Basis of Presentation and Significant Accounting Policies (Policies)	3 Months Ended
Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Our independent registered public accounting firm has not audited our accompanying interim financial statements. We derived the condensed consolidated balance sheet at September 30, 2019 from the audited consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2019 (the “Fiscal 2019 Form 10-K”). In the opinion of our management, the condensed consolidated financial statements reflect all adjustments, which are of a normal recurring nature, necessary for a fair presentation of our statements of income for the three months ended December 31, 2019 and December 31, 2018, our statements of comprehensive income for the three months ended December 31, 2019 and December 31, 2018, our balance sheets at December 31, 2019 and September 30, 2019, our statements of cash flows for the three months ended December 31, 2019 and December 31, 2018, and our statements of equity for the three months ended December 31, 2019 and December 31, 2018. We have condensed or omitted certain notes and other information from the interim financial statements presented in this report. Therefore, these interim financial statements should be read in conjunction with the Fiscal 2019 Form 10-K. The results for the three months ended December 31, 2019 are not necessarily indicative of results that may be expected for the full year.
Significant Accounting Policies	Significant Accounting Policies See “Note 1. Description of Business and Summary of Significant Accounting Policies” of the Notes to Consolidated Financial Statements section in the Fiscal 2019 Form 10-K for a summary of our significant accounting policies.
New Accounting Standards - Recently Adopted	New Accounting Standards — Recently Adopted In February 2018, the FASB issued Accounting Standards Update (“ASU”) 2018-02, “Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income”. The amendments in this update provide financial statement preparers with an option to reclassify stranded tax effects within accumulated other comprehensive income to retained earnings in the period of adoption or retrospectively in each period in which the effect of the change in the U.S. federal corporate income tax rate in the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Tax Act”) (or portion thereof) is recorded. We adopted the provisions of this ASU on October 1, 2019. Upon adoption, we elected to reclassify stranded tax effects of the Tax Act within accumulated other comprehensive income to retained earnings. The reclassification of stranded tax effects from accumulated other comprehensive income increased retained earnings by $73.4 million, all of which related to our employee benefit plans. In February 2016, the FASB issued ASU 2016-02 “Leases”, which is codified in Accounting Standards Codification (“ASC”) 842 “Leases” (“ASC 842”) and supersedes current lease guidance in ASC 840 “Leases”. These provisions require lessees to put a ROU asset and lease liability on their balance sheet for operating and financing leases that have a term of more than one year. Expense will be recognized in the income statement similar to current accounting guidance. For lessors, this ASU modifies the classification criteria and the accounting for sales-type and direct financing leases. Entities will need to disclose qualitative and quantitative information about their leases, including characteristics and amounts recognized in the financial statements. These provisions are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. We adopted the provisions of ASC 842 on October 1, 2019 using the modified retrospective approach and as a result did not restate prior periods. We elected the package of three practical expedients permitted within the standard pursuant to which we did not reassess initial direct costs, lease classification or whether our contracts contain or are leases. We also made an accounting policy election to not recognize ROU assets and liability for leases with a term of 12 months or less unless the lease includes an option to renew or purchase the underlying asset that are reasonably certain to be exercised. The adoption of ASC 842 resulted in the recognition of ROU assets of $731.1 million (net of deferred rent and favorable/unfavorable lease liabilities) with corresponding operating lease liabilities of $783.9 million. The condensed consolidated financial statements for the period ended December 31, 2019 are presented under the new standard, while comparative periods presented have not been adjusted and continue to be reported in accordance with the previous standard.
