,000 during the three months ended March 31, 2020. Recoveries, net of charge-offs, totaled $4,198,000 for the six months ended March 31, 2021, compared to net recoveries of $4,367,000 during the six months ended March 31, 2020. No allowance was recorded as of March 31, 2021 or as of September 30, 2020 for the $695,752,000 and $745,081,000 of PPP loans in the portfolio on each date, respectively, which are included in the commercial & industrial loan category, due to the government guarantee. Non-performing assets were $48,943,000, or 0.25% of total assets, at March 31, 2021, compared to $37,695,000, or 0.20% of total assets, at September 30, 2020. Non-accrual loans were $39,955,000 at March 31, 2021, compared to $29,056,000 at September 30, 2020. Delinquencies, as a percent of total loans, were 0.29% at March 31, 2021, compared to 0.24% at September 30, 2020. The Company has an asset quality review function that analyzes its loan portfolio and reports the results of the review to its Board of Directors on a quarterly basis. The single-family residential, HELOC and consumer portfolios are evaluated based on their performance as a pool of loans, since no single loan is individually significant or judged by its risk rating, size or potential risk of loss. The construction, land, multi-family, commercial real estate and commercial and industrial loans are risk rated on a loan by loan basis to determine the relative risk inherent in specific borrowers or loans. Based on that risk rating, the loans are assigned a grade and classified as described in Note D "Loans Receivable." The following tables provide the amortized cost of loans receivable based on risk rating categories as previously defined. March 31, 2021 Internally Assigned Grade Pass Special mention Substandard Doubtful Loss Total (In thousands, except ratio data) Loan type Commercial loans Multi-family $ 1,918,072 $ 10,586 $ 58,462 $ — $ — $ 1,987,120 Commercial real estate 1,937,033 62,847 211,185 — — 2,211,065 Commercial & industrial 2,173,851 48,867 229,867 — — 2,452,585 Construction 881,202 — 43,815 — — 925,017 Land - acquisition & development 132,398 15,573 2,340 — — 150,311 Total commercial loans 7,042,556 137,873 545,669 — — 7,726,098 Consumer loans Single-family residential 4,773,261 189 29,125 — — 4,802,575 Construction - custom 308,831 — — — — 308,831 Land - consumer lot loans 122,034 — 177 — — 122,211 HELOC 143,167 — 1,899 — — 145,066 Consumer 103,274 — 20 — — 103,294 Total consumer loans 5,450,567 189 31,221 — — 5,481,977 Total $ 12,493,123 $ 138,062 $ 576,890 $ — $ — $ 13,208,075 Total grade as a % of total loans 94.59 % 1.05 % 4.37 % — % — % September 30, 2020 Internally Assigned Grade Pass Special mention Substandard Doubtful Loss Total Gross Loans (In thousands, except ratio data) Loan type Commercial loans Multi-family $ 1,506,692 $ 13,721 $ 17,827 $ — $ — $ 1,538,240 Commercial real estate 1,681,230 92,184 111,274 — — 1,884,688 Commercial & industrial 1,898,709 64,695 152,109 — — 2,115,513 Construction 1,187,786 61,178 103,450 — — 1,352,414 Land - acquisition & development 137,998 15,573 — — — 153,571 Total commercial loans 6,412,415 247,351 384,660 — — 7,044,426 Consumer loans Single-family residential 5,270,666 192 23,104 — — 5,293,962 Construction - custom 295,953 — — — — 295,953 Land - consumer lot loans 101,151 — 243 — — 101,394 HELOC 139,646 — 576 — — 140,222 Consumer 83,304 — 11 — — 83,315 Total consumer loans 5,890,720 192 23,934 — — 5,914,846 Total loans $ 12,303,135 $ 247,543 $ 408,594 $ — $ — $ 12,959,272 Total grade as a % of total gross loans 94.94 % 1.91 % 3.15 % — % — % The following tables provide information on amortized cost of loans receivable based on borrower payment activity. March 31, 2021 Performing Loans Non-Performing Loans Amount % of Total Amount % of Total (In thousands, except ratio data) Commercial loans Multi-family $ 1,987,120 100.0 % $ — — % Commercial real estate 2,201,839 99.6 9,226 0.4 Commercial & industrial 2,451,753 100.0 832 — Construction 923,594 99.8 1,423 0.2 Land - acquisition & development 147,971 98.4 2,340 1.6 Total commercial loans 7,712,277 99.8 13,821 0.2 Consumer loans Single-family residential 4,776,976 99.5 25,599 0.5 Construction - custom 308,831 100.0 — — Land - consumer lot loans 122,034 99.9 177 0.1 HELOC 144,760 99.8 306 0.2 Consumer 103,242 99.9 52 0.1 Total consumer loans 5,455,843 99.5 26,134 0.5 Total loans $ 13,168,120 99.7 % $ 39,955 0.3 % September 30, 2020 Performing Loans Non-Performing Loans Amount % of Total Amount % of Total (In thousands, except ratio data) Commercial loans Multi-family $ 1,538,240 100.0 % $ — — % Commercial real estate 1,880,917 99.8 3,771 0.2 Commercial & industrial 2,115,184 100.0 329 — Construction 1,350,745 99.9 1,669 0.1 Land - acquisition & development 153,571 100.0 — — Total commercial loans 7,038,657 99.9 5,769 0.1 Consumer loans Single-family residential 5,271,531 99.6 22,431 0.4 Construction - custom 295,953 100.0 — — Land - consumer lot loans 101,151 99.8 243 0.2 HELOC 139,669 99.6 553 0.4 Consumer 83,255 99.9 60 0.1 Total consumer loans 5,891,559 99.6 23,287 0.4 Total loans $ 12,930,216 99.8 % $ 29,056 0.2 %

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements FASB ASC 820, Fair Value Measurement ("ASC 820") defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. ASC 820 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 standard describes three levels of inputs that may be used to measure fair value: Level 1: Quoted prices (unadjusted) for identical assets or liabilities in active exchange markets that the entity has the ability to access as of the measurement date. Level 2: Significant other observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active and other inputs that are observable or can be corroborated by observable market data. Level 3: Significant unobservable inputs that reflect a company’s own assumptions about the assumptions that market participants would use in pricing an asset or liability. The Company has established and documented the process for determining the fair values of its assets and liabilities, where applicable. Fair value is based on quoted market prices, when available, for identical or similar assets or liabilities. In the absence of quoted market prices, fair value is determined using valuation models or third-party appraisals. The following is a description of the valuation methodologies used to measure and report the fair value of financial assets and liabilities on a recurring or nonrecurring basis. Measured on a Recurring Basis Available-for-Sale Securities and Derivative Contracts Securities available for sale are recorded at fair value on a recurring basis. The fair value of debt securities are priced using model pricing based on the securities' relationship to other benchmark quoted prices as provided by an independent third party, and under GAAP are considered a Level 2 input method. Securities that are traded on active exchanges are measured using the closing price in an active market and are considered a Level 1 input method. The Company offers interest rate swaps to its variable rate borrowers who want to manage their interest rate risk. At the same time, the Company enters into the opposite trade with a counter party to offset its interest rate risk. The Company has also entered into commercial loan hedges, mortgage pool hedges and borrowings hedges using interest rate swaps. The fair value of these interest rate swaps are estimated by a third party pricing service using a discounted cash flow technique. These are considered a Level 2 input method. The following tables present the balance and level in the fair value hierarchy of assets and liabilities that are measured at fair value on a recurring basis. March 31, 2021 Level 1 Level 2 Level 3 Total (In thousands) Financial Assets Available-for-sale securities: U.S. government and agency securities $ — $ 71,512 $ — $ 71,512 Asset-backed securities — 1,183,977 — 1,183,977 Municipal bonds — 38,669 — 38,669 Corporate debt securities — 380,115 — 380,115 Mortgage-backed securities Agency pass-through certificates — 764,629 — 764,629 Total available-for-sale securities — 2,438,902 — 2,438,902 Client swap program hedges — 5,104 — 5,104 Mortgage loan fair value hedges — 2,135 — 2,135 Borrowings cash flow hedges — 59,198 — 59,198 Total financial assets $ — $ 2,505,339 $ — $ 2,505,339 Financial Liabilities Client swap program hedges $ — $ 5,104 $ — $ 5,104 Commercial loan fair value hedges — 4,610 — 4,610 Total financial liabilities $ — $ 9,714 $ — $ 9,714 September 30, 2020 Level 1 Level 2 Level 3 Total (In thousands) Financial Assets Available-for-sale securities: U.S. government and agency securities $ — $ 18,824 $ — $ 18,824 Asset-backed securities — 936,917 936,917 Municipal bonds — 38,315 — 38,315 Corporate debt securities — 287,184 — 287,184 Mortgage-backed securities Agency pass-through certificates — 968,252 — 968,252 Total available-for-sale securities — 2,249,492 — 2,249,492 Client swap program hedges — 48,201 — 48,201 Total financial assets $ — $ 2,297,693 $ — $ 2,297,693 Financial Liabilities Client swap program hedges $ — $ 48,201 $ — $ 48,201 Commercial loan fair value hedges — 8,492 — 8,492 Mortgage loan fair value hedges 16,061 16,061 Borrowings cash flow hedges — 17,375 — 17,375 Total financial liabilities $ — $ 90,129 $ — $ 90,129 Measured on a Nonrecurring Basis Certain assets and liabilities are measured at fair value on a nonrecurring basis after initial recognition such as collateral dependent loans and real estate owned ("REO"). REO consists principally of properties acquired through foreclosure. From time to time, and on a nonrecurring basis, adjustments using fair value measurements are recorded to reflect increases or decreases based on the discounted cash flows, the current appraisal or estimated value of the collateral or REO property. When management determines that the fair value of the collateral or the REO requires additional adjustments, either as a result of an updated appraised value or when there is no observable market price, the Company classifies the collateral dependent loan or real estate owned as Level 3. Level 3 assets recorded at fair value on a nonrecurring basis at March 31, 2021 included loans for which an allowance was established or a partial charge-off was recorded based on the fair value of collateral, as well as real estate owned where the fair value of the property was less than the cost basis. The following tables present the aggregated balance of assets that were measured at fair value on a nonrecurring basis at March 31, 2021 and March 31, 2020, and the total gains (losses) resulting from those fair value adjustments during the respective periods. The estimated fair value measurements are shown gross of estimated selling costs. March 31, 2021 Three Months Ended March 31, 2021 Six Months Ended March 31, 2021 Level 1 Level 2 Level 3 Total Total Gains (Losses) (In thousands) (In thousands) Loans (1) $ — $ — $ — $ — $ (25) $ (69) Real estate owned (2) — — 722 722 148 101 Balance at end of period $ — $ — $ 722 $ 722 $ 123 $ 32 (1) The gains (losses) represent re-measurements of collateral-dependent loans. (2) The gains (losses) represent aggregate write-downs and charge-offs on real estate owned. March 31, 2020 Three Months Ended March 31, 2020 Six Months Ended March 31, 2020 Level 1 Level 2 Level 3 Total Total Gains (Losses) (In thousands) (In thousands) Loans (1) $ — $ — $ 810 $ 810 $ (246) $ (545) Real estate owned (2) — — 1,675 1,675 145 143 Balance at end of period $ — $ — $ 2,485 $ 2,485 $ (101) $ (402) (1) The gains (losses) represent re-measurements of collateral-dependent loans. (2) The gains (losses) represent aggregate write-downs and charge-offs on real estate owned. At March 31, 2021, there were $676,000 in foreclosed residential real estate properties held as REO. The recorded investment of consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings were in process was $3,134,000. Fair Values of Financial Instruments FASB ASC 825, Financial Instruments ("ASC 825") requires disclosure of fair value information about financial instruments, whether or not recognized on the statement of financial condition, for which it is practicable to estimate those values. Certain financial instruments and all non-financial instruments are excluded from the disclosure requirements. Accordingly, the aggregate fair value estimates presented do not reflect the underlying fair value of the Company. Although management is not aware of any factors that would materially affect the estimated fair value amounts presented below, such amounts have not been comprehensively revalued for purposes of these financial statements since the dates shown, and therefore, estimates of fair value subsequent to those dates may differ significantly from the amounts presented below. March 31, 2021 September 30, 2020 Level in Fair Value Hierarchy Carrying Estimated Carrying Estimated ($ in thousands) Financial assets Cash and cash equivalents 1 $ 2,318,447 $ 2,318,447 $ 1,702,977 $ 1,702,977 Available-for-sale securities U.S. government and agency securities 2 71,512 71,512 18,824 18,824 Asset-backed securities 2 1,183,977 1,183,977 936,917 936,917 Municipal bonds 2 38,669 38,669 38,315 38,315 Corporate debt securities 2 380,115 380,115 287,184 287,184 Mortgage-backed securities Agency pass-through certificates 2 764,629 764,629 968,252 968,252 Total available-for-sale securities 2,438,902 2,438,902 2,249,492 2,249,492 Held-to-maturity securities Mortgage-backed securities Agency pass-through certificates 2 489,915 503,723 698,934 720,516 Commercial MBS 2 4,174 4,174 6,904 6,852 Total held-to-maturity securities 494,089 507,897 705,838 727,368 Loans receivable 3 13,035,423 13,419,101 12,792,317 13,392,089 FHLB and FRB stock 2 119,991 119,991 141,990 141,990 Other assets - client swap program hedges 2 5,104 5,104 48,201 48,201 Other assets - commercial fair value loan hedges 2 — — — — Other assets - mortgage loan fair value hedges 2 2,135 2,135 — — Other assets - borrowings cash flow hedges 2 59,198 59,198 — — Financial liabilities Time deposits 2 3,590,755 3,543,588 3,973,192 3,963,203 FHLB advances 2 2,150,000 2,115,171 2,700,000 2,722,509 Other liabilities - client swap program hedges 2 5,104 5,104 48,201 48,201 Other liabilities - commercial loan fair value hedges 2 4,610 4,610 8,492 8,492 Other liabilities - mortgage loan fair value hedges 2 — — 16,061 16,061 Other liabilities - borrowings cash flow hedges 2 — — 17,375 17,375 The following methods and assumptions were used to estimate the fair value of financial instruments: Cash and cash equivalents – The carrying amount of these items is a reasonable estimate of their fair value. Available-for-sale securities and held-to-maturity securities – Securities at fair value are primarily priced using model pricing based on the securities' relationship to other benchmark quoted prices as provided by an independent third party, and are considered a Level 2 input method. Equity securities that are exchange traded are considered a Level 1 input method. Loans receivable – Fair values are estimated first by stratifying the portfolios of loans with similar financial characteristics. Loans are segregated by type such as multi-family real estate, residential mortgage, construction, commercial, consumer and land loans. Each loan category is further segmented into fixed- and adjustable-rate interest terms. For residential mortgages and multi-family loans, the bank determined that its best exit price was by securitization. MBS benchmark prices are used as a base price, with further loan level pricing adjustments made based on individual loan characteristics such as FICO score, LTV, Property Type and occupancy. For all other loan categories an estimate of fair value is then calculated based on discounted cash flows using a discount rate offered and observed in the market on similar products, plus an adjustment for liquidity to reflect the non-homogeneous nature of the loans, as well as an annual loss rate based on historical losses to arrive at an estimated exit price fair value. Fair value for impaired loans is also based on recent appraisals or estimated cash flows discounted using rates commensurate with risk associated with the estimated cash flows. Assumptions regarding credit risk, cash flows and discount rates are judgmentally determined using available market information and specific borrower information. FHLB and FRB stock – The fair value is based upon the par value of the stock that equates to its carrying value. Time deposits – The fair value of time deposits is estimated by discounting the estimated future cash flows using rates offered for deposits with similar remaining maturities. FHLB advances – The fair value of FHLB advances and other borrowings is estimated by discounting the estimated future cash flows using rates currently available to the Company for debt with similar remaining maturities. Interest rate swaps – The Company offers interest rate swaps to its variable rate borrowers who want to manage their interest rate risk. At the same time, the Company enters into the opposite trade with a counterparty to offset its interest rate risk. The Company also uses interest rate swaps for various fair value hedges and cash flow hedges. The fair value of these interest rate swaps is estimated by a third party pricing service using a discounted cash flow technique. The following tables provide details about the amortized cost and fair value of available-for-sale and held-to-maturity securities. March 31, 2021 Amortized Gross Unrealized Fair Yield Gains Losses ($ in thousands) Available-for-sale securities U.S. government and agency securities due 1 to 5 years $ 54,992 $ 516 $ — $ 55,508 0.50 % 5 to 10 years 15,897 107 — 16,004 2.05 Asset-backed securities 5 to 10 years 102,141 447 (718) 101,870 0.68 Over 10 years 1,071,530 10,994 (417) 1,082,107 1.07 Corporate debt securities due Within 1 year 31,742 126 (28) 31,840 1.98 1 to 5 years 195,442 7,120 — 202,562 1.67 5 to 10 years 65,888 751 (710) 65,929 3.14 Over 10 years 80,560 — (776) 79,784 3.44 Municipal bonds due 1 to 5 years 1,477 28 — 1,505 — 5 to 10 years 5,797 275 — 6,072 0.27 Over 10 years 29,929 1,163 — 31,092 5.85 Mortgage-backed securities Agency pass-through certificates 737,281 29,622 (2,274) 764,629 2.67 2,392,676 51,149 (4,923) 2,438,902 1.80 Held-to-maturity securities Mortgage-backed securities Agency pass-through certificates 489,915 13,808 — 503,723 3.16 Commercial MBS 4,174 — — 4,174 0.98 494,089 13,808 — 507,897 3.14 $ 2,886,765 $ 64,957 $ (4,923) $ 2,946,799 2.02 % September 30, 2020 Amortized Gross Unrealized Fair Yield Gains Losses ($ in thousands) Available-for-sale securities U.S. government and agency securities due 5 to 10 years $ 18,448 $ 376 $ — $ 18,824 2.05 % Asset-backed securities 5 to 10 years 38,289 — (1,600) 36,689 0.83 Over 10 years 906,489 647 (6,908) 900,228 1.14 Corporate debt securities due Within 1 year 54,209 337 (51) 54,495 1.22 1 to 5 years 128,289 3,366 (428) 131,227 1.78 5 to 10 years 97,157 4,305 — 101,462 1.50 Municipal bonds due 1 to 5 years 1,461 36 — 1,497 — Over 10 years 36,044 774 — 36,818 5.40 Mortgage-backed securities Agency pass-through certificates 929,713 39,166 (627) 968,252 2.82 2,210,099 49,007 (9,614) 2,249,492 1.97 Held-to-maturity securities Mortgage-backed securities Agency pass-through certificates 698,934 21,582 — 720,516 3.16 Commercial MBS 6,904 — (52) 6,852 1.02 705,838 21,582 (52) 727,368 3.14 $ 2,915,937 $ 70,589 $ (9,666) $ 2,976,860 2.25 % During fiscal 2020, as permitted in conjunction with the adoption of ASU 2019-04, the Company reclassified $374,680,000 of prepayable debt securities from held-to-maturity to available-for-sale. For available-for-sale investment securities, there were purchases of $522,454,000 during the six months ended March 31, 2021 and purchases of $159,884,000 during the six months ended March 31, 2020. There were no sales of available-for-sale investment securities during the six months ended March 31, 2021 and sales totaled $204,351,000 during the prior year same period. For held-to-maturity investment securities, there were no purchases during the six months ended March 31, 2021 and no purchases during the six months ended March 31, 2020. There were no sales of held-to-maturity investment securities during either period. Substantially all of the agency mortgage-backed securities have contractual due dates that exceed 10 years. The Company elected to exclude AIR from the amortized cost basis of debt securities disclosed throughout this footnote. For AFS securities, AIR totaled $4,128,000 and $3,285,000 as of March 31, 2021 and September 30, 2020, respectively. For HTM debt securities, AIR totaled $1,269,000 and $1,811,000 as of March 31, 2021 and September 30, 2020, respectively. AIR is included in the “accrued interest receivable” line item on the Company’s consolidated statements of financial condition. The following tables show the gross unrealized losses and fair value of securities as of March 31, 2021 and September 30, 2020, by length of time that individual securities in each category have been in a continuous loss position. There were 38 and 51 securities with an unrealized loss as of March 31, 2021 and September 30, 2020, respectively. The decline in fair value since purchase is attributable to changes in interest rates. Because the Company does not intend to sell these securities and does not consider it more likely than not that it will be required to sell these securities before the recovery of amortized cost basis, which may be upon maturity, the Company does not consider these investments to have any credit impairment. March 31, 2021 Less than 12 months 12 months or more Total Unrealized Fair Unrealized Fair Unrealized Fair (In thousands) Available-for-sale securities Corporate debt securities $ (1,514) $ 125,191 $ — $ — $ (1,514) $ 125,191 Asset-backed securities (77) 80,046 (1,058) 125,681 (1,135) 205,727 Mortgage-backed securities (1,963) 55,679 (311) 31,951 (2,274) 87,630 (3,554) 260,916 (1,369) 157,632 (4,923) 418,548 Held-to-maturity securities Mortgage-backed securities — — — — — — $ (3,554) $ 260,916 $ (1,369) $ 157,632 $ (4,923) $ 418,548 September 30, 2020 Less than 12 months 12 months or more Total Unrealized Fair Unrealized Fair Unrealized Fair (In thousands) Available-for-sale securities Corporate debt securities $ (74) $ 45,875 $ (405) $ 24,596 $ (479) $ 70,471 Asset-backed securities (5,481) 587,746 (3,027) 204,369 (8,508) 792,115 Mortgage-backed securities (278) 41,897 (349) 56,196 (627) 98,093 (5,833) 675,518 (3,781) 285,161 (9,614) 960,679 Held-to-maturity securities Mortgage-backed securities (52) 6,853 — — (52) 6,853 $ (5,885) $ 682,371 $ (3,781) $ 285,161 $ (9,666) $ 967,532 Substantially all of the Company’s held-to-maturity debt securities are issued by U.S. government agencies or U.S. government-sponsored enterprises. These securities carry the explicit and/or implicit guarantee of the U.S. government and have a long history of zero credit loss. Therefore, the Company did not record an allowance for credit losses for these securities as of March 31, 2021 or September 30, 2020. The Company does not believe that the available-for-sale debt securities that were in an unrealized loss position have any credit loss impairment as of March 31, 2021 or September 30, 2020. The Company does not intend to sell the investment securities that were in an unrealized loss position and it is not more likely than not that the Company will be required to sell the investment securities before recovery of their amortized cost basis, which may be at maturity. Available-for-sale debt securities issued by U.S. government agencies or U.S. government-sponsored enterprises carry the explicit and/or implicit guarantee of the U.S. government and have a long history of zero credit loss. Corporate debt securities and municipal bonds are considered to have an issuer of high credit quality (rated AA or higher) and the decline in fair value is due to changes in interest rates and other market conditions. The issuer continues to make timely principal and interest payments on the bonds. The fair value is expected to recover as the bonds approach maturity.

