Basis of Presentation and Summary of Significant Accounting Policies (Policies)	6 Months Ended
Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The condensed consolidated financial statements included herein have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission ("SEC") and should be read in conjunction with the audited consolidated financial statements, and the notes to those statements, included in the Company's Form 10-K filed with the SEC on November 22, 2022. The Condensed Consolidated Balance Sheet as of September 30, 2022 was derived from audited financial statements which have been prepared in accordance with generally accepted accounting principles in the United States ("U.S. GAAP"). Certain information and footnote disclosures normally included in the consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations, although the Company believes that the disclosures made are adequate to make the information not misleading. In the opinion of the Company, the statements include all adjustments, which are of a normal, recurring nature, required for a fair presentation for the periods presented. The results of operations for interim periods are not necessarily indicative of the results for a full year, due to the seasonality of some of the Company's business activities and the possibility of changes in general economic conditions.The condensed consolidated financial statements include the accounts of the Company and all of its subsidiaries in which a controlling financial interest is maintained. All intercompany transactions and accounts have been eliminated.
New Accounting Standard Updates	New Accounting Standards Updates Adopted Standards (from most to least recent date of issuance) In December 2022, the Financial Accounting Standards Board ("FASB") issued an accounting standards update ("ASU") which defers the sunset date of Topic 848, Reference Rate Reform, to December 31, 2024 from December 31, 2022 and is effective for the Company upon issuance of the ASU. In January 2021, the FASB issued an ASU, which clarified certain optional expedients and exceptions for contract modifications and hedge accounting that may apply to derivatives that are affected by the discontinuance of LIBOR and the reference rate reform standard. In March 2020, the FASB issued an ASU which provided optional expedients that may be applied to assist with the discontinuance of LIBOR. The expedients allowed companies to ease the potential accounting burden when modifying contracts and hedging relationships that use LIBOR as a reference rate, if certain criteria are met. During fiscal 2020, the Company applied the optional expedient to assert probability of forecasted hedged transactions occurring on its interest rate swap derivative contracts regardless of any expected contract modifications related to reference rate reform. The Company may apply the optional expedients of this standard through December 31, 2024. The adoption of this guidance did not have a material impact on the condensed consolidated financial statements. In November 2021, the FASB issued an ASU which requires an entity to provide certain annual disclosures when they have received government assistance. The guidance was effective for the Company in the first quarter of fiscal 2023. The adoption of this guidance did not have a material impact on the condensed consolidated financial statements. Standards Not Yet Adopted (from most to least recent date of issuance) In September 2022, the FASB issued an ASU to enhance the transparency of supplier finance programs, which may be referred to as reverse factoring, payables finance or structured payables arrangements. The guidance will require that a buyer in a supplier finance program disclose the program's nature, activity and potential magnitude. The guidance is effective for the Company in the first quarter of fiscal 2024 and early adoption is permitted. The Company is currently evaluating the impact of this standard. In October 2021, the FASB issued an ASU which required that an entity (acquirer) recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with Accounting Standards Codification 606, Revenue from Contracts with Customers ("ASC 606") as if it had originated the contracts. The guidance is effective for the Company in the first quarter of fiscal 2024 and early adoption is permitted. The Company is currently evaluating the impact of this standard.Other new accounting pronouncements recently issued or newly effective were not applicable to the Company, did not have a material impact on the condensed consolidated financial statements or are not expected to have a material impact on the condensed consolidated financial statements.
Comprehensive Income	Comprehensive IncomeComprehensive income includes all changes to stockholders' equity during a period, except those resulting from investments by and distributions to stockholders. Components of comprehensive income include net income, pension plan adjustments (net of tax), changes in foreign currency translation adjustments (net of tax), changes in the fair value of cash flow hedges (net of tax) and changes to the share of any equity investees' comprehensive (loss) income (net of tax).
Currency Translation	Currency TranslationBeginning in fiscal 2018, Argentina was determined to have a highly inflationary economy. As a result, the Company remeasures the financial statements of Argentina's operations in accordance with the accounting guidance for highly inflationary economies. The impact of foreign currency transaction gains and losses during the three and six month periods of both fiscal 2023 and 2022 were immaterial to the condensed consolidated financial statements.