New Accounting Standards - Recently Issued	New Accounting Standards - Recently Issued See “Note 1. Description of Business and Summary of Significant Accounting Policies — New Accounting Standards — Recently Issued” of the Notes to Consolidated Financial Statements section of the Fiscal 2019 Form 10-K for information on new accounting standards issued prior to the beginning of fiscal 2020 but not yet adopted and where we do not expect that the adoption will have a material effect on our consolidated financial statements. Below is a description of new accounting standards for which we (i) are in the process of evaluating the impact on our consolidated financial statements or (ii) have determined that the new standard could have a material impact on our consolidated financial statements. We have not elected to early adopt any of the new accounting standards described below to the extent early adoption is permitted. In December 2019, the Financial Accounting Standards Board (“FASB”) issued ASU 2019-12 “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes”. This ASU simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740 under Generally Accepted Accounting Principles (“GAAP”). This ASU also improves consistent application of and simplifies GAAP for other areas of Topic 740 by clarifying and amending existing guidance. This ASU is effective for fiscal years beginning after December 15, 2020 and interim periods within those fiscal years. Early adoption is permitted. We are evaluating the impact of this ASU. In October 2018, the FASB issued ASU 2018-17 “Consolidation: Targeted Improvements to Related Party Guidance for Variable Interest Entities.” This ASU changes how entities evaluate decision-making fees under the variable interest entity guidance. To determine whether decision-making fees represent a variable interest, an entity considers indirect interests held through related parties under common control on a proportionate basis, rather than in their entirety, as currently required under GAAP. This ASU is effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. Early adoption is permitted. We are evaluating the impact of this ASU. In October 2018, the FASB issued ASU 2018-18 “Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606”, which provides targeted amendments to ASC 808, “Collaborative arrangements” (“ASC 808”) and ASC 606 “Revenue from Contracts with Customers” (“ASC 606”). The amendments in this ASU require transactions between participants in a collaborative arrangement to be accounted for under ASC 606 when the counterparty is a customer. This ASU precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue from contracts with customers if the counterparty is not a customer for that transaction. This ASU also amends ASC 808 to refer to the unit-of-account guidance in ASC 606 and requires it to be used only when assessing whether a transaction is in scope of ASC 606. This ASU is effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. Early adoption is permitted. We do not expect the adoption of this ASU to have a material impact on our consolidated financial statements. In August 2018, the FASB issued ASU 2018-15 “Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): 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 (and hosting arrangements that include an internal-use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected by these amendments. The provisions may be adopted prospectively or retrospectively. This ASU is effective for fiscal years, including interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted. We are evaluating the impact of this ASU. In August 2018, the FASB issued ASU 2018-14 “Compensation – Retirement Benefits – Defined Benefit Plans – General (Subtopic 715-20): Changes to the Disclosure Requirements for Defined Benefit Plans”. The amendments in this ASU modify the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans to remove disclosures that no longer are considered cost beneficial, clarify the specific requirements of disclosures and add disclosure requirements identified as relevant. These provisions will be applied retrospectively. This ASU is effective for fiscal years ending after December 15, 2020. Early adoption is permitted. We are evaluating the impact of this ASU. In June 2016, the FASB issued ASU 2016-13 “Financial Instruments – Credit losses: Measurement of Credit Losses on financial Instruments (Topic 326)” (“ASU 2016-13”), which modifies the measurement of expected credit losses of certain financial instruments. The ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and will be applied as a cumulative effect adjustment to retained earnings as of the beginning of the first reporting period for which the guidance is effective. In April 2019, the FASB issued ASU 2019-04 “Codification Improvements to Topic 326, Financial Instruments – Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments” (“ASU 2019-04”), which addresses issues related to accrued interest receivable balances, recoveries, variable interest rates and prepayments, among other things. In May 2019, the FASB issued ASU 2019-05 “Financial Instruments – Credit Losses (Topic 326): Targeted Transition Relief” (“ASU 2019-05”), which provides targeted transition relief allowing entities to make an irrevocable one-time election upon adoption of the new credit losses standard to measure financial assets previously measured at amortized cost (except held-to-maturity securities) using the fair value option. In November 2019, the FASB issued ASU 2019-11 “Codification Improvements to Topic 326, Financial Instruments – Credit Losses” (“ASU 2019-11”), which makes certain narrow-scope amendments to Topic 326, including allowing entities to exclude accrued interest amounts from various required disclosures under Topic 326. The provisions of ASU 2019-04, ASU 2019-05 and ASU 2019-11 related to Topic 326 are effective concurrent with the adoption of ASU 2016-13. We are evaluating the impact of these ASUs.