Derivatives and Hedging Activit

Derivatives and Hedging Activities	6 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Hedging Activities	Derivatives and Hedging Activities The following tables present the fair value, notional amount and balance sheet classification of derivative assets and liabilities at March 31, 2021 and September 30, 2020. March 31, 2021 Derivative Assets Derivative Liabilities Interest rate contract purpose Balance Sheet Location Notional Fair Value Balance Sheet Location Notional Fair Value (In thousands) (In thousands) Client swap program hedges Other assets $ 653,904 $ 5,104 Other liabilities $ 653,904 $ 5,104 Commercial loan fair value hedges Other assets — — Other liabilities 90,918 4,610 Mortgage loan fair value hedges Other assets 500,000 2,135 Other liabilities — — Borrowings cash flow hedges Other assets 1,200,000 59,198 Other liabilities — — $ 2,353,904 $ 66,437 $ 744,822 $ 9,714 September 30, 2020 Derivative Assets Derivative Liabilities Interest rate contract purpose Balance Sheet Location Notional Fair Value Balance Sheet Location Notional Fair Value (In thousands) (In thousands) Client swap program hedges Other assets $ 656,074 $ 48,201 Other liabilities $ 656,074 $ 48,201 Commercial loan fair value hedges Other assets — — Other liabilities 93,316 8,492 Mortgage loan fair value hedges Other assets — — Other liabilities 500,000 16,061 Borrowings cash flow hedges Other assets — — Other liabilities 1,600,000 17,375 $ 656,074 $ 48,201 $ 2,849,390 $ 90,129 The Company enters into interest rate swaps to hedge interest rate risk. These arrangements include hedges of individual fixed rate commercial loans and also hedges of a specified portion of pools of prepayable fixed rate mortgage loans under the "last of layer" method. These relationships qualify as fair value hedges under FASB ASC 815, Derivatives and Hedging ("ASC 815"), which provides for offsetting of the recognition of gains and losses of the respective interest rate swap and the hedged items. Gains and losses on interest rate swaps designated in these hedge relationships, along with the offsetting gains and losses on the hedged items attributable to the hedged risk, are recognized in current earnings within the same income statement line item. Upon electing to apply ASC 815 fair value hedge accounting, the carrying value of the hedged item is adjusted to reflect the cumulative impact of changes in fair value attributable to the hedged risk. The hedge basis adjustment remains with the hedged item until the hedged item is de-recognized from the balance sheet. The following tables present the impact of fair value hedge accounting on the carrying value of the hedged items at March 31, 2021 and September 30, 2020. (In thousands) March 31, 2021 Balance sheet line item in which hedged item is recorded Carrying value of hedged items Cumulative gain (loss) fair value hedge adjustment included in carrying amount of hedged items Loans receivable (1) (2) $ 1,934,688 $ 2,831 $ 1,934,688 $ 2,831 (1) Includes the amortized cost basis of the closed mortgage loan portfolios used to designate the hedging relationships in which the hedged items are the last layer expected to be remaining at the end of the hedging relationships. At March 31, 2021, the amortized cost basis of the closed loan portfolios used in the hedging relationships was $1,839,169,000, the cumulative basis adjustment associated with the hedging relationships was $(1,929,000), and the amount of the designated hedged items was $500,000,000. (2) Includes the amortized cost basis of commercial loans designated in fair value hedging relationships. At March 31, 2021, the amortized cost basis of the hedged commercial loans was $95,519,000 and the cumulative basis adjustment associated with the hedging relationships was $4,760,000. (In thousands) September 30, 2020 Balance sheet line item in which hedged item is recorded Carrying value of hedged items Cumulative gain (loss) fair value hedge adjustment included in carrying amount of hedged items Loans receivable (1) (2) $ 2,562,765 $ 24,664 $ 2,562,765 $ 24,664 (1) Includes the amortized cost basis of the closed mortgage loan portfolios used to designate the hedging relationships in which the hedged items are the last layer expected to be remaining at the end of the hedging relationships. At September 30, 2020, the amortized cost basis of the closed loan portfolios used in the hedging relationships was $2,461,008,000, the cumulative basis adjustment associated with the hedging relationships was $16,049,000, and the amount of the designated hedged items was $500,000,000. (2) Includes the amortized cost basis of commercial loans designated in fair value hedging relationships. At September 30, 2020, the amortized cost basis of the hedged commercial loans was $101,757,000 and the cumulative basis adjustment associated with the hedging relationships was $8,615,000. The Company has entered into interest rate swaps to convert certain short-term borrowings to fixed rate payments. The primary purpose of these hedges is to mitigate the risk of changes in future cash flows resulting from increasing interest rates. For qualifying cash flow hedges under ASC 815, gains and losses on the interest rate swaps are recorded in accumulated other comprehensive income ("AOCI") and then reclassified into earnings in the same period the hedged cash flows affect earnings and within the same income statement line item as the hedged cash flows. During the six months ended March 31, 2021, $200,000,000 of cash flow hedges with an average effective rate of 1.37% were terminated and the associated FHLB borrowings were repaid at their 90-day call date. Additionally, a $200,000,000 partial termination of a cash flow hedge with an average effective rate of 0.79% was executed with the associated FHLB borrowing being repaid and a $14,110,000 gain recorded on the swap. Lastly, a $150,000,000 FHLB borrowing (unhedged) with a rate of 2.91% was repaid prior to maturity. As of March 31, 2021, the maturities for hedges of adjustable rate borrowings ranged from less than one year to ten years, with the weighted average being 6.7 years. The following tables present the gain (loss) recognized in AOCI on derivative instruments related to cash flow hedges on borrowings for the periods presented, as well as the effect of reclassification adjustments. (In thousands) Three Months Ended March 31, Amounts recognized in AOCI 2021 2020 Interest rate contracts: Pay fixed/receive floating swaps on borrowings cash flow hedges $ 70,565 $ (12,428) Reclassification adjustment of net (gain)/loss included in net income (14,110) — Total pre-tax gain/(loss) recognized in AOCI $ 56,455 $ (12,428) (In thousands) Six Months Ended March 31, Amounts recognized in AOCI 2021 2020 Interest rate contracts: Pay fixed/receive floating swaps on borrowings cash flow hedges $ 90,683 $ (9,313) Reclassification adjustment of net (gain)/loss included in net income (14,110) — Total pre-tax gain/(loss) recognized in AOCI $ 76,573 $ (9,313) The following tables present the gain (loss) on derivative instruments in fair value and cash flow accounting hedging relationships under ASC 815 for the periods presented. Three Months Ended March 31, 2021 Three Months Ended March 31, 2020 Interest income on loans receivable Interest expense on FHLB advances Interest income on loans receivable Interest expense on FHLB advances (In thousands) (In thousands) Interest income/(expense), including the effects of fair value and cash flow hedges $ 132,757 $ (11,991) $ 138,549 $ (13,368) Gain/(loss) on fair value hedging relationships: Interest rate contracts Amounts related to interest settlements on derivatives $ (1,563) $ (112) Recognized on derivatives 17,491 (24,676) Recognized on hedged items (17,377) 24,666 Net income/(expense) recognized on fair value hedges $ (1,449) $ (122) Gain/(loss) on cash flow hedging relationships: Interest rate contracts Amounts related to interest settlements on derivatives $ 3,066 $ 498 Amount of derivative gain/(loss) reclassified from AOCI into interest income/expense 14,110 — Net income/(expense) recognized on cash flow hedges $ 17,176 $ 498 Six months ended March 31, 2021 Six months ended March 31, 2020 Interest income on loans receivable Interest expense on FHLB advances Interest income on loans receivable Interest expense on FHLB advances (In thousands) (In thousands) Interest income/(expense), including the effects of fair value and cash flow hedges $ 266,428 $ (25,189) $ 280,695 $ (27,026) Gain/(loss) on fair value hedging relationships: Interest rate contracts Amounts related to interest settlements on derivatives $ (3,104) $ (186) Recognized on derivatives 22,078 (19,984) Recognized on hedged items (21,833) 20,073 Net income/(expense) recognized on fair value hedges $ (2,859) $ (97) Gain/(loss) on cash flow hedging relationships: Interest rate contracts Amounts related to interest settlements on derivatives $ 6,664 $ 284 Amount of derivative gain/(loss) reclassified from AOCI into interest income/expense 14,110 — Net income/(expense) recognized on cash flow hedges $ 20,774 $ 284 The Company periodically enters into certain interest rate swap agreements in order to provide commercial loan customers the ability to convert from variable to fixed interest rate payments, while the Company retains a variable rate loan. Under these agreements, the Company enters into a variable rate loan agreement and a swap agreement with the client. The swap agreement effectively converts the client’s variable rate loan into a fixed rate. The Company enters into a corresponding swap agreement with a third party in order to offset its exposure on the variable and fixed components of the client's swap agreement. The interest rate swaps are derivatives under ASC 815, with changes in fair value recorded in earnings. There was no net impact to the statement of operations for the six months ended March 31, 2021 and 2020 as the changes in fair value of the receive fixed swap and pay fixed swap offset each other. The following tables present the impact of derivative instruments (client swap program) that are not designated in accounting hedges under ASC 815 for the periods presented. (In thousands) Three Months Ended March 31, Derivative instruments Classification of gain/(loss) recognized in income on derivative instrument 2021 2020 Interest rate contracts: Pay fixed/receive floating swap Other noninterest income $ 40,929 $ (28,184) Receive fixed/pay floating swap Other noninterest income (40,929) 28,184 $ — $ —

Revenue from Contracts with Cus

Revenue from Contracts with Customers	6 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	Revenue from Contracts with Customers Since net interest income on financial assets and liabilities is outside the scope of ASU No. 2014-09, Revenue from Contracts with Customers ("ASC 606"), a significant majority of our revenues are not subject to that guidance. Revenue streams that are within the scope of ASC 606 are presented within non-interest income and are, in general, recognized as revenue at the same time the Company's obligation to the customer is satisfied. Most of the Company's customer contracts that are within the scope of the new guidance are cancelable by either party without penalty and are short-term in nature. These sources of revenue include depositor and other consumer and business banking fees, commission income, as well as debit and credit card interchange fees. In scope revenue streams represented approximately 5.7% of our total revenues for the six months ended March 31, 2021, compared to 4.7% for the six months ended March 31, 2020. As this standard is immaterial to our consolidated financial statements, the Company has omitted certain disclosures in ASC 606, including the disaggregation of revenue table. Sources of non-interest income within the scope of the guidance include the following: Deposit related and other service charges (recognized in Deposit fee income) - The Company's deposit accounts are governed by standardized contracts customary in the industry. Revenues are earned at a point in time or over time (monthly) from account maintenance fees and charges for specific transactions such as wire transfers, stop payment orders, overdrafts, debit card replacements, check orders and cashier’s checks. The Company’s performance obligation related to each of these fees is generally satisfied, and the related revenue recognized, at the time the service is provided (point in time or monthly). The Company is principal in each of these contracts. Debit and Credit Card Interchange Fees (recognized in Deposit fee income) - The Company receives interchange fees from the debit card or credit card payment network based on transactions involving debit or credit cards issued by the Company, generally measured as a percentage of the underlying transaction. Interchange fees from debit and credit card transactions are recognized as the transaction processing services are provided by the network. The Company acts as an agent in the card payment network arrangement so the interchange fees are recorded net of any expenses paid to the principal (the card payment network in this case).