Current Assets	Current AssetsThe Company insures portions of its risk in general liability, automobile liability, workers’ compensation liability and property liability through a wholly owned captive insurance subsidiary (the "Captive"), to enhance its risk financing strategies. The Captive is subject to regulations within its domicile of Bermuda, including regulations established by the Bermuda Monetary Authority (the "BMA") relating to levels of liquidity and solvency as such concepts are defined by the BMA. The Captive was in compliance with these regulations as of March 31, 2023. These regulations may have the effect of limiting the Company's ability to access certain cash and cash equivalents held by the Captive for uses other than for the payment of its general liability, automobile liability, workers' compensation liability, property liability and related Captive costs.
Property and Equipment and Operating Lease Right-of-use Assets	Property and Equipment and Operating Lease Right-of-use Assets Starting in December 2022 and continuing into the second quarter of fiscal 2023, the Company completed a strategic review of certain administrative locations, taking into account facility capacity and current utilization, among other factors. Based on this review, the Company vacated or otherwise reduced its usage at certain of these locations, resulting in an analysis of the recoverability of the assets associated with the locations. As a result, for the three and six months ended March 31, 2023, the Company recorded an impairment charge of $3.3 million and $26.7 million, respectively, within its FSS United States and Uniform segments, which is included in "Cost of services provided (exclusive of depreciation and amortization)" in the Condensed Consolidated Statements of Income. For the three and six months ended March 31, 2023, the non-cash impairment charges within the FSS United States segment consisted of operating lease right-of-use assets of $0.7 million and $8.6 million, respectively, and property and equipment of zero and $10.4 million, respectively. For the three and six months ended March 31, 2023, the non-cash impairment charges within the Uniform segment consisted of operating lease right-of-use assets of $2.3 million and $7.1 million, respectively, and other costs of $0.3 million and $0.6 million, respectively.
Other Assets	Other Assets Other assets consist primarily of costs to obtain or fulfill contracts, including employee sales commissions and rental merchandise in-service, long-term receivables, investments in 50% or less owned entities and computer software costs. For investments in 50% or less owned entities accounted for under the equity method of accounting, the carrying amount as of March 31, 2023 and September 30, 2022 was $242.8 million and $224.5 million, respectively. For investments in 50% or less owned entities, other than those accounted for under the equity method of accounting, the Company measures these investments at cost, less any impairment and adjusted for changes in fair value resulting from observable price changes for an identical or a similar investment of the same issuer due to the lack of readily available fair values related to those investments.
Other Current and Noncurrent Liabilities	Other Current and Noncurrent Liabilities The Company is self-insured for obligations related to certain risks that are retained under the Company's casualty program, which includes general liability, automobile liability and workers' compensation liability, as well as for property liability and employee healthcare benefit programs. Reserves for retained costs associated with the casualty program are estimated through actuarial methods, with the assistance of third-party actuaries, using loss development assumptions based on the Company's claims history.
Fair Value of Financial Instruments	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Assets and liabilities recorded at fair value are classified based upon the level of judgment associated with the inputs used to measure their fair value. The hierarchical levels related to the subjectivity of the valuation inputs are defined as follows: • Level 1—inputs to the valuation methodology are quoted prices (unadjusted) for identical assets or liabilities in active markets • Level 2—inputs to the valuation methodology include quoted prices for similar assets and liabilities in active markets and inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument • Level 3—inputs to the valuation methodology are unobservable and significant to the fair value measurement Recurring Fair Value Measurements The Company's financial instruments consist primarily of cash and cash equivalents, accounts receivable, accounts payable, borrowings and derivatives. Management believes that the carrying value of cash and cash equivalents, accounts receivable and accounts payable are representative of their respective fair values. In conjunction with the fair value measurement of the derivative instruments, the Company made an accounting policy election to measure the credit risk of its derivative instruments that are subject to master netting agreements on a net basis by counterparty portfolio, as the gross values would not be materially different.

