Summary of Significant Accounting Policies (Policies)	9 Months Ended
Jun. 30, 2018
Accounting Policies [Abstract]
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. Certain amounts in the financial statements from prior periods have been reclassified to conform to the current financial statement presentation. The information included in this Form 10-Q should be read in conjunction with the financial statements and related notes in the Company's 2017 Annual Report on Form 10-K (“2017 Annual Financial Statements”). Interim results are not necessarily indicative of results for a full year.
Off-Balance-Sheet Credit Exposures	The Company estimates losses on off-balance-sheet credit exposures by allocating a loss percentage derived from historical loss factors for each asset class.
New Accounting Pronouncements	In August 2017, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The ASU expands and refines hedge accounting for both financial and non-financial risk components, aligns the recognition and presentation of the effects of hedging instruments and hedge items in the financial statements, and includes certain targeted improvements to ease the application of current guidance related to the assessment of hedge effectiveness. The effective date of the new standard for public companies is for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The new standard must be adopted using a modified retrospective transition with a cumulative effect adjustment recorded to opening retained earnings as of the initial adoption date. The Company does not anticipate that this guidance will have a material impact on its consolidated financial statements. In March 2017, the FASB issued ASU 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20), Premium Amortization on Purchased Callable Debt Securities. The ASU shortens the amortization period for certain callable debt securities held at a premium. Specifically, the amendments require the premium to be amortized to the earliest call date. The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. The ASU is effective for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted, including adoption in an interim period. If an entity early adopts in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period. The amendments should be applied on a modified retrospective basis, with a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Company does not anticipate that this guidance will have a material impact on its consolidated financial statements. In February 2017, the FASB issued ASU 2017-05, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets. The ASU clarifies that a financial asset is within the scope of Subtopic 610-20 if it meets the definition of an in substance nonfinancial asset. The amendments also define the term in substance nonfinancial asset. The amendments clarify that nonfinancial assets within the scope of Subtopic 610-20 may include nonfinancial assets transferred within a legal entity to a counterparty. A contract that includes the transfer of ownership interests in one or more consolidated subsidiaries is within the scope of Subtopic 610-20 if substantially all of the fair value of the assets that are promised to the counterparty in a contract is concentrated in nonfinancial assets. The amendments clarify that an entity should identify each distinct nonfinancial asset or in substance nonfinancial asset promised to a counterparty and derecognize each asset when a counterparty obtains control of it. The ASU is effective for public business entities for annual periods beginning after December 15, 2017, and interim periods therein. Entities may use either a full or modified approach to adopt the ASU. The Company does not anticipate that this guidance will have a material impact on its consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash: a Consensus of the FASB Emerging Issues Task Force. This ASU requires a company’s cash flow statement to explain the changes during a reporting period of the totals for cash, cash equivalents, restricted cash, and restricted cash equivalents. Additionally, amounts for restricted cash and restricted cash equivalents are to be included with cash and cash equivalents if the cash flow statement includes a reconciliation of the total cash balances for a reporting period. This ASU is effective for public business entities for annual periods, including interim periods within those annual periods, beginning after December 15, 2017, with early application permitted. The Company does not anticipate that this guidance will have a material impact on its consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments. The amendments in this ASU address eight specific cash flow issues with the objective of reducing diversity in practice. The specific issues identified include: debt prepayments or extinguishment costs; contingent consideration payments made after a business combination; proceeds from the settlement of insurance claims; proceeds from the settlement of corporate-owned life insurance policies (including bank-owned life insurance policies); distributions received from equity method investees; beneficial interests in securitization transactions; and separately identifiable cash flows and application of the predominance principle. This ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within that reporting period; however, early adoption is permitted. The Company is currently evaluating the guidance to determine its adoption method and does not expect this guidance to have a material impact on its consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses. The amendments in this ASU were issued to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments that are not accounted for at fair value through net income, including loans held for investment, held-to-maturity debt securities, trade and other receivables, net investments in leases and other commitments to extend credit held by a reporting entity at each reporting date. The amendments require that financial assets measured at amortized cost be presented at the net amount expected to be collected, through an allowance for credit losses that is deducted from the amortized cost basis. The ASU eliminates the current framework of recognizing probable incurred losses and instead requires an entity to use its current estimate of all expected credit losses over the contractual life. The measurement of expected credit losses is based upon historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the financial assets. For purchased financial assets with a more-than-insignificant amount of credit deterioration since origination (“PCD assets”) that are measured at amortized cost, an allowance for expected credit losses is recorded as an adjustment to the cost basis of the asset. Subsequent changes in estimated cash flows would be recorded as an adjustment to the allowance and through the statement of income. Credit losses relating to available-for-sale debt securities will be recorded through an allowance for credit losses rather than as a direct write-down to the security's cost basis. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. For most debt securities, the transition approach requires a cumulative-effect adjustment to the statement of financial position as of the beginning of the first reporting period the guidance is effective. For other-than-temporarily impaired debt securities and PCD assets, the guidance will be applied prospectively. While the Company is currently in the process of evaluating the impact of the amended guidance on its consolidated financial statements, it currently expects the ALLL to increase upon adoption given that the allowance will be required to cover the full remaining expected life of the portfolio upon adoption, rather than the incurred loss model under current U.S. GAAP. The extent of this increase is still being evaluated and will depend on economic conditions and the composition of the Company’s loan and lease portfolio at the time of adoption. In February 2016, the FASB issued ASU 2016-02, Leases. The amendments require lessees to recognize a lease liability, which is a lessee's obligation to make lease payments arising from a lease, and a right-of-use asset, which is an asset that represents the lessee's right to use, or control the use of, a specified asset for the lease term. The guidance also simplifies the accounting for sale and leaseback transactions. The amendments are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early application is permitted upon issuance. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. The Company is currently in the process of accumulating the lease data necessary to apply the amended guidance. The Company is continuing to evaluate the impact of the amended guidance on its consolidated financial statements, but the effects of recognizing most operating leases is not expected to be material. The Company expects to recognize right-of-use assets and lease liabilities for substantially all of its operating lease commitments based on the present value of unpaid lease payments as of the date of adoption. In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities, to require all equity investments to be measured at fair value with changes in the fair value recognized through net income (other than those accounted for under equity method of accounting or those that result in consolidation of the investee). The amendments in this ASU also require an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. This ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within that reporting period. The Company does not expect this guidance to have a material impact on its consolidated financial statements. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). The guidance in this update supersedes the revenue recognition requirements in ASC Topic 605, Revenue Recognition, and most industry-specific guidance throughout the industry topics of the codification. For public companies, this update was to be effective for interim and annual periods beginning after December 15, 2016. However, in August 2015, the FASB issued ASU 2015-14, which delayed the effective date of ASU 2014-09 by one year and permits companies to voluntarily adopt the new standard as of the original effective date. The Company does not expect this guidance to have a material impact on its consolidated financial statements.