Commitment and Contingencies

Commitment and Contingencies	6 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Commitments - The Company’s lease commitments consist primarily of real estate property for branches and office space under various non-cancellable operating leases that expire between 2021 and 2070. The majority of the leases contain renewal options and provisions for increases in rental rates based on a predetermined schedule or an agreed upon index. Financial Instruments with Off-Balance Sheet Risk - The only material off-balance-sheet credit exposures are loans in process and unused lines of credit, which had a combined balance of $3,348,654,000 and $2,738,095,000 at March 31, 2021 and September 30, 2020, respectively. The reserve was $26,500,000 as of March 31, 2021, which is an increase from $25,000,000 at September 30, 2020. See Note A "Summary of Significant Accounting Policies" for details regarding the reserve methodology. Legal Proceedings - The Company and its subsidiaries are from time to time defendants in and are threatened with various legal proceedings arising from regular business activities. Management, after consulting with legal counsel, is of the opinion that the ultimate liability, if any, resulting from these pending or threatened actions and proceedings will not have a material effect on the financial statements of the Company.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation - The Company has prepared the consolidated unaudited interim financial statements included in this report. All intercompany transactions and accounts have been eliminated in consolidation. The preparation of financial statements, in conformity with accounting principles generally accepted in the United States of America (“GAAP”), requires management to make estimates and assumptions that affect amounts reported in the financial statements. Actual results could differ from these estimates. In the opinion of management, all adjustments (consisting only of normal recurring adjustments) necessary for a fair presentation are reflected in the interim financial statements. The information included in this Form 10-Q should be read in conjunction with the financial statements and related notes in the Company's 2020 Annual Report on Form 10-K filed with the Securities and Exchange Commission ("SEC") on November 23, 2020 ("2020 Annual Financial Statements"). Interim results are not necessarily indicative of results for a full year.
Equity Securities	Equity Securities - The Company records equity securities within Other assets in its Consolidated Statements of Financial Condition. Investments in equity securities with readily determinable fair values (marketable) are measured at fair value, with
Allowance for Credit Losses (Loans Receivable)	Allowance for Credit Losses (Loans Receivable) - Effective October 1, 2019, the Company has applied ASC 326 for the periods presented herein , so the allowance calculation is based on current expected credit loss methodology ("CECL"). Prior to October 1, 2019, the calculation was based on incurred loss methodology. The Company maintains an allowance for credit losses (“ACL”) for the expected credit losses of the loan portfolio as well as unfunded loan commitments. The amount of ACL is based on ongoing, quarterly assessments by management. The CECL methodology requires an estimate of the credit losses expected over the life of an exposure (or pool of exposures) and replaces the incurred loss methodology’s threshold that delayed the recognition of a credit loss until it was probable a loss event was incurred. The ACL consists of the allowance for loan losses and the reserve for unfunded commitments. The estimate of expected credit losses under the CECL methodology is based on relevant information about past events, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amounts. Historical loss experience is generally the starting point for estimating expected credit losses. We then consider whether the historical loss experience should be adjusted for asset-specific risk characteristics or current conditions at the reporting date that did not exist over the period that historical experience was based for each loan type. Finally, we consider forecasts about future economic conditions or changes in collateral values that are reasonable and supportable. Portfolio segment is defined as the level at which an entity develops and documents a systematic methodology to determine its ACL. The Company has designated two loan portfolio segments, commercial loans and consumer loans. These loan portfolio segments are further disaggregated into classes, which represent loans of similar type, risk characteristics, and methods for monitoring and assessing credit risk. The commercial loan portfolio segment is disaggregated into five classes: multi-family, commercial real estate, commercial and industrial, construction, and land acquisition and development. The risk of loss for the commercial loan portfolio segment is generally most indicated by the credit risk rating assigned to each borrower. Commercial loan risk ratings are determined by experienced senior credit officers based on specific facts and circumstances and are subject to periodic review by an independent internal team of credit specialists. The consumer loan portfolio segment is disaggregated into five classes: single-family-residential mortgage, custom construction, consumer lot loans, home equity lines of credit, and other consumer. The risk of loss for the consumer loan portfolio segment is generally most indicated by delinquency status and general economic factors. Each commercial and consumer loan portfolio class may also be further segmented based on risk characteristics. For most of our loan portfolio classes, the historical loss experience is determined using a cohort methodology. This method pools loans into groups (“cohorts”) sharing similar risk characteristics and tracks each cohort’s net charge-offs over the lives of the loans to calculate a historical loss rate. The historical loss rates for each cohort are then averaged to calculate an overall historical loss rate which is applied to the current loan balance to arrive at the quantitative baseline portion of the allowance for credit losses for the respective loan portfolio class. For certain loan portfolio classes, the Company determined there was not sufficient historical loss information to calculate a meaningful historical loss rate using the cohort methodology. For any such loan portfolio class, the weighted-average remaining maturity (“WARM”) methodology is being utilized until sufficient historical loss data is obtained. The WARM method multiplies an average annual loss rate by the expected remaining life of the loan pool to arrive at the quantitative baseline portion of the allowance for credit losses for the respective loan portfolio class. The Company also considers qualitative adjustments to the historical loss rate for each loan portfolio class. The qualitative adjustments for each loan class consider the conditions over the period from which historical loss experience was based and are split into two components: 1) asset or class specific risk characteristics or current conditions at the reporting date related to portfolio credit quality, remaining payments, volume and nature, credit culture and management, business environment or other management factors and 2) reasonable and supportable forecast of future economic conditions and collateral values. The Company performs a quarterly asset quality review which includes a review of forecasted gross charge-offs and recoveries, nonperforming assets, criticized loans, risk rating migration, delinquencies, etc. The asset quality review is performed by management and the results are used to consider a qualitative overlay to the quantitative baseline. The second qualitative adjustment noted above, economic conditions and collateral values, encompasses a one-year reasonable and supportable forecast period. The overlay adjustment for the reasonable and supportable forecast assumes an immediate reversion after the one-year forecast period to historical loss rates for the remaining life of the respective loan pool. When management deems it to be appropriate, the Company establishes a specific reserve for individually evaluated loans that do not share similar risk characteristics with the loans included in each respective loan pool. These individually evaluated loans are removed from their respective pools and typically represent collateral dependent loans but may also include other non-performing loans or troubled debt restructurings (“TDRs”). In addition, the Company individually evaluates “reasonably expected” TDRs, which are identified by the Company as a loan expected to be classified as a TDR within the next six months. Management judgment is utilized to make this determination.
Allowance for Credit Losses (Held-to-Maturity and Available-for-Sale Debt Securities)	Allowance for Credit Losses (Held-to-Maturity Debt Securities) - For held-to-maturity (“HTM”) debt securities, the Company is required to utilize a CECL methodology to estimate expected credit losses. Substantially all of the Company’s HTM debt securities are issued by U.S. government agencies or U.S. government-sponsored enterprises. These securities carry the explicit and/or implicit guarantee of the U.S. government and have a long history of zero credit loss. See Note F "Fair Value Measurements" for more information about HTM debt securities.
Accrued Interest Receivable	Accrued Interest Receivable - Upon adoption of ASC 326, the Company made the following elections regarding accrued interest receivable: • Presenting accrued interest receivable balances separately from their underlying instruments within the consolidated statements of financial condition. • Excluding accrued interest receivable that is included in the amortized cost of financing receivables from related disclosure requirements. • Continuing our policy to write off accrued interest receivable by reversing interest income in cases where the Company does not reasonably expect to receive payment. • Not measuring an allowance for credit losses for accrued interest receivable due to the Company’s policy of writing off uncollectible accrued interest receivable balances in a timely manner, as described above.
Non-Accrual and Collateral-Dependent Loans	Non-Accrual Loans - Loans are placed on non-accrual status when, in the judgment of management, the probability of collection of interest is deemed to be insufficient to warrant further accrual. When a loan is placed on non-accrual status, previously accrued but unpaid interest is deducted from interest income. The Bank does not accrue interest on loans 90 days or more past due. If payment is made on a loan so that the loan becomes less than 90 days past due, and the Bank expects full collection of principal and interest, the loan is returned to full accrual status. Any interest ultimately collected is credited to income in the period of recovery. A loan is charged-off when the loss is estimable and it is confirmed that the borrower is not expected to be able to meet contractual obligations. If a consumer loan is on non-accrual status before becoming a TDR it will stay on non-accrual status following restructuring until it has been performing for at least six months, at which point it may be moved to accrual status. If a loan is on accrual status before it becomes a TDR, and management concludes that full repayment is probable based on internal evaluation, it will remain on accrual status following restructuring. If the restructured consumer loan does not perform, it is placed on non-accrual status when it is 90 days delinquent. For commercial loans, six consecutive payments on newly restructured loan terms are required prior to returning the loan to accrual status. In some instances, after the required six consecutive payments are made, management will conclude that collection of the entire principal and interest due is still in doubt. In those instances, the loan will remain on non-accrual status. Collateral-Dependent Loans - A financial asset is considered collateral-dependent when the debtor is experiencing financial difficulty and repayment is expected to be provided substantially through the sale or operation of the collateral. For all classes of loans and leases deemed collateral-dependent, the Company elected the practical expedient to estimate expected credit losses based on the collateral’s fair value less cost to sell. In most cases, the Company records a partial charge-off to reduce the loan’s carrying value to the collateral’s fair value less cost to sell. Substantially all of the collateral consists of various types of real estate including residential properties; commercial properties such as retail centers, office buildings, and lodging; agriculture land; and vacant land.
Off-balance-sheet credit exposures	The reserve for unfunded commitments is recognized as a liability (other liabilities in the consolidated statements of financial condition), with adjustments to the reserve recognized through provision for credit losses in the consolidated statements of income. The reserve for unfunded commitments represents the expected lifetime credit losses on off-balance sheet obligations such as commitments to extend credit and standby letters of credit. However, a liability is not recognized for commitments that are unconditionally cancellable by the Company. The reserve for unfunded commitments is determined by estimating future draws, including the effects of risk mitigation actions, and applying the expected loss rates on those draws. Loss rates are estimated by utilizing the same loss rates calculated for the allowance for credit losses related to the respective loan portfolio class. See Note I "Commitments and Contingencies" for more information.
New Accounting Pronouncements	In March 2020, the Financial Accounting Standards Board (“FASB”) issued ASU 2020-04, Reference Rate Reform (Topic 848). The amendments in this ASU provide temporary, optional guidance to ease the potential burden in accounting for reference rate reform. The ASU provides optional expedients and exceptions for applying GAAP to transactions affected by reference rate reform if certain criteria are met. The ASU primarily includes relief related to contract modifications and hedging relationships, as well as providing a one-time election for the sale or transfer of debt securities classified as held-to-maturity. This guidance is effective immediately and the amendments may be applied prospectively through December 31, 2022. The Company is currently in the process of evaluating the amendments and determining the impact to its consolidated financial statements. In August 2018, the FASB issued ASU 2018-15, Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract . The amendments in this ASU align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The amendments also require the entity to expense the capitalized implementation costs of a hosting arrangement that is a service contract over the term of the hosting arrangement, including reasonably certain renewal periods. The amendments in the ASU are effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. The Company adopted this ASU beginning October 1, 2020 and it did not have a material impact on its consolidated financial statements.
Fair Value Measurements	FASB ASC 820, Fair Value Measurement ("ASC 820") defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. ASC 820 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 standard describes three levels of inputs that may be used to measure fair value: Level 1: Quoted prices (unadjusted) for identical assets or liabilities in active exchange markets that the entity has the ability to access as of the measurement date. Level 2: Significant other observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active and other inputs that are observable or can be corroborated by observable market data. Level 3: Significant unobservable inputs that reflect a company’s own assumptions about the assumptions that market participants would use in pricing an asset or liability. The Company has established and documented the process for determining the fair values of its assets and liabilities, where applicable. Fair value is based on quoted market prices, when available, for identical or similar assets or liabilities. In the absence of quoted market prices, fair value is determined using valuation models or third-party appraisals. The following is a description of the valuation methodologies used to measure and report the fair value of financial assets and liabilities on a recurring or nonrecurring basis. Measured on a Recurring Basis Available-for-Sale Securities and Derivative Contracts Securities available for sale are recorded at fair value on a recurring basis. The fair value of debt securities are priced using model pricing based on the securities' relationship to other benchmark quoted prices as provided by an independent third party, and under GAAP are considered a Level 2 input method. Securities that are traded on active exchanges are measured using the closing price in an active market and are considered a Level 1 input method. The Company offers interest rate swaps to its variable rate borrowers who want to manage their interest rate risk. At the same time, the Company enters into the opposite trade with a counter party to offset its interest rate risk. The Company has also entered into commercial loan hedges, mortgage pool hedges and borrowings hedges using interest rate swaps. The fair value of these interest rate swaps are estimated by a third party pricing service using a discounted cash flow technique. These are considered a Level 2 input method.

Loans Receivable (Tables)

Loans Receivable (Tables)	6 Months Ended
	Mar. 31, 2021
Receivables [Abstract]
Schedule of Loans Receivable	The following table is a summary of loans receivable by loan portfolio segment and class. March 31, 2021 September 30, 2020 (In thousands) (In thousands) Commercial loans Multi-family $ 2,008,192 13.2 % $ 1,538,762 10.6 % Commercial real estate 2,226,560 14.6 1,895,086 13.1 Commercial & industrial (1) 2,471,823 16.2 2,132,160 14.7 Construction 2,495,961 16.3 2,403,276 16.6 Land - acquisition & development 185,024 1.2 193,745 1.3 Total commercial loans 9,387,560 61.5 8,163,029 56.3 Consumer loans Single-family residential 4,828,535 31.6 5,304,689 36.7 Construction - custom 678,469 4.5 674,879 4.7 Land - consumer lot loans 123,351 0.8 102,263 0.7 HELOC 144,528 0.9 139,703 1.0 Consumer 103,145 0.7 83,159 0.6 Total consumer loans 5,878,028 38.5 6,304,693 43.7 Total gross loans 15,265,588 100 % 14,467,722 100 % Less: Allowance for credit losses on loans 172,653 166,955 Loans in process 1,982,225 1,456,072 Net deferred fees, costs and discounts 75,287 52,378 Total loan contra accounts 2,230,165 1,675,405 Net loans $ 13,035,423 $ 12,792,317
Non-accrual Loans and Loans 90 Days or More Past Due and Accruing	The following table sets forth the amortized cost basis of non-accrual loans and loans 90 days or more past due and accruing. March 31, 2021 September 30, 2020 (In thousands, except ratio data) Non-accrual Non-accrual with no ACL 90 days or more past due and accruing Non-accrual Non-accrual with no ACL 90 days or more past due and accruing Commercial loans Multi-family $ — $ — $ — $ — $ — $ — Commercial real estate 9,226 — — 3,771 — — Commercial & industrial 832 — — 329 — — Construction 1,423 — — 1,669 — — Land - acquisition & development 2,340 — — — — — Total commercial loans 13,821 — — 5,769 — — Consumer loans Single-family residential 25,599 — — 22,431 — 933 Construction - custom — — — — — — Land - consumer lot loans 177 — — 243 — — HELOC 306 — — 553 — — Consumer 52 — — 60 — 17 Total consumer loans 26,134 — — 23,287 — 950 Total non-accrual loans $ 39,955 $ — $ — $ 29,056 $ — $ 950 % of total loans 0.30 % 0.22 %
Loan Delinquencies by Loan Portfolio and Class	The following tables provide details regarding loan delinquencies by loan portfolio and class. March 31, 2021 Days Delinquent Based on $ Amount of Loans % based Type of Loan Loans Receivable (Amortized Cost) Current 30 60 90 Total Delinquent (In thousands, except ratio data) Commercial Loans Multi-family $ 1,987,120 $ 1,986,645 $ — $ 475 $ — $ 475 0.02 % Commercial real estate 2,211,065 2,206,097 37 111 4,820 4,968 0.22 Commercial & industrial 2,452,585 2,450,623 1,175 — 787 1,962 0.08 Construction 925,017 923,864 — — 1,153 1,153 0.12 Land - acquisition & development 150,311 147,971 — — 2,340 2,340 1.56 Total commercial loans 7,726,098 7,715,200 1,212 586 9,100 10,898 0.14 Consumer Loans Single-family residential 4,802,575 4,776,367 5,868 960 19,380 26,208 0.55 Construction - custom 308,831 308,831 — — — — — Land - consumer lot loans 122,211 121,858 93 185 75 353 0.29 HELOC 145,066 144,667 118 — 281 399 0.28 Consumer 103,294 102,979 174 2 139 315 0.30 Total consumer loans 5,481,977 5,454,702 6,253 1,147 19,875 27,275 0.50 Total Loans $ 13,208,075 $ 13,169,902 $ 7,465 $ 1,733 $ 28,975 $ 38,173 0.29 % Delinquency % 99.71% 0.06% 0.01% 0.22% 0.29% September 30, 2020 Days Delinquent Based on $ Amount of Loans % based Type of Loan Loans Receivable (Amortized Cost) Current 30 60 90 Total Delinquent (In thousands, except ratio data) Commercial Loans Multi-family $ 1,538,240 $ 1,538,240 $ — $ — $ — $ — — % Commercial real estate 1,884,688 1,884,210 — 195 283 478 0.03 Commercial & industrial 2,115,513 2,114,650 — 583 280 863 0.04 Construction 1,352,414 1,350,752 — — 1,662 1,662 0.12 Land - acquisition & development 153,571 153,571 — — — — — Total commercial loans 7,044,426 7,041,423 — 778 2,225 3,003 0.04 Consumer Loans Single-family residential 5,293,962 5,267,608 3,922 3,108 19,324 26,354 0.50 Construction - custom 295,953 295,953 — — — — — Land - consumer lot loans 101,394 101,029 152 — 213 365 0.36 HELOC 140,222 139,491 275 76 380 731 0.52 Consumer 83,315 82,959 121 11 224 356 0.43 Total consumer loans 5,914,846 5,887,040 4,470 3,195 20,141 27,806 0.47 Total Loans $ 12,959,272 $ 12,928,463 $ 4,470 $ 3,973 $ 22,366 $ 30,809 0.24 % Delinquency % 99.76% 0.03% 0.03% 0.17% 0.24%
Summary of Loans Based on Credit Quality Indicators	The following tables present by primary credit quality indicator, loan class, and year of origination, the amortized cost basis of loans receivable as of March 31, 2021. Term Loans Amortized Cost Basis by Origination Year YTD 2021 2020 2019 2018 2017 Prior to 2017 Revolving Loans Revolving to Term Loans Total Loans Commercial loans Multi-family Pass $ 267,297 $ 507,301 $ 248,237 $ 295,532 $ 247,043 $ 344,441 $ 8,221 $ — $ 1,918,072 Special Mention — 1,769 — 4,039 2,844 1,934 — — 10,586 Substandard — — 7,546 651 3,746 46,519 — — 58,462 Total $ 267,297 $ 509,070 $ 255,783 $ 300,222 $ 253,633 $ 392,894 $ 8,221 $ — $ 1,987,120 Commercial real estate Pass $ 252,949 $ 443,877 $ 282,617 $ 274,651 $ 240,058 $ 440,678 $ 2,203 $ — $ 1,937,033 Special Mention — 194 4,432 33,380 1,697 23,144 — — 62,847 Substandard — 9,012 69,855 22,619 47,503 62,196 — — 211,185 Total $ 252,949 $ 453,083 $ 356,904 $ 330,650 $ 289,258 $ 526,018 $ 2,203 $ — $ 2,211,065 Commercial & industrial Pass $ 547,764 $ 631,137 $ 57,479 $ 52,576 $ 78,044 $ 159,841 $ 635,066 $ 11,944 $ 2,173,851 Special Mention — 9,798 6,785 630 18 — 31,636 — 48,867 Substandard 12,363 48,216 4,126 6,443 94 48,126 110,227 272 229,867 Total $ 560,127 $ 689,151 $ 68,390 $ 59,649 $ 78,156 $ 207,967 $ 776,929 $ 12,216 $ 2,452,585 Construction Pass $ 136,932 $ 311,836 $ 270,277 $ 67,312 $ — $ — $ 94,845 $ — $ 881,202 Substandard — 4,321 2,348 — 37,146 — — — 43,815 Total $ 136,932 $ 316,157 $ 272,625 $ 67,312 $ 37,146 $ — $ 94,845 $ — $ 925,017 Land - acquisition & development Pass $ 22,127 $ 39,505 $ 28,645 $ 18,007 $ 14,789 $ 4,011 $ 5,314 $ — $ 132,398 Special Mention — — — — — 15,573 — — 15,573 Substandard — — — — 2,340 — — — 2,340 Total $ 22,127 $ 39,505 $ 28,645 $ 18,007 $ 17,129 $ 19,584 $ 5,314 $ — $ 150,311 Total commercial loans Pass $ 1,227,069 $ 1,933,656 $ 887,255 $ 708,078 $ 579,934 $ 948,971 $ 745,649 $ 11,944 $ 7,042,556 Special Mention — 11,761 11,217 38,049 4,559 40,651 31,636 — 137,873 Substandard 12,363 61,549 83,875 29,713 90,829 156,841 110,227 272 545,669 Total $ 1,239,432 $ 2,006,966 $ 982,347 $ 775,840 $ 675,322 $ 1,146,463 $ 887,512 $ 12,216 $ 7,726,098 Term Loans Amortized Cost Basis by Origination Year YTD 2021 2020 2019 2018 2017 Prior to 2017 Revolving Loans Revolving to Term Loans Total Loans Consumer loans Single-family residential Current $ 499,799 $ 825,204 $ 512,811 $ 458,566 $ 514,115 $ 1,965,872 $ — $ — $ 4,776,367 30 days past due — — — 115 — 5,753 — — 5,868 60 days past due — — — — — 960 — — 960 90+ days past due — — — 466 169 18,745 — — 19,380 Total $ 499,799 $ 825,204 $ 512,811 $ 459,147 $ 514,284 $ 1,991,330 $ — $ — $ 4,802,575 Construction - custom Current $ 50,146 $ 242,667 $ 14,955 $ 1,063 $ — $ — $ — $ — $ 308,831 Total $ 50,146 $ 242,667 $ 14,955 $ 1,063 $ — $ — $ — $ — $ 308,831 Land - consumer lot loans Current $ 41,526 $ 35,849 $ 13,856 $ 5,304 $ 6,565 $ 18,758 $ — $ — $ 121,858 30 days past due — — — — — 93 — — 93 60 days past due — — — 185 — — — — 185 90+ days past due — — — — — 75 — — 75 Total $ 41,526 $ 35,849 $ 13,856 $ 5,489 $ 6,565 $ 18,926 $ — $ — $ 122,211 HELOC Current $ — $ — $ — $ — $ — $ 5,917 $ 137,531 $ 1,219 $ 144,667 30 days past due — — — — — 93 25 — 118 90+ days past due — — — — — 30 251 — 281 Total $ — $ — $ — $ — $ — $ 6,040 $ 137,807 $ 1,219 $ 145,066 Consumer Current $ 10,891 $ 8,245 $ 1,011 $ 45,983 $ — $ 14,000 $ 22,849 $ — $ 102,979 30 days past due — — 5 — 75 94 — — 174 60 days past due — — 2 — — — — — 2 90+ days past due — — 37 — 96 6 — — 139 Total $ 10,891 $ 8,245 $ 1,055 $ 45,983 $ 171 $ 14,100 $ 22,849 $ — $ 103,294 Total consumer loans Current $ 602,362 $ 1,111,965 $ 542,633 $ 510,916 $ 520,680 $ 2,004,547 $ 160,380 $ 1,219 $ 5,454,702 30 days past due — — 5 115 75 6,033 25 — 6,253 60 days past due — — 2 185 — 960 — — 1,147 90+ days past due — — 37 466 265 18,856 251 — 19,875 Total $ 602,362 $ 1,111,965 $ 542,677 $ 511,682 $ 521,020 $ 2,030,396 $ 160,656 $ 1,219 $ 5,481,977 The following tables provide the amortized cost of loans receivable based on risk rating categories as previously defined. March 31, 2021 Internally Assigned Grade Pass Special mention Substandard Doubtful Loss Total (In thousands, except ratio data) Loan type Commercial loans Multi-family $ 1,918,072 $ 10,586 $ 58,462 $ — $ — $ 1,987,120 Commercial real estate 1,937,033 62,847 211,185 — — 2,211,065 Commercial & industrial 2,173,851 48,867 229,867 — — 2,452,585 Construction 881,202 — 43,815 — — 925,017 Land - acquisition & development 132,398 15,573 2,340 — — 150,311 Total commercial loans 7,042,556 137,873 545,669 — — 7,726,098 Consumer loans Single-family residential 4,773,261 189 29,125 — — 4,802,575 Construction - custom 308,831 — — — — 308,831 Land - consumer lot loans 122,034 — 177 — — 122,211 HELOC 143,167 — 1,899 — — 145,066 Consumer 103,274 — 20 — — 103,294 Total consumer loans 5,450,567 189 31,221 — — 5,481,977 Total $ 12,493,123 $ 138,062 $ 576,890 $ — $ — $ 13,208,075 Total grade as a % of total loans 94.59 % 1.05 % 4.37 % — % — % September 30, 2020 Internally Assigned Grade Pass Special mention Substandard Doubtful Loss Total Gross Loans (In thousands, except ratio data) Loan type Commercial loans Multi-family $ 1,506,692 $ 13,721 $ 17,827 $ — $ — $ 1,538,240 Commercial real estate 1,681,230 92,184 111,274 — — 1,884,688 Commercial & industrial 1,898,709 64,695 152,109 — — 2,115,513 Construction 1,187,786 61,178 103,450 — — 1,352,414 Land - acquisition & development 137,998 15,573 — — — 153,571 Total commercial loans 6,412,415 247,351 384,660 — — 7,044,426 Consumer loans Single-family residential 5,270,666 192 23,104 — — 5,293,962 Construction - custom 295,953 — — — — 295,953 Land - consumer lot loans 101,151 — 243 — — 101,394 HELOC 139,646 — 576 — — 140,222 Consumer 83,304 — 11 — — 83,315 Total consumer loans 5,890,720 192 23,934 — — 5,914,846 Total loans $ 12,303,135 $ 247,543 $ 408,594 $ — $ — $ 12,959,272 Total grade as a % of total gross loans 94.94 % 1.91 % 3.15 % — % — % The following tables provide information on amortized cost of loans receivable based on borrower payment activity. March 31, 2021 Performing Loans Non-Performing Loans Amount % of Total Amount % of Total (In thousands, except ratio data) Commercial loans Multi-family $ 1,987,120 100.0 % $ — — % Commercial real estate 2,201,839 99.6 9,226 0.4 Commercial & industrial 2,451,753 100.0 832 — Construction 923,594 99.8 1,423 0.2 Land - acquisition & development 147,971 98.4 2,340 1.6 Total commercial loans 7,712,277 99.8 13,821 0.2 Consumer loans Single-family residential 4,776,976 99.5 25,599 0.5 Construction - custom 308,831 100.0 — — Land - consumer lot loans 122,034 99.9 177 0.1 HELOC 144,760 99.8 306 0.2 Consumer 103,242 99.9 52 0.1 Total consumer loans 5,455,843 99.5 26,134 0.5 Total loans $ 13,168,120 99.7 % $ 39,955 0.3 % September 30, 2020 Performing Loans Non-Performing Loans Amount % of Total Amount % of Total (In thousands, except ratio data) Commercial loans Multi-family $ 1,538,240 100.0 % $ — — % Commercial real estate 1,880,917 99.8 3,771 0.2 Commercial & industrial 2,115,184 100.0 329 — Construction 1,350,745 99.9 1,669 0.1 Land - acquisition & development 153,571 100.0 — — Total commercial loans 7,038,657 99.9 5,769 0.1 Consumer loans Single-family residential 5,271,531 99.6 22,431 0.4 Construction - custom 295,953 100.0 — — Land - consumer lot loans 101,151 99.8 243 0.2 HELOC 139,669 99.6 553 0.4 Consumer 83,255 99.9 60 0.1 Total consumer loans 5,891,559 99.6 23,287 0.4 Total loans $ 12,930,216 99.8 % $ 29,056 0.2 %