Basis of Presentation and Significant Accounting Policies (Policies)

3 Months Ended

Dec. 31, 2019

Our independent registered public accounting firm has not audited our accompanying interim financial statements. We derived the condensed consolidated balance sheet at September 30, 2019 from the audited consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2019 (the “Fiscal 2019 Form 10-K”). In the opinion of our management, the condensed consolidated financial statements reflect all adjustments, which are of a normal recurring nature, necessary for a fair presentation of our statements of income for the three months ended December 31, 2019 and December 31, 2018, our statements of comprehensive income for the three months ended December 31, 2019 and December 31, 2018, our balance sheets at December 31, 2019 and September 30, 2019, our statements of cash flows for the three months ended December 31, 2019 and December 31, 2018, and our statements of equity for the three months ended December 31, 2019 and December 31, 2018.

We have condensed or omitted certain notes and other information from the interim financial statements presented in this report. Therefore, these interim financial statements should be read in conjunction with the Fiscal 2019 Form 10-K. The results for the three months ended December 31, 2019 are not necessarily indicative of results that may be expected for the full year.

Significant Accounting Policies

See “Note 1. Description of Business and Summary of Significant Accounting Policies” of the Notes to Consolidated Financial Statements section in the Fiscal 2019 Form 10-K for a summary of our significant accounting policies.

New Accounting Standards - Recently Adopted

New Accounting Standards — Recently Adopted

In February 2018, the FASB issued Accounting Standards Update (“ASU”) 2018-02, “Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income”. The amendments in this update provide financial statement preparers with an option to reclassify stranded tax effects within accumulated other comprehensive income to retained earnings in the period of adoption or retrospectively in each period in which the effect of the change in the U.S. federal corporate income tax rate in the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Tax Act”) (or portion thereof) is recorded. We adopted the provisions of this ASU on October 1, 2019. Upon adoption, we elected to reclassify stranded tax effects of the Tax Act within accumulated other comprehensive income to retained earnings. The reclassification of stranded tax effects from accumulated other comprehensive income increased retained earnings by $73.4 million, all of which related to our employee benefit plans.

In February 2016, the FASB issued ASU 2016-02 “Leases”, which is codified in Accounting Standards Codification (“ASC”) 842 “Leases” (“ASC 842”) and supersedes current lease guidance in ASC 840 “Leases”. These provisions require lessees to put a ROU asset and lease liability on their balance sheet for operating and financing

leases that have a term of more than one year. Expense will be recognized in the income statement similar to current accounting guidance. For lessors, this ASU modifies the classification criteria and the accounting for sales-type and direct financing leases. Entities will need to disclose qualitative and quantitative information about their leases, including characteristics and amounts recognized in the financial statements. These provisions are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years.

We adopted the provisions of ASC 842 on October 1, 2019 using the modified retrospective approach and as a result did not restate prior periods. We elected the package of three practical expedients permitted within the standard pursuant to which we did not reassess initial direct costs, lease classification or whether our contracts contain or are leases. We also made an accounting policy election to not recognize ROU assets and liability for leases with a term of 12 months or less unless the lease includes an option to renew or purchase the underlying asset that are reasonably certain to be exercised. The adoption of ASC 842 resulted in the recognition of ROU assets of $731.1 million (net of deferred rent and favorable/unfavorable lease liabilities) with corresponding operating lease liabilities of $783.9 million. The condensed consolidated financial statements for the period ended December 31, 2019 are presented under the new standard, while comparative periods presented have not been adjusted and continue to be reported in accordance with the previous standard.

New Accounting Standards - Recently Issued

See “Note 1. Description of Business and Summary of Significant Accounting Policies — New Accounting Standards — Recently Issued” of the Notes to Consolidated Financial Statements section of the Fiscal 2019 Form 10-K for information on new accounting standards issued prior to the beginning of fiscal 2020 but not yet adopted and where we do not expect that the adoption will have a material effect on our consolidated financial statements. Below is a description of new accounting standards for which we (i) are in the process of evaluating the impact on our consolidated financial statements or (ii) have determined that the new standard could have a material impact on our consolidated financial statements. We have not elected to early adopt any of the new accounting standards described below to the extent early adoption is permitted.