In August 2017, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The ASU expands and refines hedge accounting for both financial and non-financial risk components, aligns the recognition and presentation of the effects of hedging instruments and hedge items in the financial statements, and includes certain targeted improvements to ease the application of current guidance related to the assessment of hedge effectiveness. The effective date of the new standard for public companies is for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The new standard must be adopted using a modified retrospective transition with a cumulative effect adjustment recorded to opening retained earnings as of the initial adoption date. The Company does not anticipate that this guidance will have a material impact on its consolidated financial statements.

In March 2017, the FASB issued ASU 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20), Premium Amortization on Purchased Callable Debt Securities. The ASU shortens the amortization period for certain callable debt securities held at a premium. Specifically, the amendments require the premium to be amortized to the earliest call date. The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. The ASU is effective for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted, including adoption in an interim period. If an entity early adopts in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period. The amendments should be applied on a modified retrospective basis, with a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Company does not anticipate that this guidance will have a material impact on its consolidated financial statements.

In February 2017, the FASB issued ASU 2017-05, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets. The ASU clarifies that a financial asset is within the scope of Subtopic 610-20 if it meets the definition of an in substance nonfinancial asset. The amendments also define the term in substance nonfinancial asset. The amendments clarify that nonfinancial assets within the scope of Subtopic 610-20 may include nonfinancial assets transferred within a legal entity to a counterparty. A contract that includes the transfer of ownership interests in one or more consolidated subsidiaries is within the scope of Subtopic 610-20 if substantially all of the fair value of the assets that are promised to the counterparty in a contract is concentrated in nonfinancial assets. The amendments clarify that an entity should identify each distinct nonfinancial asset or in substance nonfinancial asset promised to a counterparty and derecognize each asset when a counterparty obtains control of it. The ASU is effective for public business entities for annual periods beginning after December 15, 2017, and interim periods therein. Entities may use either a full or modified approach to adopt the ASU. The Company does not anticipate that this guidance will have a material impact on its consolidated financial statements.