Basis of Presentation and Summary of Significant Accounting Policies (Policies)

6 Months Ended

Mar. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

The condensed consolidated financial statements included herein have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission ("SEC") and should be read in conjunction with the audited consolidated financial statements, and the notes to those statements, included in the Company's Form 10-K filed with the SEC on November 22, 2022. The Condensed Consolidated Balance Sheet as of September 30, 2022 was derived from audited financial statements which have been prepared in accordance with generally accepted accounting principles in the United States ("U.S. GAAP"). Certain information and footnote disclosures normally included in the consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations, although the Company believes that the disclosures made are adequate to make the information not misleading. In the opinion of the Company, the statements include all adjustments, which are of a normal, recurring nature, required for a fair presentation for the periods presented. The results of operations for interim periods are not necessarily indicative of the results for a full year, due to the seasonality of some of the Company's business activities and the possibility of changes in general economic conditions.The condensed consolidated financial statements include the accounts of the Company and all of its subsidiaries in which a controlling financial interest is maintained. All intercompany transactions and accounts have been eliminated.

New Accounting Standard Updates

New Accounting Standards Updates

Adopted Standards (from most to least recent date of issuance)

In December 2022, the Financial Accounting Standards Board ("FASB") issued an accounting standards update ("ASU") which defers the sunset date of Topic 848, Reference Rate Reform, to December 31, 2024 from December 31, 2022 and is effective for the Company upon issuance of the ASU. In January 2021, the FASB issued an ASU, which clarified certain optional expedients and exceptions for contract modifications and hedge accounting that may apply to derivatives that are affected by the discontinuance of LIBOR and the reference rate reform standard. In March 2020, the FASB issued an ASU which provided optional expedients that may be applied to assist with the discontinuance of LIBOR. The expedients allowed companies to ease the potential accounting burden when modifying contracts and hedging relationships that use LIBOR as a reference rate, if certain criteria are met. During fiscal 2020, the Company applied the optional expedient to assert probability of forecasted hedged transactions occurring on its interest rate swap derivative contracts regardless of any expected contract modifications related to reference rate reform. The Company may apply the optional expedients of this standard through December 31, 2024. The adoption of this guidance did not have a material impact on the condensed consolidated financial statements.

In November 2021, the FASB issued an ASU which requires an entity to provide certain annual disclosures when they have received government assistance. The guidance was effective for the Company in the first quarter of fiscal 2023. The adoption of this guidance did not have a material impact on the condensed consolidated financial statements.

Standards Not Yet Adopted (from most to least recent date of issuance)

In September 2022, the FASB issued an ASU to enhance the transparency of supplier finance programs, which may be referred to as reverse factoring, payables finance or structured payables arrangements. The guidance will require that a buyer in a supplier finance program disclose the program's nature, activity and potential magnitude. The guidance is effective for the Company in the first quarter of fiscal 2024 and early adoption is permitted. The Company is currently evaluating the impact of this standard.

In October 2021, the FASB issued an ASU which required that an entity (acquirer) recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with Accounting Standards Codification 606, Revenue

from Contracts with Customers ("ASC 606") as if it had originated the contracts. The guidance is effective for the Company in the first quarter of fiscal 2024 and early adoption is permitted. The Company is currently evaluating the impact of this standard.Other new accounting pronouncements recently issued or newly effective were not applicable to the Company, did not have a material impact on the condensed consolidated financial statements or are not expected to have a material impact on the condensed consolidated financial statements.

Comprehensive Income

Comprehensive IncomeComprehensive income includes all changes to stockholders' equity during a period, except those resulting from investments by and distributions to stockholders. Components of comprehensive income include net income, pension plan adjustments (net of tax), changes in foreign currency translation adjustments (net of tax), changes in the fair value of cash flow hedges (net of tax) and changes to the share of any equity investees' comprehensive (loss) income (net of tax).