Allowance for Losses on Loans (

Allowance for Losses on Loans (Tables)	6 Months Ended
	Mar. 31, 2021
Receivables [Abstract]
Allowance for Credit Losses by Loan Portfolio Segment and Class	The following tables summarize the activity in the allowance for loan losses by loan portfolio segment and class. Three Months Ended March 31, 2021 Beginning Allowance Charge-offs Recoveries Provision & Ending Allowance (In thousands) Commercial loans Multi-family $ 14,363 $ — $ — $ 3,413 $ 17,776 Commercial real estate 23,496 — 1,457 1,869 26,822 Commercial & industrial 44,317 (18) 11 3,484 47,794 Construction 26,365 — — (3,816) 22,549 Land - acquisition & development 10,666 — 410 (573) 10,503 Total commercial loans 119,207 (18) 1,878 4,377 125,444 Consumer loans Single-family residential 38,613 (106) 497 (3,896) 35,108 Construction - custom 3,594 — — (346) 3,248 Land - consumer lot loans 2,958 — 7 327 3,292 HELOC 2,362 — — (136) 2,226 Consumer 3,455 (84) 290 (326) 3,335 Total consumer loans 50,982 (190) 794 (4,377) 47,209 Total loans $ 170,189 $ (208) $ 2,672 $ — $ 172,653 Three Months Ended March 31, 2020 Beginning Allowance Charge-offs Recoveries Provision & Transfers (1) Ending Allowance (In thousands) Commercial loans Multi-family $ 10,506 $ — $ — $ 1,236 $ 11,742 Commercial real estate 13,067 (13) 1,020 565 14,639 Commercial & industrial 33,676 (129) 57 4,972 38,576 Construction 21,919 — 5 1,424 23,348 Land - acquisition & development 10,413 — 126 (140) 10,399 Total commercial loans 89,581 (142) 1,208 8,057 98,704 Consumer loans Single-family residential 46,356 — 192 268 46,816 Construction - custom 2,930 — — 245 3,175 Land - consumer lot loans 2,567 (77) 476 (388) 2,578 HELOC 2,034 — 1 211 2,246 Consumer 4,045 (230) 360 (593) 3,582 Total consumer loans 57,932 (307) 1,029 (257) 58,397 Total loans $ 147,513 $ (449) $ 2,237 $ 7,800 $ 157,101 (1) Provision & transfer amounts within the table do not include the provision for unfunded commitments of $400,000 Six Months Ended March 31, 2021 Beginning Allowance Charge-offs Recoveries Provision & Transfers (1) Ending Allowance (In thousands) Commercial loans Multi-family $ 13,853 $ — $ — $ 3,923 $ 17,776 Commercial real estate 22,516 — 2,246 2,060 26,822 Commercial & industrial 38,665 (20) 61 9,088 47,794 Construction 24,156 — — (1,607) 22,549 Land - acquisition & development 10,733 — 445 (675) 10,503 Total commercial loans 109,923 (20) 2,752 12,789 125,444 Consumer loans Single-family residential 45,186 (106) 1,276 (11,248) 35,108 Construction - custom 3,555 — — (307) 3,248 Land - consumer lot loans 2,729 — 14 549 3,292 HELOC 2,571 — — (345) 2,226 Consumer 2,991 (234) 516 62 3,335 Total consumer loans 57,032 (340) 1,806 (11,289) 47,209 Total loans $ 166,955 $ (360) $ 4,558 $ 1,500 $ 172,653 (1) Provision & transfer amounts within the table do not include the provision for unfunded commitments of $1,500,000 Six Months Ended March 31, 2020 Beginning Allowance Charge-offs Recoveries Provision & Transfers (1) Ending Allowance (In thousands) Commercial loans Multi-family $ 10,404 $ — $ 498 $ 840 $ 11,742 Commercial real estate 13,024 (111) 1,388 338 14,639 Commercial & industrial 32,235 (179) 201 6,319 38,576 Construction 22,768 — 59 521 23,348 Land - acquisition & development 10,904 (11) 1,586 (2,080) 10,399 Total commercial loans 89,335 (301) 3,732 5,938 98,704 Consumer loans Single-family residential 47,771 (15) 453 (1,393) 46,816 Construction - custom 2,880 — — 295 3,175 Land - consumer lot loans 2,635 (147) 486 (396) 2,578 HELOC 2,048 — 94 104 2,246 Consumer 4,615 (604) 669 (1,098) 3,582 Total consumer loans 59,949 (766) 1,702 (2,488) 58,397 Total loans $ 149,284 $ (1,067) $ 5,434 $ 3,450 $ 157,101 (1) Provision & transfer amounts within the table do not include the provision for unfunded commitments of $1,000,000
Summary of Loans Based on Credit Quality Indicators	The following tables present by primary credit quality indicator, loan class, and year of origination, the amortized cost basis of loans receivable as of March 31, 2021. Term Loans Amortized Cost Basis by Origination Year YTD 2021 2020 2019 2018 2017 Prior to 2017 Revolving Loans Revolving to Term Loans Total Loans Commercial loans Multi-family Pass $ 267,297 $ 507,301 $ 248,237 $ 295,532 $ 247,043 $ 344,441 $ 8,221 $ — $ 1,918,072 Special Mention — 1,769 — 4,039 2,844 1,934 — — 10,586 Substandard — — 7,546 651 3,746 46,519 — — 58,462 Total $ 267,297 $ 509,070 $ 255,783 $ 300,222 $ 253,633 $ 392,894 $ 8,221 $ — $ 1,987,120 Commercial real estate Pass $ 252,949 $ 443,877 $ 282,617 $ 274,651 $ 240,058 $ 440,678 $ 2,203 $ — $ 1,937,033 Special Mention — 194 4,432 33,380 1,697 23,144 — — 62,847 Substandard — 9,012 69,855 22,619 47,503 62,196 — — 211,185 Total $ 252,949 $ 453,083 $ 356,904 $ 330,650 $ 289,258 $ 526,018 $ 2,203 $ — $ 2,211,065 Commercial & industrial Pass $ 547,764 $ 631,137 $ 57,479 $ 52,576 $ 78,044 $ 159,841 $ 635,066 $ 11,944 $ 2,173,851 Special Mention — 9,798 6,785 630 18 — 31,636 — 48,867 Substandard 12,363 48,216 4,126 6,443 94 48,126 110,227 272 229,867 Total $ 560,127 $ 689,151 $ 68,390 $ 59,649 $ 78,156 $ 207,967 $ 776,929 $ 12,216 $ 2,452,585 Construction Pass $ 136,932 $ 311,836 $ 270,277 $ 67,312 $ — $ — $ 94,845 $ — $ 881,202 Substandard — 4,321 2,348 — 37,146 — — — 43,815 Total $ 136,932 $ 316,157 $ 272,625 $ 67,312 $ 37,146 $ — $ 94,845 $ — $ 925,017 Land - acquisition & development Pass $ 22,127 $ 39,505 $ 28,645 $ 18,007 $ 14,789 $ 4,011 $ 5,314 $ — $ 132,398 Special Mention — — — — — 15,573 — — 15,573 Substandard — — — — 2,340 — — — 2,340 Total $ 22,127 $ 39,505 $ 28,645 $ 18,007 $ 17,129 $ 19,584 $ 5,314 $ — $ 150,311 Total commercial loans Pass $ 1,227,069 $ 1,933,656 $ 887,255 $ 708,078 $ 579,934 $ 948,971 $ 745,649 $ 11,944 $ 7,042,556 Special Mention — 11,761 11,217 38,049 4,559 40,651 31,636 — 137,873 Substandard 12,363 61,549 83,875 29,713 90,829 156,841 110,227 272 545,669 Total $ 1,239,432 $ 2,006,966 $ 982,347 $ 775,840 $ 675,322 $ 1,146,463 $ 887,512 $ 12,216 $ 7,726,098 Term Loans Amortized Cost Basis by Origination Year YTD 2021 2020 2019 2018 2017 Prior to 2017 Revolving Loans Revolving to Term Loans Total Loans Consumer loans Single-family residential Current $ 499,799 $ 825,204 $ 512,811 $ 458,566 $ 514,115 $ 1,965,872 $ — $ — $ 4,776,367 30 days past due — — — 115 — 5,753 — — 5,868 60 days past due — — — — — 960 — — 960 90+ days past due — — — 466 169 18,745 — — 19,380 Total $ 499,799 $ 825,204 $ 512,811 $ 459,147 $ 514,284 $ 1,991,330 $ — $ — $ 4,802,575 Construction - custom Current $ 50,146 $ 242,667 $ 14,955 $ 1,063 $ — $ — $ — $ — $ 308,831 Total $ 50,146 $ 242,667 $ 14,955 $ 1,063 $ — $ — $ — $ — $ 308,831 Land - consumer lot loans Current $ 41,526 $ 35,849 $ 13,856 $ 5,304 $ 6,565 $ 18,758 $ — $ — $ 121,858 30 days past due — — — — — 93 — — 93 60 days past due — — — 185 — — — — 185 90+ days past due — — — — — 75 — — 75 Total $ 41,526 $ 35,849 $ 13,856 $ 5,489 $ 6,565 $ 18,926 $ — $ — $ 122,211 HELOC Current $ — $ — $ — $ — $ — $ 5,917 $ 137,531 $ 1,219 $ 144,667 30 days past due — — — — — 93 25 — 118 90+ days past due — — — — — 30 251 — 281 Total $ — $ — $ — $ — $ — $ 6,040 $ 137,807 $ 1,219 $ 145,066 Consumer Current $ 10,891 $ 8,245 $ 1,011 $ 45,983 $ — $ 14,000 $ 22,849 $ — $ 102,979 30 days past due — — 5 — 75 94 — — 174 60 days past due — — 2 — — — — — 2 90+ days past due — — 37 — 96 6 — — 139 Total $ 10,891 $ 8,245 $ 1,055 $ 45,983 $ 171 $ 14,100 $ 22,849 $ — $ 103,294 Total consumer loans Current $ 602,362 $ 1,111,965 $ 542,633 $ 510,916 $ 520,680 $ 2,004,547 $ 160,380 $ 1,219 $ 5,454,702 30 days past due — — 5 115 75 6,033 25 — 6,253 60 days past due — — 2 185 — 960 — — 1,147 90+ days past due — — 37 466 265 18,856 251 — 19,875 Total $ 602,362 $ 1,111,965 $ 542,677 $ 511,682 $ 521,020 $ 2,030,396 $ 160,656 $ 1,219 $ 5,481,977 The following tables provide the amortized cost of loans receivable based on risk rating categories as previously defined. March 31, 2021 Internally Assigned Grade Pass Special mention Substandard Doubtful Loss Total (In thousands, except ratio data) Loan type Commercial loans Multi-family $ 1,918,072 $ 10,586 $ 58,462 $ — $ — $ 1,987,120 Commercial real estate 1,937,033 62,847 211,185 — — 2,211,065 Commercial & industrial 2,173,851 48,867 229,867 — — 2,452,585 Construction 881,202 — 43,815 — — 925,017 Land - acquisition & development 132,398 15,573 2,340 — — 150,311 Total commercial loans 7,042,556 137,873 545,669 — — 7,726,098 Consumer loans Single-family residential 4,773,261 189 29,125 — — 4,802,575 Construction - custom 308,831 — — — — 308,831 Land - consumer lot loans 122,034 — 177 — — 122,211 HELOC 143,167 — 1,899 — — 145,066 Consumer 103,274 — 20 — — 103,294 Total consumer loans 5,450,567 189 31,221 — — 5,481,977 Total $ 12,493,123 $ 138,062 $ 576,890 $ — $ — $ 13,208,075 Total grade as a % of total loans 94.59 % 1.05 % 4.37 % — % — % September 30, 2020 Internally Assigned Grade Pass Special mention Substandard Doubtful Loss Total Gross Loans (In thousands, except ratio data) Loan type Commercial loans Multi-family $ 1,506,692 $ 13,721 $ 17,827 $ — $ — $ 1,538,240 Commercial real estate 1,681,230 92,184 111,274 — — 1,884,688 Commercial & industrial 1,898,709 64,695 152,109 — — 2,115,513 Construction 1,187,786 61,178 103,450 — — 1,352,414 Land - acquisition & development 137,998 15,573 — — — 153,571 Total commercial loans 6,412,415 247,351 384,660 — — 7,044,426 Consumer loans Single-family residential 5,270,666 192 23,104 — — 5,293,962 Construction - custom 295,953 — — — — 295,953 Land - consumer lot loans 101,151 — 243 — — 101,394 HELOC 139,646 — 576 — — 140,222 Consumer 83,304 — 11 — — 83,315 Total consumer loans 5,890,720 192 23,934 — — 5,914,846 Total loans $ 12,303,135 $ 247,543 $ 408,594 $ — $ — $ 12,959,272 Total grade as a % of total gross loans 94.94 % 1.91 % 3.15 % — % — % The following tables provide information on amortized cost of loans receivable based on borrower payment activity. March 31, 2021 Performing Loans Non-Performing Loans Amount % of Total Amount % of Total (In thousands, except ratio data) Commercial loans Multi-family $ 1,987,120 100.0 % $ — — % Commercial real estate 2,201,839 99.6 9,226 0.4 Commercial & industrial 2,451,753 100.0 832 — Construction 923,594 99.8 1,423 0.2 Land - acquisition & development 147,971 98.4 2,340 1.6 Total commercial loans 7,712,277 99.8 13,821 0.2 Consumer loans Single-family residential 4,776,976 99.5 25,599 0.5 Construction - custom 308,831 100.0 — — Land - consumer lot loans 122,034 99.9 177 0.1 HELOC 144,760 99.8 306 0.2 Consumer 103,242 99.9 52 0.1 Total consumer loans 5,455,843 99.5 26,134 0.5 Total loans $ 13,168,120 99.7 % $ 39,955 0.3 % September 30, 2020 Performing Loans Non-Performing Loans Amount % of Total Amount % of Total (In thousands, except ratio data) Commercial loans Multi-family $ 1,538,240 100.0 % $ — — % Commercial real estate 1,880,917 99.8 3,771 0.2 Commercial & industrial 2,115,184 100.0 329 — Construction 1,350,745 99.9 1,669 0.1 Land - acquisition & development 153,571 100.0 — — Total commercial loans 7,038,657 99.9 5,769 0.1 Consumer loans Single-family residential 5,271,531 99.6 22,431 0.4 Construction - custom 295,953 100.0 — — Land - consumer lot loans 101,151 99.8 243 0.2 HELOC 139,669 99.6 553 0.4 Consumer 83,255 99.9 60 0.1 Total consumer loans 5,891,559 99.6 23,287 0.4 Total loans $ 12,930,216 99.8 % $ 29,056 0.2 %