In December 2019, the Financial Accounting Standards Board (“FASB”) issued ASU 2019-12 “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes”. This ASU simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740 under Generally Accepted Accounting Principles (“GAAP”). This ASU also improves consistent application of and simplifies GAAP for other areas of Topic 740 by clarifying and amending existing guidance. This ASU is effective for fiscal years beginning after December 15, 2020 and interim periods within those fiscal years. Early adoption is permitted. We are evaluating the impact of this ASU.

In October 2018, the FASB issued ASU 2018-17 “Consolidation: Targeted Improvements to Related Party Guidance for Variable Interest Entities.” This ASU changes how entities evaluate decision-making fees under the variable interest entity guidance. To determine whether decision-making fees represent a variable interest, an entity considers indirect interests held through related parties under common control on a proportionate basis, rather than in their entirety, as currently required under GAAP. This ASU is effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. Early adoption is permitted. We are evaluating the impact of this ASU.

In October 2018, the FASB issued ASU 2018-18 “Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606”, which provides targeted amendments to ASC 808, “Collaborative

arrangements” (“ASC 808”) and ASC 606 “Revenue from Contracts with Customers” (“ASC 606”). The amendments in this ASU require transactions between participants in a collaborative arrangement to be accounted for under ASC 606 when the counterparty is a customer. This ASU precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue from contracts with customers if the counterparty is not a customer for that transaction. This ASU also amends ASC 808 to refer to the unit-of-account guidance in ASC 606 and requires it to be used only when assessing whether a transaction is in scope of ASC 606. This ASU is effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. Early adoption is permitted. We do not expect the adoption of this ASU to have a material impact on our consolidated financial statements.

In August 2018, the FASB issued ASU 2018-15 “Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): 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 (and hosting arrangements that include an internal-use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected by these amendments. The provisions may be adopted prospectively or retrospectively. This ASU is effective for fiscal years, including interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted. We are evaluating the impact of this ASU.

In August 2018, the FASB issued ASU 2018-14 “Compensation – Retirement Benefits – Defined Benefit Plans – General (Subtopic 715-20): Changes to the Disclosure Requirements for Defined Benefit Plans”. The amendments in this ASU modify the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans to remove disclosures that no longer are considered cost beneficial, clarify the specific requirements of disclosures and add disclosure requirements identified as relevant. These provisions will be applied retrospectively. This ASU is effective for fiscal years ending after December 15, 2020. Early adoption is permitted. We are evaluating the impact of this ASU.

In June 2016, the FASB issued ASU 2016-13 “Financial Instruments – Credit losses: Measurement of Credit Losses on financial Instruments (Topic 326)” (“ASU 2016-13”), which modifies the measurement of expected credit losses of certain financial instruments. The ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and will be applied as a cumulative effect adjustment to retained earnings as of the beginning of the first reporting period for which the guidance is effective. In April 2019, the FASB issued ASU 2019-04 “Codification Improvements to Topic 326, Financial Instruments – Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments” (“ASU 2019-04”), which addresses issues related to accrued interest receivable balances, recoveries, variable interest rates and prepayments, among other things. In May 2019, the FASB issued ASU 2019-05 “Financial Instruments – Credit Losses (Topic 326): Targeted Transition Relief” (“ASU 2019-05”), which provides targeted transition relief allowing entities to make an irrevocable one-time election upon adoption of the new credit losses standard to measure financial assets previously measured at amortized cost (except held-to-maturity securities) using the fair value option. In November 2019, the FASB issued ASU 2019-11 “Codification Improvements to Topic 326, Financial Instruments – Credit Losses” (“ASU 2019-11”), which makes certain narrow-scope amendments to Topic 326, including allowing entities to exclude accrued interest amounts from various required disclosures under Topic 326. The provisions of ASU 2019-04, ASU 2019-05 and ASU 2019-11 related to Topic 326 are effective concurrent with the adoption of ASU 2016-13. We are evaluating the impact of these ASUs.