In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash: a Consensus of the FASB Emerging Issues Task Force. This ASU requires a company’s cash flow statement to explain the changes during a reporting period of the totals for cash, cash equivalents, restricted cash, and restricted cash equivalents. Additionally, amounts for restricted cash and restricted cash equivalents are to be included with cash and cash equivalents if the cash flow statement includes a reconciliation of the total cash balances for a reporting period. This ASU is effective for public business entities for annual periods, including interim periods within those annual periods, beginning after December 15, 2017, with early application permitted. The Company does not anticipate that this guidance will have a material impact on its consolidated financial statements.

In August 2016, the FASB issued ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments. The amendments in this ASU address eight specific cash flow issues with the objective of reducing diversity in practice. The specific issues identified include: debt prepayments or extinguishment costs; contingent consideration payments made after a business combination; proceeds from the settlement of insurance claims; proceeds from the settlement of corporate-owned life insurance policies (including bank-owned life insurance policies); distributions received from equity method investees; beneficial interests in securitization transactions; and separately identifiable cash flows and application of the predominance principle. This ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within that reporting period; however, early adoption is permitted. The Company is currently evaluating the guidance to determine its adoption method and does not expect this guidance to have a material impact on its consolidated financial statements.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses. The amendments in this ASU were issued to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments that are not accounted for at fair value through net income, including loans held for investment, held-to-maturity debt securities, trade and other receivables, net investments in leases and other commitments to extend credit held by a reporting entity at each reporting date. The amendments require that financial assets measured at amortized cost be presented at the net amount expected to be collected, through an allowance for credit losses that is deducted from the amortized cost basis. The ASU eliminates the current framework of recognizing probable incurred losses and instead requires an entity to use its current estimate of all expected credit losses over the contractual life. The measurement of expected credit losses is based upon historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the financial assets.

For purchased financial assets with a more-than-insignificant amount of credit deterioration since origination (“PCD assets”) that are measured at amortized cost, an allowance for expected credit losses is recorded as an adjustment to the cost basis of the asset. Subsequent changes in estimated cash flows would be recorded as an adjustment to the allowance and through the statement of income.

Credit losses relating to available-for-sale debt securities will be recorded through an allowance for credit losses rather than as a direct write-down to the security's cost basis.

The amendments in this ASU are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. For most debt securities, the transition approach requires a cumulative-effect adjustment to the statement of financial position as of the beginning of the first reporting period the guidance is effective. For other-than-temporarily impaired debt securities and PCD assets, the guidance will be applied prospectively. While the Company is currently in the process of evaluating the impact of the amended guidance on its consolidated financial statements, it currently expects the ALLL to increase upon adoption given that the allowance will be required to cover the full remaining expected life of the portfolio upon adoption, rather than the incurred loss model under current U.S. GAAP. The extent of this increase is still being evaluated and will depend on economic conditions and the composition of the Company’s loan and lease portfolio at the time of adoption.

In February 2016, the FASB issued ASU 2016-02, Leases. The amendments require lessees to recognize a lease liability, which is a lessee's obligation to make lease payments arising from a lease, and a right-of-use asset, which is an asset that represents the lessee's right to use, or control the use of, a specified asset for the lease term. The guidance also simplifies the accounting for sale and leaseback transactions. The amendments are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early application is permitted upon issuance. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. The Company is currently in the process of accumulating the lease data necessary to apply the amended guidance. The Company is continuing to evaluate the impact of the amended guidance on its consolidated financial statements, but the effects of recognizing most operating leases is not expected to be material. The Company expects to recognize right-of-use assets and lease liabilities for substantially all of its operating lease commitments based on the present value of unpaid lease payments as of the date of adoption.

In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities, to require all equity investments to be measured at fair value with changes in the fair value recognized through net income (other than those accounted for under equity method of accounting or those that result in consolidation of the investee). The amendments in this ASU also require an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. This ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within that reporting period. The Company does not expect this guidance to have a material impact on its consolidated financial statements.

In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). The guidance in this update supersedes the revenue recognition requirements in ASC Topic 605, Revenue Recognition, and most industry-specific guidance throughout the industry topics of the codification. For public companies, this update was to be effective for interim and annual periods beginning after December 15, 2016. However, in August 2015, the FASB issued ASU 2015-14, which delayed the effective date of ASU 2014-09 by one year and permits companies to voluntarily adopt the new standard as of the original effective date. The Company does not expect this guidance to have a material impact on its consolidated financial statements.