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value of Assets Measured on Recurring Basis	The following tables present the balance and level in the fair value hierarchy of assets and liabilities that are measured at fair value on a recurring basis. March 31, 2021 Level 1 Level 2 Level 3 Total (In thousands) Financial Assets Available-for-sale securities: U.S. government and agency securities $ — $ 71,512 $ — $ 71,512 Asset-backed securities — 1,183,977 — 1,183,977 Municipal bonds — 38,669 — 38,669 Corporate debt securities — 380,115 — 380,115 Mortgage-backed securities Agency pass-through certificates — 764,629 — 764,629 Total available-for-sale securities — 2,438,902 — 2,438,902 Client swap program hedges — 5,104 — 5,104 Mortgage loan fair value hedges — 2,135 — 2,135 Borrowings cash flow hedges — 59,198 — 59,198 Total financial assets $ — $ 2,505,339 $ — $ 2,505,339 Financial Liabilities Client swap program hedges $ — $ 5,104 $ — $ 5,104 Commercial loan fair value hedges — 4,610 — 4,610 Total financial liabilities $ — $ 9,714 $ — $ 9,714 September 30, 2020 Level 1 Level 2 Level 3 Total (In thousands) Financial Assets Available-for-sale securities: U.S. government and agency securities $ — $ 18,824 $ — $ 18,824 Asset-backed securities — 936,917 936,917 Municipal bonds — 38,315 — 38,315 Corporate debt securities — 287,184 — 287,184 Mortgage-backed securities Agency pass-through certificates — 968,252 — 968,252 Total available-for-sale securities — 2,249,492 — 2,249,492 Client swap program hedges — 48,201 — 48,201 Total financial assets $ — $ 2,297,693 $ — $ 2,297,693 Financial Liabilities Client swap program hedges $ — $ 48,201 $ — $ 48,201 Commercial loan fair value hedges — 8,492 — 8,492 Mortgage loan fair value hedges 16,061 16,061 Borrowings cash flow hedges — 17,375 — 17,375 Total financial liabilities $ — $ 90,129 $ — $ 90,129
Fair Value of Assets Measured on Nonrecurring Basis	The following tables present the aggregated balance of assets that were measured at fair value on a nonrecurring basis at March 31, 2021 and March 31, 2020, and the total gains (losses) resulting from those fair value adjustments during the respective periods. The estimated fair value measurements are shown gross of estimated selling costs. March 31, 2021 Three Months Ended March 31, 2021 Six Months Ended March 31, 2021 Level 1 Level 2 Level 3 Total Total Gains (Losses) (In thousands) (In thousands) Loans (1) $ — $ — $ — $ — $ (25) $ (69) Real estate owned (2) — — 722 722 148 101 Balance at end of period $ — $ — $ 722 $ 722 $ 123 $ 32 (1) The gains (losses) represent re-measurements of collateral-dependent loans. (2) The gains (losses) represent aggregate write-downs and charge-offs on real estate owned. March 31, 2020 Three Months Ended March 31, 2020 Six Months Ended March 31, 2020 Level 1 Level 2 Level 3 Total Total Gains (Losses) (In thousands) (In thousands) Loans (1) $ — $ — $ 810 $ 810 $ (246) $ (545) Real estate owned (2) — — 1,675 1,675 145 143 Balance at end of period $ — $ — $ 2,485 $ 2,485 $ (101) $ (402) (1) The gains (losses) represent re-measurements of collateral-dependent loans. (2) The gains (losses) represent aggregate write-downs and charge-offs on real estate owned.
Fair Value of Financial Instruments by Balance Sheet Grouping	Although management is not aware of any factors that would materially affect the estimated fair value amounts presented below, such amounts have not been comprehensively revalued for purposes of these financial statements since the dates shown, and therefore, estimates of fair value subsequent to those dates may differ significantly from the amounts presented below. March 31, 2021 September 30, 2020 Level in Fair Value Hierarchy Carrying Estimated Carrying Estimated ($ in thousands) Financial assets Cash and cash equivalents 1 $ 2,318,447 $ 2,318,447 $ 1,702,977 $ 1,702,977 Available-for-sale securities U.S. government and agency securities 2 71,512 71,512 18,824 18,824 Asset-backed securities 2 1,183,977 1,183,977 936,917 936,917 Municipal bonds 2 38,669 38,669 38,315 38,315 Corporate debt securities 2 380,115 380,115 287,184 287,184 Mortgage-backed securities Agency pass-through certificates 2 764,629 764,629 968,252 968,252 Total available-for-sale securities 2,438,902 2,438,902 2,249,492 2,249,492 Held-to-maturity securities Mortgage-backed securities Agency pass-through certificates 2 489,915 503,723 698,934 720,516 Commercial MBS 2 4,174 4,174 6,904 6,852 Total held-to-maturity securities 494,089 507,897 705,838 727,368 Loans receivable 3 13,035,423 13,419,101 12,792,317 13,392,089 FHLB and FRB stock 2 119,991 119,991 141,990 141,990 Other assets - client swap program hedges 2 5,104 5,104 48,201 48,201 Other assets - commercial fair value loan hedges 2 — — — — Other assets - mortgage loan fair value hedges 2 2,135 2,135 — — Other assets - borrowings cash flow hedges 2 59,198 59,198 — — Financial liabilities Time deposits 2 3,590,755 3,543,588 3,973,192 3,963,203 FHLB advances 2 2,150,000 2,115,171 2,700,000 2,722,509 Other liabilities - client swap program hedges 2 5,104 5,104 48,201 48,201 Other liabilities - commercial loan fair value hedges 2 4,610 4,610 8,492 8,492 Other liabilities - mortgage loan fair value hedges 2 — — 16,061 16,061 Other liabilities - borrowings cash flow hedges 2 — — 17,375 17,375
Reconciliation of Amortized Cost to Fair Value of Available-for-Sale and Held-to-Maturity Securities	The following tables provide details about the amortized cost and fair value of available-for-sale and held-to-maturity securities. March 31, 2021 Amortized Gross Unrealized Fair Yield Gains Losses ($ in thousands) Available-for-sale securities U.S. government and agency securities due 1 to 5 years $ 54,992 $ 516 $ — $ 55,508 0.50 % 5 to 10 years 15,897 107 — 16,004 2.05 Asset-backed securities 5 to 10 years 102,141 447 (718) 101,870 0.68 Over 10 years 1,071,530 10,994 (417) 1,082,107 1.07 Corporate debt securities due Within 1 year 31,742 126 (28) 31,840 1.98 1 to 5 years 195,442 7,120 — 202,562 1.67 5 to 10 years 65,888 751 (710) 65,929 3.14 Over 10 years 80,560 — (776) 79,784 3.44 Municipal bonds due 1 to 5 years 1,477 28 — 1,505 — 5 to 10 years 5,797 275 — 6,072 0.27 Over 10 years 29,929 1,163 — 31,092 5.85 Mortgage-backed securities Agency pass-through certificates 737,281 29,622 (2,274) 764,629 2.67 2,392,676 51,149 (4,923) 2,438,902 1.80 Held-to-maturity securities Mortgage-backed securities Agency pass-through certificates 489,915 13,808 — 503,723 3.16 Commercial MBS 4,174 — — 4,174 0.98 494,089 13,808 — 507,897 3.14 $ 2,886,765 $ 64,957 $ (4,923) $ 2,946,799 2.02 % September 30, 2020 Amortized Gross Unrealized Fair Yield Gains Losses ($ in thousands) Available-for-sale securities U.S. government and agency securities due 5 to 10 years $ 18,448 $ 376 $ — $ 18,824 2.05 % Asset-backed securities 5 to 10 years 38,289 — (1,600) 36,689 0.83 Over 10 years 906,489 647 (6,908) 900,228 1.14 Corporate debt securities due Within 1 year 54,209 337 (51) 54,495 1.22 1 to 5 years 128,289 3,366 (428) 131,227 1.78 5 to 10 years 97,157 4,305 — 101,462 1.50 Municipal bonds due 1 to 5 years 1,461 36 — 1,497 — Over 10 years 36,044 774 — 36,818 5.40 Mortgage-backed securities Agency pass-through certificates 929,713 39,166 (627) 968,252 2.82 2,210,099 49,007 (9,614) 2,249,492 1.97 Held-to-maturity securities Mortgage-backed securities Agency pass-through certificates 698,934 21,582 — 720,516 3.16 Commercial MBS 6,904 — (52) 6,852 1.02 705,838 21,582 (52) 727,368 3.14 $ 2,915,937 $ 70,589 $ (9,666) $ 2,976,860 2.25 %
Schedule of Unrealized Losses and Fair Value of Securities	The following tables show the gross unrealized losses and fair value of securities as of March 31, 2021 and September 30, 2020, by length of time that individual securities in each category have been in a continuous loss position. There were 38 and 51 securities with an unrealized loss as of March 31, 2021 and September 30, 2020, respectively. The decline in fair value since purchase is attributable to changes in interest rates. Because the Company does not intend to sell these securities and does not consider it more likely than not that it will be required to sell these securities before the recovery of amortized cost basis, which may be upon maturity, the Company does not consider these investments to have any credit impairment. March 31, 2021 Less than 12 months 12 months or more Total Unrealized Fair Unrealized Fair Unrealized Fair (In thousands) Available-for-sale securities Corporate debt securities $ (1,514) $ 125,191 $ — $ — $ (1,514) $ 125,191 Asset-backed securities (77) 80,046 (1,058) 125,681 (1,135) 205,727 Mortgage-backed securities (1,963) 55,679 (311) 31,951 (2,274) 87,630 (3,554) 260,916 (1,369) 157,632 (4,923) 418,548 Held-to-maturity securities Mortgage-backed securities — — — — — — $ (3,554) $ 260,916 $ (1,369) $ 157,632 $ (4,923) $ 418,548 September 30, 2020 Less than 12 months 12 months or more Total Unrealized Fair Unrealized Fair Unrealized Fair (In thousands) Available-for-sale securities Corporate debt securities $ (74) $ 45,875 $ (405) $ 24,596 $ (479) $ 70,471 Asset-backed securities (5,481) 587,746 (3,027) 204,369 (8,508) 792,115 Mortgage-backed securities (278) 41,897 (349) 56,196 (627) 98,093 (5,833) 675,518 (3,781) 285,161 (9,614) 960,679 Held-to-maturity securities Mortgage-backed securities (52) 6,853 — — (52) 6,853 $ (5,885) $ 682,371 $ (3,781) $ 285,161 $ (9,666) $ 967,532

Derivatives and Hedging Activ_2

Derivatives and Hedging Activities (Tables)	6 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Fair Value, Notional Amount and Balance Sheet Classification	The following tables present the fair value, notional amount and balance sheet classification of derivative assets and liabilities at March 31, 2021 and September 30, 2020. March 31, 2021 Derivative Assets Derivative Liabilities Interest rate contract purpose Balance Sheet Location Notional Fair Value Balance Sheet Location Notional Fair Value (In thousands) (In thousands) Client swap program hedges Other assets $ 653,904 $ 5,104 Other liabilities $ 653,904 $ 5,104 Commercial loan fair value hedges Other assets — — Other liabilities 90,918 4,610 Mortgage loan fair value hedges Other assets 500,000 2,135 Other liabilities — — Borrowings cash flow hedges Other assets 1,200,000 59,198 Other liabilities — — $ 2,353,904 $ 66,437 $ 744,822 $ 9,714 September 30, 2020 Derivative Assets Derivative Liabilities Interest rate contract purpose Balance Sheet Location Notional Fair Value Balance Sheet Location Notional Fair Value (In thousands) (In thousands) Client swap program hedges Other assets $ 656,074 $ 48,201 Other liabilities $ 656,074 $ 48,201 Commercial loan fair value hedges Other assets — — Other liabilities 93,316 8,492 Mortgage loan fair value hedges Other assets — — Other liabilities 500,000 16,061 Borrowings cash flow hedges Other assets — — Other liabilities 1,600,000 17,375 $ 656,074 $ 48,201 $ 2,849,390 $ 90,129
Schedule of Fair Value Hedge Accounting on Carrying Value of Hedged Items	The following tables present the impact of fair value hedge accounting on the carrying value of the hedged items at March 31, 2021 and September 30, 2020. (In thousands) March 31, 2021 Balance sheet line item in which hedged item is recorded Carrying value of hedged items Cumulative gain (loss) fair value hedge adjustment included in carrying amount of hedged items Loans receivable (1) (2) $ 1,934,688 $ 2,831 $ 1,934,688 $ 2,831 (1) Includes the amortized cost basis of the closed mortgage loan portfolios used to designate the hedging relationships in which the hedged items are the last layer expected to be remaining at the end of the hedging relationships. At March 31, 2021, the amortized cost basis of the closed loan portfolios used in the hedging relationships was $1,839,169,000, the cumulative basis adjustment associated with the hedging relationships was $(1,929,000), and the amount of the designated hedged items was $500,000,000. (2) Includes the amortized cost basis of commercial loans designated in fair value hedging relationships. At March 31, 2021, the amortized cost basis of the hedged commercial loans was $95,519,000 and the cumulative basis adjustment associated with the hedging relationships was $4,760,000. (In thousands) September 30, 2020 Balance sheet line item in which hedged item is recorded Carrying value of hedged items Cumulative gain (loss) fair value hedge adjustment included in carrying amount of hedged items Loans receivable (1) (2) $ 2,562,765 $ 24,664 $ 2,562,765 $ 24,664 (1) Includes the amortized cost basis of the closed mortgage loan portfolios used to designate the hedging relationships in which the hedged items are the last layer expected to be remaining at the end of the hedging relationships. At September 30, 2020, the amortized cost basis of the closed loan portfolios used in the hedging relationships was $2,461,008,000, the cumulative basis adjustment associated with the hedging relationships was $16,049,000, and the amount of the designated hedged items was $500,000,000. (2) Includes the amortized cost basis of commercial loans designated in fair value hedging relationships. At September 30, 2020, the amortized cost basis of the hedged commercial loans was $101,757,000 and the cumulative basis adjustment associated with the hedging relationships was $8,615,000.
Schedule of Impact of Derivative Instruments	The following tables present the gain (loss) recognized in AOCI on derivative instruments related to cash flow hedges on borrowings for the periods presented, as well as the effect of reclassification adjustments. (In thousands) Three Months Ended March 31, Amounts recognized in AOCI 2021 2020 Interest rate contracts: Pay fixed/receive floating swaps on borrowings cash flow hedges $ 70,565 $ (12,428) Reclassification adjustment of net (gain)/loss included in net income (14,110) — Total pre-tax gain/(loss) recognized in AOCI $ 56,455 $ (12,428) (In thousands) Six Months Ended March 31, Amounts recognized in AOCI 2021 2020 Interest rate contracts: Pay fixed/receive floating swaps on borrowings cash flow hedges $ 90,683 $ (9,313) Reclassification adjustment of net (gain)/loss included in net income (14,110) — Total pre-tax gain/(loss) recognized in AOCI $ 76,573 $ (9,313) The following tables present the impact of derivative instruments (client swap program) that are not designated in accounting hedges under ASC 815 for the periods presented. (In thousands) Three Months Ended March 31, Derivative instruments Classification of gain/(loss) recognized in income on derivative instrument 2021 2020 Interest rate contracts: Pay fixed/receive floating swap Other noninterest income $ 40,929 $ (28,184) Receive fixed/pay floating swap Other noninterest income (40,929) 28,184 $ — $ — (In thousands) Six Months Ended March 31, Derivative instruments Classification of gain/(loss) recognized in income on derivative instrument 2021 2020 Interest rate contracts: Pay fixed/receive floating swap Other noninterest income $ 53,305 $ (22,776) Receive fixed/pay floating swap Other noninterest income (53,305) 22,776 $ — $ —
Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position, Location	The following tables present the gain (loss) on derivative instruments in fair value and cash flow accounting hedging relationships under ASC 815 for the periods presented. Three Months Ended March 31, 2021 Three Months Ended March 31, 2020 Interest income on loans receivable Interest expense on FHLB advances Interest income on loans receivable Interest expense on FHLB advances (In thousands) (In thousands) Interest income/(expense), including the effects of fair value and cash flow hedges $ 132,757 $ (11,991) $ 138,549 $ (13,368) Gain/(loss) on fair value hedging relationships: Interest rate contracts Amounts related to interest settlements on derivatives $ (1,563) $ (112) Recognized on derivatives 17,491 (24,676) Recognized on hedged items (17,377) 24,666 Net income/(expense) recognized on fair value hedges $ (1,449) $ (122) Gain/(loss) on cash flow hedging relationships: Interest rate contracts Amounts related to interest settlements on derivatives $ 3,066 $ 498 Amount of derivative gain/(loss) reclassified from AOCI into interest income/expense 14,110 — Net income/(expense) recognized on cash flow hedges $ 17,176 $ 498 Six months ended March 31, 2021 Six months ended March 31, 2020 Interest income on loans receivable Interest expense on FHLB advances Interest income on loans receivable Interest expense on FHLB advances (In thousands) (In thousands) Interest income/(expense), including the effects of fair value and cash flow hedges $ 266,428 $ (25,189) $ 280,695 $ (27,026) Gain/(loss) on fair value hedging relationships: Interest rate contracts Amounts related to interest settlements on derivatives $ (3,104) $ (186) Recognized on derivatives 22,078 (19,984) Recognized on hedged items (21,833) 20,073 Net income/(expense) recognized on fair value hedges $ (2,859) $ (97) Gain/(loss) on cash flow hedging relationships: Interest rate contracts Amounts related to interest settlements on derivatives $ 6,664 $ 284 Amount of derivative gain/(loss) reclassified from AOCI into interest income/expense 14,110 — Net income/(expense) recognized on cash flow hedges $ 20,774 $ 284

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) $ / shares in Units, $ in Thousands	Feb. 08, 2021$ / sharesshares	Mar. 31, 2021USD ($)branch	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)
Accounting Policies [Line Items]
Number of bank branches | branch		232
Increase (decrease) to retained earnings for the cumulative effect of adopting ASC 326		$ 2,332,953	$ 1,964,612	$ 2,061,767	$ 2,014,133	$ 2,031,127	$ 2,032,995
Cash collateral		1,500			97,600
Loans in process		1,982,225			1,456,072
Proceeds from issuance of preferred stock, net		293,325	0
Dividend rate	4.875%
Public Offering
Accounting Policies [Line Items]
Number of depositary shares | shares	12,000,000
Percentage of preferred stock	2.50%
Public offering price (in usd per share) | $ / shares	$ 25
Public Offering | Series A Preferred Stock
Accounting Policies [Line Items]
Number of depositary shares | shares	300,000
Financing Receivable
Accounting Policies [Line Items]
Loans in process		3,348,654			2,738,095
Retained Earnings
Accounting Policies [Line Items]
Increase (decrease) to retained earnings for the cumulative effect of adopting ASC 326		$ 1,468,093	$ 1,384,833	$ 1,443,280	$ 1,420,906	$ 1,365,397	1,335,909
Cumulative Effect, Period of Adoption, Adjustment
Accounting Policies [Line Items]
Increase (decrease) to retained earnings for the cumulative effect of adopting ASC 326							(21,945)
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings
Accounting Policies [Line Items]
Increase (decrease) to retained earnings for the cumulative effect of adopting ASC 326							$ (21,945)

Dividends and Share Repurchas_2

Dividends and Share Repurchases (Details) - USD ($) $ / shares in Units, $ in Thousands	Apr. 27, 2021	Apr. 02, 2021	Feb. 19, 2021	Jan. 26, 2021	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Subsequent Event [Line Items]
Cash dividends per share (in dollars per share)			$ 0.23		$ 0.23	$ 0.22	$ 0.45	$ 0.43
Stock repurchased (in shares)					2,824,588
Average cost per share (in dollars per share)					$ 31.53
Total cost					$ 89,071	$ 78,610	$ 89,772	$ 112,089
Remaining shares authorized to be repurchased (in shares)					11,769,687		11,769,687
Additional shares authorized for repurchase (in shares)				10,000,000
Dutch Auction
Subsequent Event [Line Items]
Stock repurchased (in shares)					1,715,335
Total cost					$ 53,780
Subsequent Event
Subsequent Event [Line Items]
Common stock dividends declared (in dollars per share)	$ 0.23
Preferred stock dividends declared (in dollars per share)		$ 9.0729
Depository dividends declared (in dollars per share)		$ 0.22682250