Currency Translation

Currency TranslationBeginning in fiscal 2018, Argentina was determined to have a highly inflationary economy. As a result, the Company remeasures the financial statements of Argentina's operations in accordance with the accounting guidance for highly inflationary economies. The impact of foreign currency transaction gains and losses during the three and six month periods of both fiscal 2023 and 2022 were immaterial to the condensed consolidated financial statements.

Current Assets

Current AssetsThe Company insures portions of its risk in general liability, automobile liability, workers’ compensation liability and property liability through a wholly owned captive insurance subsidiary (the "Captive"), to enhance its risk financing strategies. The Captive is subject to regulations within its domicile of Bermuda, including regulations established by the Bermuda Monetary Authority (the "BMA") relating to levels of liquidity and solvency as such concepts are defined by the BMA. The Captive was in compliance with these regulations as of March 31, 2023. These regulations may have the effect of limiting the Company's ability to access certain cash and cash equivalents held by the Captive for uses other than for the payment of its general liability, automobile liability, workers' compensation liability, property liability and related Captive costs.

Property and Equipment and Operating Lease Right-of-use Assets

Starting in December 2022 and continuing into the second quarter of fiscal 2023, the Company completed a strategic review of certain administrative locations, taking into account facility capacity and current utilization, among other factors. Based on this review, the Company vacated or otherwise reduced its usage at certain of these locations, resulting in an analysis of the recoverability of the assets associated with the locations. As a result, for the three and six months ended March 31, 2023, the Company recorded an impairment charge of $3.3 million and $26.7 million, respectively, within its FSS United States and Uniform segments, which is included in "Cost of services provided (exclusive of depreciation and amortization)" in the Condensed Consolidated Statements of Income. For the three and six months ended March 31, 2023, the non-cash impairment charges within the FSS United States segment consisted of operating lease right-of-use assets of $0.7 million and $8.6 million, respectively, and property and equipment of zero and $10.4 million, respectively. For the three and six months ended March 31, 2023, the non-cash impairment charges within the Uniform segment consisted of operating lease right-of-use assets of $2.3 million and $7.1 million, respectively, and other costs of $0.3 million and $0.6 million, respectively.

Other Assets

Other assets consist primarily of costs to obtain or fulfill contracts, including employee sales commissions and rental merchandise in-service, long-term receivables, investments in 50% or less owned entities and computer software costs.

For investments in 50% or less owned entities accounted for under the equity method of accounting, the carrying amount as of March 31, 2023 and September 30, 2022 was $242.8 million and $224.5 million, respectively.

For investments in 50% or less owned entities, other than those accounted for under the equity method of accounting, the Company measures these investments at cost, less any impairment and adjusted for changes in fair value resulting from observable price changes for an identical or a similar investment of the same issuer due to the lack of readily available fair values related to those investments.

Other Current and Noncurrent Liabilities

The Company is self-insured for obligations related to certain risks that are retained under the Company's casualty program, which includes general liability, automobile liability and workers' compensation liability, as well as for property liability and employee healthcare benefit programs. Reserves for retained costs associated with the casualty program are estimated through actuarial methods, with the assistance of third-party actuaries, using loss development assumptions based on the Company's claims history.

Fair Value of Financial Instruments

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Assets and liabilities recorded at fair value are classified based upon the level of judgment associated with the inputs used to measure their fair value. The hierarchical levels related to the subjectivity of the valuation inputs are defined as follows:

• Level 1—inputs to the valuation methodology are quoted prices (unadjusted) for identical assets or liabilities in active markets

• Level 2—inputs to the valuation methodology include quoted prices for similar assets and liabilities in active markets and inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument

• Level 3—inputs to the valuation methodology are unobservable and significant to the fair value measurement

Recurring Fair Value Measurements

The Company's financial instruments consist primarily of cash and cash equivalents, accounts receivable, accounts payable, borrowings and derivatives. Management believes that the carrying value of cash and cash equivalents, accounts receivable and accounts payable are representative of their respective fair values. In conjunction with the fair value measurement of the derivative instruments, the Company made an accounting policy election to measure the credit risk of its derivative instruments that are subject to master netting agreements on a net basis by counterparty portfolio, as the gross values would not be materially different.