Loans Receivable - Schedule of

Loans Receivable - Schedule of Loans Receivable (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 15,265,588,000		$ 14,467,722,000
Ratio of loan type to all loans	100.00%		100.00%
Allowance for credit losses on loans	$ 172,653,000	$ 170,189,000	$ 166,955,000	$ 157,101,000	$ 147,513,000	$ 149,284,000
Loans in process	1,982,225,000		1,456,072,000
Net deferred fees, costs and discounts	75,287,000		52,378,000
Total loan contra accounts	2,230,165,000		1,675,405,000
Net loans	13,035,423,000		12,792,317,000
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 9,387,560,000		$ 8,163,029,000
Ratio of loan type to all loans	61.50%		56.30%
Allowance for credit losses on loans	$ 125,444,000	119,207,000	$ 109,923,000	98,704,000	89,581,000	89,335,000
Commercial loans | Multi-family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 2,008,192,000		$ 1,538,762,000
Ratio of loan type to all loans	13.20%		10.60%
Allowance for credit losses on loans	$ 17,776,000	14,363,000	$ 13,853,000	11,742,000	10,506,000	10,404,000
Commercial loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 2,226,560,000		$ 1,895,086,000
Ratio of loan type to all loans	14.60%		13.10%
Allowance for credit losses on loans	$ 26,822,000	23,496,000	$ 22,516,000	14,639,000	13,067,000	13,024,000
Commercial loans | Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 2,471,823,000		$ 2,132,160,000
Ratio of loan type to all loans	16.20%		14.70%
Allowance for credit losses on loans	$ 47,794,000	44,317,000	$ 38,665,000	38,576,000	33,676,000	32,235,000
Commercial loans | Commercial & industrial | SBA Payroll Protection Program, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	711,405,000		762,004,000
Allowance for credit losses on loans	0		0
Net loans	695,752,000		745,081,000
Commercial loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 2,495,961,000		$ 2,403,276,000
Ratio of loan type to all loans	16.30%		16.60%
Allowance for credit losses on loans	$ 22,549,000	26,365,000	$ 24,156,000	23,348,000	21,919,000	22,768,000
Commercial loans | Land - acquisition & development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 185,024,000		$ 193,745,000
Ratio of loan type to all loans	1.20%		1.30%
Allowance for credit losses on loans	$ 10,503,000	10,666,000	$ 10,733,000	10,399,000	10,413,000	10,904,000
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 5,878,028,000		$ 6,304,693,000
Ratio of loan type to all loans	38.50%		43.70%
Allowance for credit losses on loans	$ 47,209,000	50,982,000	$ 57,032,000	58,397,000	57,932,000	59,949,000
Consumer loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 678,469,000		$ 674,879,000
Ratio of loan type to all loans	4.50%		4.70%
Allowance for credit losses on loans	$ 3,248,000	3,594,000	$ 3,555,000	3,175,000	2,930,000	2,880,000
Consumer loans | Single-family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 4,828,535,000		$ 5,304,689,000
Ratio of loan type to all loans	31.60%		36.70%
Allowance for credit losses on loans	$ 35,108,000	38,613,000	$ 45,186,000	46,816,000	46,356,000	47,771,000
Consumer loans | Land - consumer lot loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 123,351,000		$ 102,263,000
Ratio of loan type to all loans	0.80%		0.70%
Allowance for credit losses on loans	$ 3,292,000	2,958,000	$ 2,729,000	2,578,000	2,567,000	2,635,000
Consumer loans | HELOC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 144,528,000		$ 139,703,000
Ratio of loan type to all loans	0.90%		1.00%
Allowance for credit losses on loans	$ 2,226,000	2,362,000	$ 2,571,000	2,246,000	2,034,000	2,048,000
Consumer loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 103,145,000		$ 83,159,000
Ratio of loan type to all loans	0.70%		0.60%
Allowance for credit losses on loans	$ 3,335,000	$ 3,455,000	$ 2,991,000	$ 3,582,000	$ 4,045,000	$ 4,615,000

Loans Receivable - Additional I

Loans Receivable - Additional Information (Details) $ in Thousands	Mar. 31, 2021USD ($)loanbusiness	Mar. 31, 2021USD ($)business	Dec. 31, 2020USD ($)business	Sep. 30, 2020USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest receivable for loans	$ 48,676	$ 48,676		$ 48,704
Loans pledged to secure borrowings from the Federal Home Loan Bank	$ 6,314,864	6,314,864		$ 5,361,504
Nonaccrual interest income recognized		5,228
Impaired, interest income on accrual accrual and performed loans		$ 769
Number of businesses assisted, CARES Act | business	2,000,000	2,000,000	6,500
Basis point reduction, minimum		1.00%
Basis point reduction, maximum		2.00%
Percent of TDRs classified as performing	97.70%
Single family residential loans as percentage of restructured loans	92.60%	92.60%
Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term for payment and rate reduction		6 months
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term for payment and rate reduction		24 months
Performing Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring, amount	$ 78,282
SBA Payroll Protection Program, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount of PPP loans authorized, CARES Act		$ 235,000	$ 780,000
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans modified | loan	45
Total loans modified	$ 14,000	14,000
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans modified | loan	10
Total loans modified	$ 89,000	$ 89,000

Loans Receivable - Non-accrual

Loans Receivable - Non-accrual Loans and Loans 90 Days or More Past Due and Accruing (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual percent of total loans	0.30%	0.22%
Financial Asset Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 39,955	$ 29,056
Non-accrual loans with no related ACL	0	0
90 days or more past due and accruing	0	950
Financial Asset Originated | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	13,821	5,769
Non-accrual loans with no related ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated | Commercial loans | Multi-family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	0	0
Non-accrual loans with no related ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated | Commercial loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	9,226	3,771
Non-accrual loans with no related ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated | Commercial loans | Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	832	329
Non-accrual loans with no related ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated | Commercial loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,423	1,669
Non-accrual loans with no related ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated | Commercial loans | Land - acquisition & development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	2,340	0
Non-accrual loans with no related ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated | Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	26,134	23,287
Non-accrual loans with no related ACL	0	0
90 days or more past due and accruing	0	950
Financial Asset Originated | Consumer loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	0	0
Non-accrual loans with no related ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated | Consumer loans | Single-family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	25,599	22,431
Non-accrual loans with no related ACL	0	0
90 days or more past due and accruing	0	933
Financial Asset Originated | Consumer loans | Land - consumer lot loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	177	243
Non-accrual loans with no related ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated | Consumer loans | HELOC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	306	553
Non-accrual loans with no related ACL	0	0
90 days or more past due and accruing	0	0
Financial Asset Originated | Consumer loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	52	60
Non-accrual loans with no related ACL	0	0
90 days or more past due and accruing	$ 0	$ 17

Loans Receivable - Loan Delinqu

Loans Receivable - Loan Delinquencies by Loan Portfolio and Class (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable (amortized cost)	$ 13,208,075	$ 12,959,272
Days delinquent, current	13,169,902	12,928,463
Days delinquent, past due	$ 38,173	$ 30,809
% based on $, current	99.71%	99.76%
% based on $, past due	0.29%	0.24%
30 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 7,465	$ 4,470
% based on $, past due	0.06%	0.03%
60 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 1,733	$ 3,973
% based on $, past due	0.01%	0.03%
90 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 28,975	$ 22,366
% based on $, past due	0.22%	0.17%
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable (amortized cost)	$ 7,726,098	$ 7,044,426
Days delinquent, current	7,715,200	7,041,423
Days delinquent, past due	$ 10,898	$ 3,003
% based on $, past due	0.14%	0.04%
Commercial loans | 30 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 1,212	$ 0
Commercial loans | 60 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	586	778
Commercial loans | 90 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	9,100	2,225
Commercial loans | Multi-family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable (amortized cost)	1,987,120	1,538,240
Days delinquent, current	1,986,645	1,538,240
Days delinquent, past due	$ 475	$ 0
% based on $, past due	0.02%	0.00%
Commercial loans | Multi-family | 30 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 0	$ 0
Commercial loans | Multi-family | 60 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	475	0
Commercial loans | Multi-family | 90 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	0	0
Commercial loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable (amortized cost)	2,211,065	1,884,688
Days delinquent, current	2,206,097	1,884,210
Days delinquent, past due	$ 4,968	$ 478
% based on $, past due	0.22%	0.03%
Commercial loans | Commercial real estate | 30 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 37	$ 0
Commercial loans | Commercial real estate | 60 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	111	195
Commercial loans | Commercial real estate | 90 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	4,820	283
Commercial loans | Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable (amortized cost)	2,452,585	2,115,513
Days delinquent, current	2,450,623	2,114,650
Days delinquent, past due	$ 1,962	$ 863
% based on $, past due	0.08%	0.04%
Commercial loans | Commercial & industrial | 30 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 1,175	$ 0
Commercial loans | Commercial & industrial | 60 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	0	583
Commercial loans | Commercial & industrial | 90 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	787	280
Commercial loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable (amortized cost)	925,017	1,352,414
Days delinquent, current	923,864	1,350,752
Days delinquent, past due	$ 1,153	$ 1,662
% based on $, past due	0.12%	0.12%
Commercial loans | Construction | 30 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 0	$ 0
Commercial loans | Construction | 60 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	0	0
Commercial loans | Construction | 90 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	1,153	1,662
Commercial loans | Land - acquisition & development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable (amortized cost)	150,311	153,571
Days delinquent, current	147,971	153,571
Days delinquent, past due	$ 2,340	$ 0
% based on $, past due	1.56%	0.00%
Commercial loans | Land - acquisition & development | 30 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 0	$ 0
Commercial loans | Land - acquisition & development | 60 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	0	0
Commercial loans | Land - acquisition & development | 90 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	2,340	0
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable (amortized cost)	5,481,977	5,914,846
Days delinquent, current	5,454,702	5,887,040
Days delinquent, past due	$ 27,275	$ 27,806
% based on $, past due	0.50%	0.47%
Consumer loans | 30 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 6,253	$ 4,470
Consumer loans | 60 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	1,147	3,195
Consumer loans | 90 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	19,875	20,141
Consumer loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable (amortized cost)	308,831	295,953
Days delinquent, current	308,831	295,953
Days delinquent, past due	$ 0	$ 0
% based on $, past due	0.00%	0.00%
Consumer loans | Construction | 30 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 0	$ 0
Consumer loans | Construction | 60 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	0	0
Consumer loans | Construction | 90 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	0	0
Consumer loans | Single-family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable (amortized cost)	4,802,575	5,293,962
Days delinquent, current	4,776,367	5,267,608
Days delinquent, past due	$ 26,208	$ 26,354
% based on $, past due	0.55%	0.50%
Consumer loans | Single-family residential | 30 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 5,868	$ 3,922
Consumer loans | Single-family residential | 60 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	960	3,108
Consumer loans | Single-family residential | 90 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	19,380	19,324
Consumer loans | Land - consumer lot loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable (amortized cost)	122,211	101,394
Days delinquent, current	121,858	101,029
Days delinquent, past due	$ 353	$ 365
% based on $, past due	0.29%	0.36%
Consumer loans | Land - consumer lot loans | 30 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 93	$ 152
Consumer loans | Land - consumer lot loans | 60 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	185	0
Consumer loans | Land - consumer lot loans | 90 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	75	213
Consumer loans | HELOC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable (amortized cost)	145,066	140,222
Days delinquent, current	144,667	139,491
Days delinquent, past due	$ 399	$ 731
% based on $, past due	0.28%	0.52%
Consumer loans | HELOC | 30 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 118	$ 275
Consumer loans | HELOC | 60 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	0	76
Consumer loans | HELOC | 90 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	281	380
Consumer loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable (amortized cost)	103,294	83,315
Days delinquent, current	102,979	82,959
Days delinquent, past due	$ 315	$ 356
% based on $, past due	0.30%	0.43%
Consumer loans | Consumer | 30 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 174	$ 121
Consumer loans | Consumer | 60 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	2	11
Consumer loans | Consumer | 90 Days Delinquent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Days delinquent, past due	$ 139	$ 224

Loans Receivable - Loans Based

Loans Receivable - Loans Based on Credit Quality Indicators (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 13,208,075	$ 12,959,272
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	12,493,123	12,303,135
Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	138,062	247,543
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	576,890	408,594
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	1,239,432
2020	2,006,966
2019	982,347
2018	775,840
2017	675,322
Prior to 2017	1,146,463
Revolving Loans	887,512
Revolving to Term Loans	12,216
Total Loans	7,726,098	7,044,426
Commercial loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	1,227,069
2020	1,933,656
2019	887,255
2018	708,078
2017	579,934
Prior to 2017	948,971
Revolving Loans	745,649
Revolving to Term Loans	11,944
Total Loans	7,042,556	6,412,415
Commercial loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	11,761
2019	11,217
2018	38,049
2017	4,559
Prior to 2017	40,651
Revolving Loans	31,636
Revolving to Term Loans	0
Total Loans	137,873	247,351
Commercial loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	12,363
2020	61,549
2019	83,875
2018	29,713
2017	90,829
Prior to 2017	156,841
Revolving Loans	110,227
Revolving to Term Loans	272
Total Loans	545,669	384,660
Commercial loans | Multi-family
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	267,297
2020	509,070
2019	255,783
2018	300,222
2017	253,633
Prior to 2017	392,894
Revolving Loans	8,221
Revolving to Term Loans	0
Total Loans	1,987,120	1,538,240
Commercial loans | Multi-family | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	267,297
2020	507,301
2019	248,237
2018	295,532
2017	247,043
Prior to 2017	344,441
Revolving Loans	8,221
Revolving to Term Loans	0
Total Loans	1,918,072	1,506,692
Commercial loans | Multi-family | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	1,769
2019	0
2018	4,039
2017	2,844
Prior to 2017	1,934
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	10,586	13,721
Commercial loans | Multi-family | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	7,546
2018	651
2017	3,746
Prior to 2017	46,519
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	58,462	17,827
Commercial loans | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	252,949
2020	453,083
2019	356,904
2018	330,650
2017	289,258
Prior to 2017	526,018
Revolving Loans	2,203
Revolving to Term Loans	0
Total Loans	2,211,065	1,884,688
Commercial loans | Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	252,949
2020	443,877
2019	282,617
2018	274,651
2017	240,058
Prior to 2017	440,678
Revolving Loans	2,203
Revolving to Term Loans	0
Total Loans	1,937,033	1,681,230
Commercial loans | Commercial real estate | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	194
2019	4,432
2018	33,380
2017	1,697
Prior to 2017	23,144
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	62,847	92,184
Commercial loans | Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	9,012
2019	69,855
2018	22,619
2017	47,503
Prior to 2017	62,196
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	211,185	111,274
Commercial loans | Commercial & industrial
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	560,127
2020	689,151
2019	68,390
2018	59,649
2017	78,156
Prior to 2017	207,967
Revolving Loans	776,929
Revolving to Term Loans	12,216
Total Loans	2,452,585	2,115,513
Commercial loans | Commercial & industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	547,764
2020	631,137
2019	57,479
2018	52,576
2017	78,044
Prior to 2017	159,841
Revolving Loans	635,066
Revolving to Term Loans	11,944
Total Loans	2,173,851	1,898,709
Commercial loans | Commercial & industrial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	9,798
2019	6,785
2018	630
2017	18
Prior to 2017	0
Revolving Loans	31,636
Revolving to Term Loans	0
Total Loans	48,867	64,695
Commercial loans | Commercial & industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	12,363
2020	48,216
2019	4,126
2018	6,443
2017	94
Prior to 2017	48,126
Revolving Loans	110,227
Revolving to Term Loans	272
Total Loans	229,867	152,109
Commercial loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	136,932
2020	316,157
2019	272,625
2018	67,312
2017	37,146
Prior to 2017	0
Revolving Loans	94,845
Revolving to Term Loans	0
Total Loans	925,017	1,352,414
Commercial loans | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	136,932
2020	311,836
2019	270,277
2018	67,312
2017	0
Prior to 2017	0
Revolving Loans	94,845
Revolving to Term Loans	0
Total Loans	881,202	1,187,786
Commercial loans | Construction | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	0	61,178
Commercial loans | Construction | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	4,321
2019	2,348
2018	0
2017	37,146
Prior to 2017	0
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	43,815	103,450
Commercial loans | Land - acquisition & development
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	22,127
2020	39,505
2019	28,645
2018	18,007
2017	17,129
Prior to 2017	19,584
Revolving Loans	5,314
Revolving to Term Loans	0
Total Loans	150,311	153,571
Commercial loans | Land - acquisition & development | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	22,127
2020	39,505
2019	28,645
2018	18,007
2017	14,789
Prior to 2017	4,011
Revolving Loans	5,314
Revolving to Term Loans	0
Total Loans	132,398	137,998
Commercial loans | Land - acquisition & development | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	0
2018	0
2017	0
Prior to 2017	15,573
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	15,573	15,573
Commercial loans | Land - acquisition & development | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	0
2018	0
2017	2,340
Prior to 2017	0
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	2,340	0
Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	602,362
2020	1,111,965
2019	542,677
2018	511,682
2017	521,020
Prior to 2017	2,030,396
Revolving Loans	160,656
Revolving to Term Loans	1,219
Total Loans	5,481,977	5,914,846
Consumer loans | Current
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	602,362
2020	1,111,965
2019	542,633
2018	510,916
2017	520,680
Prior to 2017	2,004,547
Revolving Loans	160,380
Revolving to Term Loans	1,219
Total Loans	5,454,702
Consumer loans | 30 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	5
2018	115
2017	75
Prior to 2017	6,033
Revolving Loans	25
Revolving to Term Loans	0
Total Loans	6,253
Consumer loans | 60 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	2
2018	185
2017	0
Prior to 2017	960
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	1,147
Consumer loans | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	37
2018	466
2017	265
Prior to 2017	18,856
Revolving Loans	251
Revolving to Term Loans	0
Total Loans	19,875
Consumer loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	5,450,567	5,890,720
Consumer loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	189	192
Consumer loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	31,221	23,934
Consumer loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	50,146
2020	242,667
2019	14,955
2018	1,063
2017	0
Prior to 2017	0
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	308,831	295,953
Consumer loans | Construction | Current
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	50,146
2020	242,667
2019	14,955
2018	1,063
2017	0
Prior to 2017	0
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	308,831
Consumer loans | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	308,831	295,953
Consumer loans | Construction | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	0	0
Consumer loans | Construction | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	0	0
Consumer loans | Single-family residential
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	499,799
2020	825,204
2019	512,811
2018	459,147
2017	514,284
Prior to 2017	1,991,330
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	4,802,575	5,293,962
Consumer loans | Single-family residential | Current
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	499,799
2020	825,204
2019	512,811
2018	458,566
2017	514,115
Prior to 2017	1,965,872
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	4,776,367
Consumer loans | Single-family residential | 30 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	0
2018	115
2017	0
Prior to 2017	5,753
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	5,868
Consumer loans | Single-family residential | 60 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	0
2018	0
2017	0
Prior to 2017	960
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	960
Consumer loans | Single-family residential | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	0
2018	466
2017	169
Prior to 2017	18,745
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	19,380
Consumer loans | Single-family residential | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	4,773,261	5,270,666
Consumer loans | Single-family residential | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	189	192
Consumer loans | Single-family residential | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	29,125	23,104
Consumer loans | Land - consumer lot loans
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	41,526
2020	35,849
2019	13,856
2018	5,489
2017	6,565
Prior to 2017	18,926
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	122,211	101,394
Consumer loans | Land - consumer lot loans | Current
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	41,526
2020	35,849
2019	13,856
2018	5,304
2017	6,565
Prior to 2017	18,758
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	121,858
Consumer loans | Land - consumer lot loans | 30 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	0
2018	0
2017	0
Prior to 2017	93
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	93
Consumer loans | Land - consumer lot loans | 60 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	0
2018	185
2017	0
Prior to 2017	0
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	185
Consumer loans | Land - consumer lot loans | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	0
2018	0
2017	0
Prior to 2017	75
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	75
Consumer loans | Land - consumer lot loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	122,034	101,151
Consumer loans | Land - consumer lot loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	0	0
Consumer loans | Land - consumer lot loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	177	243
Consumer loans | HELOC
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	0
2018	0
2017	0
Prior to 2017	6,040
Revolving Loans	137,807
Revolving to Term Loans	1,219
Total Loans	145,066	140,222
Consumer loans | HELOC | Current
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	0
2018	0
2017	0
Prior to 2017	5,917
Revolving Loans	137,531
Revolving to Term Loans	1,219
Total Loans	144,667
Consumer loans | HELOC | 30 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	0
2018	0
2017	0
Prior to 2017	93
Revolving Loans	25
Revolving to Term Loans	0
Total Loans	118
Consumer loans | HELOC | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	0
2018	0
2017	0
Prior to 2017	30
Revolving Loans	251
Revolving to Term Loans	0
Total Loans	281
Consumer loans | HELOC | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	143,167	139,646
Consumer loans | HELOC | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	0	0
Consumer loans | HELOC | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	1,899	576
Consumer loans | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	10,891
2020	8,245
2019	1,055
2018	45,983
2017	171
Prior to 2017	14,100
Revolving Loans	22,849
Revolving to Term Loans	0
Total Loans	103,294	83,315
Consumer loans | Consumer | Current
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	10,891
2020	8,245
2019	1,011
2018	45,983
2017	0
Prior to 2017	14,000
Revolving Loans	22,849
Revolving to Term Loans	0
Total Loans	102,979
Consumer loans | Consumer | 30 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	5
2018	0
2017	75
Prior to 2017	94
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	174
Consumer loans | Consumer | 60 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	2
2018	0
2017	0
Prior to 2017	0
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	2
Consumer loans | Consumer | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
YTD 2021	0
2020	0
2019	37
2018	0
2017	96
Prior to 2017	6
Revolving Loans	0
Revolving to Term Loans	0
Total Loans	139
Consumer loans | Consumer | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	103,274	83,304
Consumer loans | Consumer | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	0	0
Consumer loans | Consumer | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 20	$ 11

Allowance for Losses on Loans -

Allowance for Losses on Loans - Activity in Allowance for Loan Losses by Loan Portfolio Segment and Class (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	$ 170,189	$ 147,513	$ 166,955	$ 149,284
Charge-offs	(208)	(449)	(360)	(1,067)
Recoveries	2,672	2,237	4,558	5,434
Provision & Transfers	0	7,800	1,500	3,450
Ending Allowance	172,653	157,101	172,653	157,101
Unfunded commitments
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision & Transfers		400	1,500	1,000
Commercial loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	119,207	89,581	109,923	89,335
Charge-offs	(18)	(142)	(20)	(301)
Recoveries	1,878	1,208	2,752	3,732
Provision & Transfers	4,377	8,057	12,789	5,938
Ending Allowance	125,444	98,704	125,444	98,704
Commercial loans | Multi-family
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	14,363	10,506	13,853	10,404
Charge-offs	0	0	0	0
Recoveries	0	0	0	498
Provision & Transfers	3,413	1,236	3,923	840
Ending Allowance	17,776	11,742	17,776	11,742
Commercial loans | Commercial real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	23,496	13,067	22,516	13,024
Charge-offs	0	(13)	0	(111)
Recoveries	1,457	1,020	2,246	1,388
Provision & Transfers	1,869	565	2,060	338
Ending Allowance	26,822	14,639	26,822	14,639
Commercial loans | Commercial & industrial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	44,317	33,676	38,665	32,235
Charge-offs	(18)	(129)	(20)	(179)
Recoveries	11	57	61	201
Provision & Transfers	3,484	4,972	9,088	6,319
Ending Allowance	47,794	38,576	47,794	38,576
Commercial loans | Construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	26,365	21,919	24,156	22,768
Charge-offs	0	0	0	0
Recoveries	0	5	0	59
Provision & Transfers	(3,816)	1,424	(1,607)	521
Ending Allowance	22,549	23,348	22,549	23,348
Commercial loans | Land - acquisition & development
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	10,666	10,413	10,733	10,904
Charge-offs	0	0	0	(11)
Recoveries	410	126	445	1,586
Provision & Transfers	(573)	(140)	(675)	(2,080)
Ending Allowance	10,503	10,399	10,503	10,399
Consumer loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	50,982	57,932	57,032	59,949
Charge-offs	(190)	(307)	(340)	(766)
Recoveries	794	1,029	1,806	1,702
Provision & Transfers	(4,377)	(257)	(11,289)	(2,488)
Ending Allowance	47,209	58,397	47,209	58,397
Consumer loans | Construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	3,594	2,930	3,555	2,880
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision & Transfers	(346)	245	(307)	295
Ending Allowance	3,248	3,175	3,248	3,175
Consumer loans | Single-family residential
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	38,613	46,356	45,186	47,771
Charge-offs	(106)	0	(106)	(15)
Recoveries	497	192	1,276	453
Provision & Transfers	(3,896)	268	(11,248)	(1,393)
Ending Allowance	35,108	46,816	35,108	46,816
Consumer loans | Land - consumer lot loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	2,958	2,567	2,729	2,635
Charge-offs	0	(77)	0	(147)
Recoveries	7	476	14	486
Provision & Transfers	327	(388)	549	(396)
Ending Allowance	3,292	2,578	3,292	2,578
Consumer loans | HELOC
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	2,362	2,034	2,571	2,048
Charge-offs	0	0	0	0
Recoveries	0	1	0	94
Provision & Transfers	(136)	211	(345)	104
Ending Allowance	2,226	2,246	2,226	2,246
Consumer loans | Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	3,455	4,045	2,991	4,615
Charge-offs	(84)	(230)	(234)	(604)
Recoveries	290	360	516	669
Provision & Transfers	(326)	(593)	62	(1,098)
Ending Allowance	$ 3,335	$ 3,582	$ 3,335	$ 3,582

Allowance for Losses on Loans_2

Allowance for Losses on Loans - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision (release) for credit losses	$ 0	$ 8,200,000	$ 3,000,000	$ 4,450,000
Net (charge-offs) recoveries	2,464,000	1,788,000	4,198,000	4,367,000
Allowance for credit losses on loans	172,653,000	157,101,000	172,653,000	157,101,000	$ 170,189,000	$ 166,955,000	$ 147,513,000	$ 149,284,000
Loans receivable, net of allowance for loan losses	13,035,423,000		13,035,423,000			12,792,317,000
Gross PPP loans	15,265,588,000		15,265,588,000			14,467,722,000
Gross loans	$ 13,208,075,000		$ 13,208,075,000			$ 12,959,272,000
% based on $, past due	0.29%		0.29%			0.24%
Financial Asset Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 39,955,000		$ 39,955,000			$ 29,056,000
Non-Performing Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 48,943,000		$ 48,943,000			$ 37,695,000
Ratio of non-performing assets to total assets	0.25%		0.25%			0.20%
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses on loans	$ 125,444,000	98,704,000	$ 125,444,000	98,704,000	119,207,000	$ 109,923,000	89,581,000	89,335,000
Gross PPP loans	9,387,560,000		9,387,560,000			8,163,029,000
Gross loans	$ 7,726,098,000		$ 7,726,098,000			$ 7,044,426,000
% based on $, past due	0.14%		0.14%			0.04%
Commercial loans | Financial Asset Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 13,821,000		$ 13,821,000			$ 5,769,000
Commercial loans | Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses on loans	47,794,000	$ 38,576,000	47,794,000	$ 38,576,000	$ 44,317,000	38,665,000	$ 33,676,000	$ 32,235,000
Gross PPP loans	2,471,823,000		2,471,823,000			2,132,160,000
Gross loans	$ 2,452,585,000		$ 2,452,585,000			$ 2,115,513,000
% based on $, past due	0.08%		0.08%			0.04%
Commercial loans | Commercial & industrial | Financial Asset Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 832,000		$ 832,000			$ 329,000
Commercial loans | Commercial & industrial | SBA Payroll Protection Program, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses on loans	0		0			0
Loans receivable, net of allowance for loan losses	695,752,000		695,752,000			745,081,000
Gross PPP loans	$ 711,405,000		$ 711,405,000			$ 762,004,000

Allowance for Losses on Loans_3

Allowance for Losses on Loans - Internally Assigned Grade (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Mar. 31, 2021	Sep. 30, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	$ 13,208,075	$ 12,959,272
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	$ 12,493,123	$ 12,303,135
Pass | Accounts Receivable | Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
Total grade as a % of total loans	94.59%	94.94%
Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	$ 138,062	$ 247,543
Special mention | Accounts Receivable | Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
Total grade as a % of total loans	1.05%	1.91%
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	$ 576,890	$ 408,594
Substandard | Accounts Receivable | Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
Total grade as a % of total loans	4.37%	3.15%
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	$ 0	$ 0
Doubtful | Accounts Receivable | Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
Total grade as a % of total loans	0.00%	0.00%
Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	$ 0	$ 0
Loss | Accounts Receivable | Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
Total grade as a % of total loans	0.00%	0.00%
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	$ 7,726,098	$ 7,044,426
Commercial loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	7,042,556	6,412,415
Commercial loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	137,873	247,351
Commercial loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	545,669	384,660
Commercial loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Commercial loans | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Commercial loans | Multi-family
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	1,987,120	1,538,240
Commercial loans | Multi-family | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	1,918,072	1,506,692
Commercial loans | Multi-family | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	10,586	13,721
Commercial loans | Multi-family | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	58,462	17,827
Commercial loans | Multi-family | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Commercial loans | Multi-family | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Commercial loans | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	2,211,065	1,884,688
Commercial loans | Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	1,937,033	1,681,230
Commercial loans | Commercial real estate | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	62,847	92,184
Commercial loans | Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	211,185	111,274
Commercial loans | Commercial real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Commercial loans | Commercial real estate | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Commercial loans | Commercial & industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	2,452,585	2,115,513
Commercial loans | Commercial & industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	2,173,851	1,898,709
Commercial loans | Commercial & industrial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	48,867	64,695
Commercial loans | Commercial & industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	229,867	152,109
Commercial loans | Commercial & industrial | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Commercial loans | Commercial & industrial | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Commercial loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	925,017	1,352,414
Commercial loans | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	881,202	1,187,786
Commercial loans | Construction | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	61,178
Commercial loans | Construction | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	43,815	103,450
Commercial loans | Construction | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Commercial loans | Construction | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Commercial loans | Land - acquisition & development
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	150,311	153,571
Commercial loans | Land - acquisition & development | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	132,398	137,998
Commercial loans | Land - acquisition & development | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	15,573	15,573
Commercial loans | Land - acquisition & development | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	2,340	0
Commercial loans | Land - acquisition & development | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Commercial loans | Land - acquisition & development | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	5,481,977	5,914,846
Consumer loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	5,450,567	5,890,720
Consumer loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	189	192
Consumer loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	31,221	23,934
Consumer loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	308,831	295,953
Consumer loans | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	308,831	295,953
Consumer loans | Construction | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | Construction | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | Construction | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | Construction | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | Single-family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	4,802,575	5,293,962
Consumer loans | Single-family residential | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	4,773,261	5,270,666
Consumer loans | Single-family residential | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	189	192
Consumer loans | Single-family residential | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	29,125	23,104
Consumer loans | Single-family residential | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | Single-family residential | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | Land - consumer lot loans
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	122,211	101,394
Consumer loans | Land - consumer lot loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	122,034	101,151
Consumer loans | Land - consumer lot loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | Land - consumer lot loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	177	243
Consumer loans | Land - consumer lot loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | Land - consumer lot loans | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | HELOC
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	145,066	140,222
Consumer loans | HELOC | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	143,167	139,646
Consumer loans | HELOC | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | HELOC | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	1,899	576
Consumer loans | HELOC | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | HELOC | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	103,294	83,315
Consumer loans | Consumer | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	103,274	83,304
Consumer loans | Consumer | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | Consumer | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	20	11
Consumer loans | Consumer | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	0	0
Consumer loans | Consumer | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	$ 0	$ 0

Allowance for Losses on Loans_4

Allowance for Losses on Loans - Credit Risk Profile Based on Payment Activity (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 13,208,075	$ 12,959,272
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	7,726,098	7,044,426
Commercial loans | Multi-family
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	1,987,120	1,538,240
Commercial loans | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	2,211,065	1,884,688
Commercial loans | Commercial & industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	2,452,585	2,115,513
Commercial loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	925,017	1,352,414
Commercial loans | Land - acquisition & development
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	150,311	153,571
Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	5,481,977	5,914,846
Consumer loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	308,831	295,953
Consumer loans | Single-family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	4,802,575	5,293,962
Consumer loans | Land - consumer lot loans
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	122,211	101,394
Consumer loans | HELOC
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	145,066	140,222
Consumer loans | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	103,294	83,315
Performing Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 13,168,120	$ 12,930,216
% of Total Loans	99.70%	99.80%
Performing Loans | Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 7,712,277	$ 7,038,657
% of Total Loans	99.80%	99.90%
Performing Loans | Commercial loans | Multi-family
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 1,987,120	$ 1,538,240
% of Total Loans	100.00%	100.00%
Performing Loans | Commercial loans | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 2,201,839	$ 1,880,917
% of Total Loans	99.60%	99.80%
Performing Loans | Commercial loans | Commercial & industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 2,451,753	$ 2,115,184
% of Total Loans	100.00%	100.00%
Performing Loans | Commercial loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 923,594	$ 1,350,745
% of Total Loans	99.80%	99.90%
Performing Loans | Commercial loans | Land - acquisition & development
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 147,971	$ 153,571
% of Total Loans	98.40%	100.00%
Performing Loans | Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 5,455,843	$ 5,891,559
% of Total Loans	99.50%	99.60%
Performing Loans | Consumer loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 308,831	$ 295,953
% of Total Loans	100.00%	100.00%
Performing Loans | Consumer loans | Single-family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 4,776,976	$ 5,271,531
% of Total Loans	99.50%	99.60%
Performing Loans | Consumer loans | Land - consumer lot loans
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 122,034	$ 101,151
% of Total Loans	99.90%	99.80%
Performing Loans | Consumer loans | HELOC
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 144,760	$ 139,669
% of Total Loans	99.80%	99.60%
Performing Loans | Consumer loans | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 103,242	$ 83,255
% of Total Loans	99.90%	99.90%
Non-Performing Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 39,955	$ 29,056
% of Total Loans	0.30%	0.20%
Non-Performing Loans | Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 13,821	$ 5,769
% of Total Loans	0.20%	0.10%
Non-Performing Loans | Commercial loans | Multi-family
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 0	$ 0
% of Total Loans	0.00%	0.00%
Non-Performing Loans | Commercial loans | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 9,226	$ 3,771
% of Total Loans	0.40%	0.20%
Non-Performing Loans | Commercial loans | Commercial & industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 832	$ 329
% of Total Loans	0.00%	0.00%
Non-Performing Loans | Commercial loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 1,423	$ 1,669
% of Total Loans	0.20%	0.10%
Non-Performing Loans | Commercial loans | Land - acquisition & development
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 2,340	$ 0
% of Total Loans	1.60%	0.00%
Non-Performing Loans | Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 26,134	$ 23,287
% of Total Loans	0.50%	0.40%
Non-Performing Loans | Consumer loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 0	$ 0
% of Total Loans	0.00%	0.00%
Non-Performing Loans | Consumer loans | Single-family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 25,599	$ 22,431
% of Total Loans	0.50%	0.40%
Non-Performing Loans | Consumer loans | Land - consumer lot loans
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 177	$ 243
% of Total Loans	0.10%	0.20%
Non-Performing Loans | Consumer loans | HELOC
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 306	$ 553
% of Total Loans	0.20%	0.40%
Non-Performing Loans | Consumer loans | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Amount	$ 52	$ 60
% of Total Loans	0.10%	0.10%

Fair Value Measurements - Recur

Fair Value Measurements - Recurring (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 2,438,902	$ 2,249,492
Total financial assets	2,946,799	2,976,860
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	2,438,902	2,249,492
Total financial assets	2,505,339	2,297,693
Total financial liabilities	9,714	90,129
Recurring | Client swap program hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	5,104	48,201
Derivative liabilities	5,104	48,201
Recurring | Commercial loan fair value hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	4,610	8,492
Recurring | Borrowings cash flow hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	59,198
Derivative liabilities		17,375
Recurring | Mortgage loan fair value hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	2,135
Derivative liabilities		16,061
Recurring | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	71,512	18,824
Recurring | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,183,977	936,917
Recurring | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	38,669	38,315
Recurring | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	380,115	287,184
Recurring | Agency pass-through certificates
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	764,629	968,252
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Total financial assets	0	0
Total financial liabilities	0	0
Recurring | Level 1 | Client swap program hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Recurring | Level 1 | Commercial loan fair value hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	0
Recurring | Level 1 | Borrowings cash flow hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0
Derivative liabilities		0
Recurring | Level 1 | Mortgage loan fair value hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0
Derivative liabilities
Recurring | Level 1 | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring | Level 1 | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring | Level 1 | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring | Level 1 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring | Level 1 | Agency pass-through certificates
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	2,438,902	2,249,492
Total financial assets	2,505,339	2,297,693
Total financial liabilities	9,714	90,129
Recurring | Level 2 | Client swap program hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	5,104	48,201
Derivative liabilities	5,104	48,201
Recurring | Level 2 | Commercial loan fair value hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	4,610	8,492
Recurring | Level 2 | Borrowings cash flow hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	59,198
Derivative liabilities		17,375
Recurring | Level 2 | Mortgage loan fair value hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	2,135
Derivative liabilities		16,061
Recurring | Level 2 | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	71,512	18,824
Recurring | Level 2 | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,183,977	936,917
Recurring | Level 2 | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	38,669	38,315
Recurring | Level 2 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	380,115	287,184
Recurring | Level 2 | Agency pass-through certificates
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	764,629	968,252
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Total financial assets	0	0
Total financial liabilities	0	0
Recurring | Level 3 | Client swap program hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Recurring | Level 3 | Commercial loan fair value hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	0
Recurring | Level 3 | Borrowings cash flow hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0
Derivative liabilities		0
Recurring | Level 3 | Mortgage loan fair value hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0
Derivative liabilities
Recurring | Level 3 | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring | Level 3 | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0
Recurring | Level 3 | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring | Level 3 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring | Level 3 | Agency pass-through certificates
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 0	$ 0

Fair Value Measurements - Nonre

Fair Value Measurements - Nonrecurring (Details) - Nonrecurring - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and real estate owned, fair value	$ 722	$ 2,485	$ 722	$ 2,485
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and real estate owned, fair value	0	0	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and real estate owned, fair value	0	0	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and real estate owned, fair value	722	2,485	722	2,485
Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and real estate owned, fair value	0	810	0	810
Impaired loans | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and real estate owned, fair value	0	0	0	0
Impaired loans | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and real estate owned, fair value	0	0	0	0
Impaired loans | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and real estate owned, fair value	0	810	0	810
Real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and real estate owned, fair value	722	1,675	722	1,675
Real estate owned | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and real estate owned, fair value	0	0	0	0
Real estate owned | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and real estate owned, fair value	0	0	0	0
Real estate owned | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and real estate owned, fair value	722	1,675	722	1,675
Changes measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains (losses) related to loans and real estate owned	123	(101)	32	(402)
Changes measurement | Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains (losses) related to loans and real estate owned	(25)	(246)	(69)	(545)
Changes measurement | Real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains (losses) related to loans and real estate owned	$ 148	$ 145	$ 101	$ 143

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value by Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	$ 2,438,902	$ 2,249,492
Held-to-maturity securities	507,897	727,368
FHLB and FRB stock	119,991	141,990
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	2,438,902	2,249,492
Held-to-maturity securities	494,089	705,838
Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	2,438,902	2,249,492
Held-to-maturity securities	507,897	727,368
Level 1 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	2,318,447	1,702,977
Level 1 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	2,318,447	1,702,977
Level 2 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
FHLB and FRB stock	119,991	141,990
Time deposits	3,590,755	3,973,192
FHLB advances	2,150,000	2,700,000
Level 2 | Carrying Amount | Client swap program hedges
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	5,104	48,201
Other liabilities	5,104	48,201
Level 2 | Carrying Amount | Mortgage loan fair value hedges
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	2,135	0
Other liabilities	0	16,061
Level 2 | Carrying Amount | Commercial loan fair value hedges
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	0	0
Other liabilities	4,610	8,492
Level 2 | Carrying Amount | Borrowings cash flow hedges
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	59,198	0
Other liabilities	0	17,375
Level 2 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
FHLB and FRB stock	119,991	141,990
Time deposits	3,543,588	3,963,203
FHLB advances	2,115,171	2,722,509
Level 2 | Estimated Fair Value | Client swap program hedges
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	5,104	48,201
Other liabilities	5,104	48,201
Level 2 | Estimated Fair Value | Mortgage loan fair value hedges
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	2,135	0
Other liabilities	0	16,061
Level 2 | Estimated Fair Value | Commercial loan fair value hedges
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	0	0
Other liabilities	4,610	8,492
Level 2 | Estimated Fair Value | Borrowings cash flow hedges
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	59,198	0
Other liabilities	0	17,375
Level 3 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans receivable	13,035,423	12,792,317
Level 3 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans receivable	13,419,101	13,392,089
U.S. government and agency securities | Level 2 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	71,512	18,824
U.S. government and agency securities | Level 2 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	71,512	18,824
Asset-backed securities | Level 2 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	1,183,977	936,917
Asset-backed securities | Level 2 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	1,183,977	936,917
Municipal bonds | Level 2 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	38,669	38,315
Municipal bonds | Level 2 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	38,669	38,315
Corporate debt securities | Level 2 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	380,115	287,184
Corporate debt securities | Level 2 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	380,115	287,184
Agency pass-through certificates
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	503,723	720,516
Agency pass-through certificates | Level 2 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	764,629	968,252
Held-to-maturity securities	489,915	698,934
Agency pass-through certificates | Level 2 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	764,629	968,252
Held-to-maturity securities	503,723	720,516
Commercial MBS
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	4,174	6,852
Commercial MBS | Level 2 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	4,174	6,904
Commercial MBS | Level 2 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	$ 4,174	$ 6,852

Fair Value Measurements - Inves

Fair Value Measurements - Investments by Contractual Maturity Date (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Amortized Cost, Available-for-sale securities
Amortized Cost	$ 2,392,676	$ 2,210,099
Gross Unrealized Gains / Losses, Available-for-sale securities
Gross unrealized gains	51,149	49,007
Gross unrealized loss	(4,923)	(9,614)
Fair Value, Available-for-sale securities
Fair value	$ 2,438,902	$ 2,249,492
Yield, Available-for-sale securities
Yield	1.80%	1.97%
Amortized Cost, Held-to-maturity securities
Held-to-maturity securities, amortized cost	$ 494,089	$ 705,838
Gross Unrealized Gains / Losses, Held-to-maturity securities
Held-to-maturity securities, gross unrealized gains	13,808	21,582
Held-to-maturity securities, gross unrealized losses	0	(52)
Fair Value, Held-to-maturity securities
Held-to-maturity securities, fair value	$ 507,897	$ 727,368
Yield, Held-to-maturity securities
Held-to-maturity securities, yield	3.14%	3.14%
Investments	$ 2,886,765	$ 2,915,937
Gross unrealized gains on investments	64,957	70,589
Gross unrealized losses on investments	(4,923)	(9,666)
Total financial assets	$ 2,946,799	$ 2,976,860
Yield on investments	2.02%	2.25%
U.S. government and agency securities
Amortized Cost, Available-for-sale securities
Amortized cost, 1 to 5 years	$ 54,992
Amortized cost, 5 to 10 years	15,897	$ 18,448
Gross Unrealized Gains / Losses, Available-for-sale securities
Gross unrealized gains, 1 to 5 years	516
Gross unrealized gains, 5 to 10 years	107	376
Gross unrealized losses, 1 to 5 years	0
Gross unrealized losses, 5 to 10 years	0	0
Fair Value, Available-for-sale securities
Fair value, 1 to 5 years	55,508
Fair value, 5 to 10 years	$ 16,004	$ 18,824
Yield, Available-for-sale securities
Yield, 1 to 5 years	0.50%
Yield, 5 to 10 years	2.05%	2.05%
Asset-backed securities
Amortized Cost, Available-for-sale securities
Amortized cost, 5 to 10 years	$ 102,141	$ 38,289
Amortized cost, over 10 years	1,071,530	906,489
Gross Unrealized Gains / Losses, Available-for-sale securities
Gross unrealized gains, 5 to 10 years	447	0
Gross unrealized gains, over 10 years	10,994	647
Gross unrealized losses, 5 to 10 years	(718)	(1,600)
Gross unrealized losses, over 10 years	(417)	(6,908)
Fair Value, Available-for-sale securities
Fair value, 5 to 10 years	101,870	36,689
Fair value, over 10 years	$ 1,082,107	$ 900,228
Yield, Available-for-sale securities
Yield, 5 to 10 years	0.68%	0.83%
Yield, over 10 years	1.07%	1.14%
Corporate debt securities
Amortized Cost, Available-for-sale securities
Amortized cost, within 1 year	$ 31,742	$ 54,209
Amortized cost, 1 to 5 years	195,442	128,289
Amortized cost, 5 to 10 years	65,888	97,157
Amortized cost, over 10 years	80,560
Gross Unrealized Gains / Losses, Available-for-sale securities
Gross unrealized gains, within 1 year	126	337
Gross unrealized gains, 1 to 5 years	7,120	3,366
Gross unrealized gains, 5 to 10 years	751	4,305
Gross unrealized gains, over 10 years	0
Gross unrealized losses, Within 1 year	(28)	(51)
Gross unrealized losses, 1 to 5 years	0	(428)
Gross unrealized losses, 5 to 10 years	(710)	0
Gross unrealized losses, over 10 years	(776)
Fair Value, Available-for-sale securities
Fair value, within 1 year	31,840	54,495
Fair value, 1 to 5 years	202,562	131,227
Fair value, 5 to 10 years	65,929	$ 101,462
Fair value, over 10 years	$ 79,784
Yield, Available-for-sale securities
Yield, within 1 year	1.98%	1.22%
Yield, 1 to 5 years	1.67%	1.78%
Yield, 5 to 10 years	3.14%	1.50%
Yield, over 10 years	3.44%
Municipal bonds due
Amortized Cost, Available-for-sale securities
Amortized cost, 1 to 5 years	$ 1,477	$ 1,461
Amortized cost, 5 to 10 years	5,797
Amortized cost, over 10 years	29,929	36,044
Gross Unrealized Gains / Losses, Available-for-sale securities
Gross unrealized gains, 1 to 5 years	28	36
Gross unrealized gains, 5 to 10 years	275
Gross unrealized gains, over 10 years	1,163	774
Gross unrealized losses, 1 to 5 years	0	0
Gross unrealized losses, 5 to 10 years	0
Gross unrealized losses, over 10 years	0	0
Fair Value, Available-for-sale securities
Fair value, 1 to 5 years	1,505	1,497
Fair value, 5 to 10 years	6,072
Fair value, over 10 years	$ 31,092	$ 36,818
Yield, Available-for-sale securities
Yield, 1 to 5 years	0.00%	0.00%
Yield, 5 to 10 years	0.27%
Yield, over 10 years	5.85%	5.40%
Agency pass-through certificates
Amortized Cost, Available-for-sale securities
Amortized cost, without single maturity date	$ 737,281	$ 929,713
Gross Unrealized Gains / Losses, Available-for-sale securities
Gross unrealized gains, without single maturity date	29,622	39,166
Gross unrealized losses, without single maturity date	(2,274)	(627)
Fair Value, Available-for-sale securities
Fair value, without single maturity date	$ 764,629	$ 968,252
Yield, Available-for-sale securities
Yield, without single maturity date	2.67%	2.82%
Amortized Cost, Held-to-maturity securities
Held-to-maturity securities, amortized cost	$ 489,915	$ 698,934
Gross Unrealized Gains / Losses, Held-to-maturity securities
Held-to-maturity securities, gross unrealized gains	13,808	21,582
Held-to-maturity securities, gross unrealized losses	0	0
Fair Value, Held-to-maturity securities
Held-to-maturity securities, fair value	$ 503,723	$ 720,516
Yield, Held-to-maturity securities
Held-to-maturity securities, yield	3.16%	3.16%
Commercial MBS
Amortized Cost, Held-to-maturity securities
Held-to-maturity securities, amortized cost	$ 4,174	$ 6,904
Gross Unrealized Gains / Losses, Held-to-maturity securities
Held-to-maturity securities, gross unrealized gains	0	0
Held-to-maturity securities, gross unrealized losses	0	(52)
Fair Value, Held-to-maturity securities
Held-to-maturity securities, fair value	$ 4,174	$ 6,852
Yield, Held-to-maturity securities
Held-to-maturity securities, yield	0.98%	1.02%

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2020	Jan. 01, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Held-to-maturity securities reclassified	$ 494,089,000		$ 705,838,000
Available-for-sale securities after reclassification	2,392,676,000		2,210,099,000
Available-for-sale securities purchased	522,454,000	$ 159,884,000
Proceeds from sales of available-for-sale securities	0	204,351,000
Held-to-maturity securities purchased	0	0
Proceeds from sale of held-to-maturity securities	$ 0	$ 0
Term of contractual due dates of substantially all mortgage-backed securities (in years)	10 years
Accrued interest for available-for-sale securities	$ 4,128,000		3,285,000
Accrued interest for held-to-maturity securities	1,269,000		$ 1,811,000
Mortgage-backed securities | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Held-to-maturity securities reclassified				$ (374,680,000)
Available-for-sale securities after reclassification				$ 374,680,000
Consumer loans | Single-family residential
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Foreclosed residential real estate properties held as REO	676,000
Real estate acquired through foreclosure	$ 3,134,000

Fair Value Measurements - Secur

Fair Value Measurements - Securities in Unrealized Loss Positions (Details) $ in Thousands	Mar. 31, 2021USD ($)security	Sep. 30, 2020USD ($)security
Debt Securities, Available-for-sale [Line Items]
Number of debt securities with unrealized loss | security	38	51
Available-for-sale securities
Less than 12 months, unrealized gross losses	$ (3,554)	$ (5,833)
12 months or more, unrealized gross losses	(1,369)	(3,781)
Total unrealized gross losses	(4,923)	(9,614)
Less than 12 months, fair value	260,916	675,518
12 months or more, fair value	157,632	285,161
Total, fair value	418,548	960,679
Held-to-maturity securities
Less than 12 months, unrealized gross losses	0	(52)
12 months or more, unrealized gross losses	0	0
Total unrealized gross losses	0	(52)
Less than 12 months, fair value	0	6,853
12 months or more, fair value	0	0
Total, fair value	0	6,853
Less than 12 months, unrealized gross losses	(3,554)	(5,885)
12 months or more, unrealized gross losses	(1,369)	(3,781)
Total unrealized gross losses	(4,923)	(9,666)
Less than 12 months, fair value	260,916	682,371
12 months or more, fair value	157,632	285,161
Total fair value	418,548	967,532
Corporate debt securities
Available-for-sale securities
Less than 12 months, unrealized gross losses	(1,514)	(74)
12 months or more, unrealized gross losses	0	(405)
Total unrealized gross losses	(1,514)	(479)
Less than 12 months, fair value	125,191	45,875
12 months or more, fair value	0	24,596
Total, fair value	125,191	70,471
Asset-backed securities
Available-for-sale securities
Less than 12 months, unrealized gross losses	(77)	(5,481)
12 months or more, unrealized gross losses	(1,058)	(3,027)
Total unrealized gross losses	(1,135)	(8,508)
Less than 12 months, fair value	80,046	587,746
12 months or more, fair value	125,681	204,369
Total, fair value	205,727	792,115
Mortgage-backed securities
Available-for-sale securities
Less than 12 months, unrealized gross losses	(1,963)	(278)
12 months or more, unrealized gross losses	(311)	(349)
Total unrealized gross losses	(2,274)	(627)
Less than 12 months, fair value	55,679	41,897
12 months or more, fair value	31,951	56,196
Total, fair value	$ 87,630	$ 98,093

Derivatives and Hedging Activ_3

Derivatives and Hedging Activities - Summary of Fair Value, Notional Amount and Balance Sheet Classification (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Other assets
Derivatives, Fair Value [Line Items]
Notional amount	$ 2,353,904	$ 656,074
Derivative assets, fair value	66,437	48,201
Other liabilities
Derivatives, Fair Value [Line Items]
Notional amount	744,822	2,849,390
Derivative liabilities, fair value	9,714	90,129
Client swap program hedges | Other assets
Derivatives, Fair Value [Line Items]
Notional amount	653,904	656,074
Derivative assets, fair value	5,104	48,201
Client swap program hedges | Other liabilities
Derivatives, Fair Value [Line Items]
Notional amount	653,904	656,074
Derivative liabilities, fair value	5,104	48,201
Commercial loan fair value hedges | Other assets
Derivatives, Fair Value [Line Items]
Notional amount	0	0
Derivative assets, fair value	0	0
Commercial loan fair value hedges | Other liabilities
Derivatives, Fair Value [Line Items]
Notional amount	90,918	93,316
Derivative liabilities, fair value	4,610	8,492
Mortgage loan fair value hedges | Other assets
Derivatives, Fair Value [Line Items]
Notional amount	500,000	0
Derivative assets, fair value	2,135	0
Mortgage loan fair value hedges | Other liabilities
Derivatives, Fair Value [Line Items]
Notional amount	0	500,000
Derivative liabilities, fair value	0	16,061
Borrowings cash flow hedges | Other assets
Derivatives, Fair Value [Line Items]
Notional amount	1,200,000	0
Derivative assets, fair value	59,198	0
Borrowings cash flow hedges | Other liabilities
Derivatives, Fair Value [Line Items]
Notional amount	0	1,600,000
Derivative liabilities, fair value	$ 0	$ 17,375

Derivatives and Hedging Activ_4

Derivatives and Hedging Activities - Impact of Fair Value Hedge Accounting on the Carrying Value of the Hedged Items (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Derivatives, Fair Value [Line Items]
Carrying value of hedged items	$ 1,934,688	$ 2,562,765
Cumulative gain (loss) fair value hedge adjustment included in carrying amount of hedged items	2,831	24,664
Loans Receivable
Derivatives, Fair Value [Line Items]
Carrying value of hedged items	1,934,688	2,562,765
Cumulative gain (loss) fair value hedge adjustment included in carrying amount of hedged items	2,831	24,664
Mortgage loan fair value hedges
Derivatives, Fair Value [Line Items]
Cumulative gain (loss) fair value hedge adjustment included in carrying amount of hedged items	(1,929)	16,049
Amortized cost basis of the hedged loans	500,000
Mortgage loan fair value hedges | Loans Receivable
Derivatives, Fair Value [Line Items]
Carrying value of hedged items	1,839,169	2,461,008
Commercial loan fair value hedges
Derivatives, Fair Value [Line Items]
Cumulative gain (loss) fair value hedge adjustment included in carrying amount of hedged items	4,760	8,615
Commercial loan fair value hedges | Loans Receivable
Derivatives, Fair Value [Line Items]
Carrying value of hedged items	$ 95,519	$ 101,757

Derivatives and Hedging Activ_5

Derivatives and Hedging Activities - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Derivative [Line Items]
Gain (loss) on termination of hedging derivatives	$ 14,110	$ 0	$ 14,110	$ 0
Interest Rate Swap One | Cash flow hedging | Designated as Hedging Instrument
Derivative [Line Items]
Notional amount of derivative terminated			$ 200,000
Effective interest rate of derivative terminated			1.37%
Interest Rate Swap | Minimum
Derivative [Line Items]
Derivative, maturities			1 year
Interest Rate Swap | Maximum
Derivative [Line Items]
Derivative, maturities			10 years
Interest Rate Swap | Weighted average
Derivative [Line Items]
Derivative, maturities			6 years 8 months 12 days
Interest Rate Swap Two | Cash flow hedging | Designated as Hedging Instrument
Derivative [Line Items]
Notional amount of derivative terminated			$ 200,000
Effective interest rate of derivative terminated			0.79%
Interest Rate Swap Three | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional amount of derivative terminated			$ 150,000
Effective interest rate of derivative terminated			2.91%

Derivatives and Hedging Activ_6

Derivatives and Hedging Activities - Impact of Derivative Instruments on AOCI (Details) - Pay fixed/receive floating swaps on borrowings cash flow hedges - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Derivative [Line Items]
Pay fixed/receive floating swaps on borrowings cash flow hedges	$ 70,565	$ (12,428)	$ 90,683	$ (9,313)
Reclassification adjustment of net (gain)/loss included in net income	(14,110)	0	(14,110)	0
Total pre-tax gain/(loss) recognized in AOCI	$ 56,455	$ (12,428)	$ 76,573	$ (9,313)

Derivatives and Hedging Activ_7

Derivatives and Hedging Activities - Gains/(Losses) on Derivative Instruments in Fair Value and Cash Flow Accounting Hedging Relationships (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Interest income on loans receivable	$ 132,757	$ 138,549	$ 266,428	$ 280,695
Interest expense on FHLB advances	(11,991)	(13,368)	(25,189)	(27,026)
Interest rate contracts | Interest income on loans receivable | Fair value hedging
Gain/(loss) on fair value hedging relationships:
Amounts related to interest settlements on derivatives	(1,563)	(112)	(3,104)	(186)
Recognized on derivatives	17,491	(24,676)	22,078	(19,984)
Recognized on hedged items	(17,377)	24,666	(21,833)	20,073
Net income/(expense) recognized on fair value hedges	(1,449)	(122)	(2,859)	(97)
Interest rate contracts | Interest expense on FHLB advances | Cash flow hedging
Gain/(loss) on cash flow hedging relationships:
Amounts related to interest settlements on derivatives	3,066	498	6,664	284
Reclassification adjustment of net (gain)/loss included in net income	14,110	0	14,110	0
Net income/(expense) recognized on cash flow hedges	$ 17,176	$ 498	$ 20,774	$ 284

Derivatives and Hedging Activ_8

Derivatives and Hedging Activities - Impact of Client Swap Program that are Not Designated in Accounting Hedges (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Client swap program hedges
Derivative [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	$ 0	$ 0	$ 0	$ 0
Other noninterest income | Pay fixed/receive floating swap
Derivative [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	40,929	(28,184)	53,305	(22,776)
Other noninterest income | Receive fixed/pay floating swap
Derivative [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	$ (40,929)	$ 28,184	$ (53,305)	$ 22,776

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Details)	6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue streams percentage, contract with customer	5.70%	4.70%

Commitment and Contingencies (D

Commitment and Contingencies (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in process	$ 1,982,225	$ 1,456,072
Off-balance-sheet credit reserve	26,500	25,000
Financing Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in process	$ 3,348,654	$ 2,738,095

Uncategorized Items - wfsl-2021

Label	Element	Value
Accounting Standards Update [Extensible List]	us-gaap_AccountingStandardsUpdateExtensibleList	us-gaap:AccountingStandardsUpdate201613Member