Earnings Per Share [Abstract] Anti-dilutive (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Revenue from Contract with Customer [Abstract] Revenue from External Customers by Products and Services [Table] Revenue from External Customers by Products and Services [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments Operating Segments [Member] Intersegment Eliminations Intersegment Eliminations [Member] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Janitorial Janitorial [Member] Janitorial [Member] Parking Parking [Member] Facility Services Facility Services [Member] Facility Services [Member] Building & Energy Solutions Building & Energy Solutions [Member] Building & Energy Solutions [Member] Airline Services Airline Services [Member] Airline Services [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Business & Industry Business and Industry [Member] Business and Industry [Member] Aviation Aviation [Member] Aviation [Member] Technology & Manufacturing Technology And Manufacturing [Member] Technology And Manufacturing [Member] Education Education [Member] Education [Member] Technical Solutions Technical Solutions [Member] Technical Solutions [Member] Revenue from External Customer [Line Items] Revenue from External Customer [Line Items] Revenues Revenue from Contract with Customer, Excluding Assessed Tax Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Table] Schedule Of Earnings Per Share Basic And Diluted By Common Class [Table] Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Table] Award Type [Axis] Award Type [Axis] Award Type [Domain] Award Type [Domain] RSUs Restricted Stock Units (RSUs) [Member] Stock options Share-based Payment Arrangement, Option [Member] Performance shares Performance Shares [Member] Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items] Schedule Of Earnings Per Share Basic And Diluted By Common Class [Line Items] Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items] Income from continuing operations Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent (Loss) income from discontinued operations, net of taxes Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent Net income Net Income (Loss) Attributable to Parent Weighted-average common and common equivalent shares outstanding—Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Effect of dilutive securities Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract] Effect of dilutive securities (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Weighted-average common and common equivalent shares outstanding—Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Net income per common share — Basic Earnings Per Share, Basic [Abstract] Income from continuing operations (usd per share) Income (Loss) from Continuing Operations, Per Basic Share Income (Loss) from discontinued operations (usd per share) Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share Net income (usd per share) Earnings Per Share, Basic Net income per common share — Diluted Earnings Per Share, Diluted [Abstract] Income from continuing operations (usd per share) Income (Loss) from Continuing Operations, Per Diluted Share Income (Loss) from discontinued operations (usd per share) Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share Net income (usd per share) Earnings Per Share, Diluted Revenue, remaining performance obligation, amount Revenue, Remaining Performance Obligation, Amount Revenue, remaining performance obligation, percentage Revenue, Remaining Performance Obligation, Percentage Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, remaining performance obligation, period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Segment Reporting [Abstract] Schedule of Financial Information by Reportable Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Schedule of Geographic Information Based on the Country in Which the Sale Originated Revenue from External Customers by Geographic Areas [Table Text Block] Accounting Policies [Abstract] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Computer equipment and software Computer Equipment And Software [Member] Computer Equipment And Software [Member] Machinery and other equipment Machinery and Equipment [Member] Transportation equipment Transportation Equipment [Member] Buildings Building [Member] Furniture and fixtures Furniture and Fixtures [Member] Statistical Measurement [Axis] Statistical Measurement [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Property, plant and equipment, estimated useful lives Property, Plant and Equipment, Useful Life Debt Disclosure [Abstract] Line of Credit Facility [Table] Line of Credit Facility [Table] Equity Components Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Interest Rate Swap, Maturity 4/30/2021 Interest Rate Swap, Maturity 4/30/2021 [Member] Interest Rate Swap, Maturity 4/30/2021 [Member] Interest Rate Swap, Maturity 10/31/2021 Interest Rate Swap, Maturity 10/31/2021 [Member] Interest Rate Swap, Maturity 10/31/2021 [Member] Interest Rate Swap, Maturity 4/30/2022 Interest Rate Swap, Maturity 4/30/2022 [Member] Interest Rate Swap, Maturity 4/30/2022 [Member] Interest Rate Swap, Maturity 9/1/2022 Interest Rate Swap, Maturity 9/1/2022 [Member] Interest Rate Swap, Maturity 9/1/2022 [Member] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Proceeds from termination of interest rate swaps Proceeds From Derivative Instrument, Operating Activities Proceeds From Derivative Instrument, Operating Activities Notional Amount Derivative, Notional Amount Derivative, fixed interest rate (percent) Derivative, Fixed Interest Rate Net gains from cash flow hedges recorded in accumulated other comprehensive loss, net of tax Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Tax related to amounts in accumulated other comprehensive loss AOCI Tax, Attributable to Parent Interest expense Interest Expense Interest expense, net of taxes Interest Expense, Net of Taxes Interest Expense, Net of Taxes Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, tax Interest Rate Cash Flow Hedge Gain (Loss) To Be Reclassified During Next 12 Months, Tax Interest Rate Cash Flow Hedge Gain (Loss) To Be Reclassified During Next 12 Months, Tax Income Tax Disclosure [Abstract] Operating Loss Carryforwards, Valuation Allowance Rollforward [Roll Forward] Operating Loss Carryforwards, Valuation Allowance Rollforward [Roll Forward] Operating Loss Carryforwards, Valuation Allowance Rollforward [Roll Forward] Valuation allowance at beginning of year Operating Loss Carryforwards, Valuation Allowance GCA acquisition Operation Loss Carryforwards, Valuation Allowance, Business Acquisition Operation Loss Carryforwards, Valuation Allowance, Business Acquisition Other, net Operation Loss Carryforwards, Valuation Allowance, Other Operation Loss Carryforwards, Valuation Allowance, Other Valuation allowance at end of year Stockholders' Equity Note [Abstract] Class of Treasury Stock [Table] Class of Treasury Stock [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Equity, Class of Treasury Stock [Line Items] Equity, Class of Treasury Stock [Line Items] Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Share repurchase program, authorized amount Stock Repurchase Program, Authorized Amount Share repurchase program, remaining authorized amount Stock Repurchase Program, Remaining Authorized Repurchase Amount Total number of shares repurchased (in shares) Stock Repurchased During Period, Shares Average price paid per share (usd per share) Stock Repurchase Average Cost Per Share Stock repurchase average cost per share. Total cash paid for share repurchase Stock Repurchased During Period, Value Income Taxes Income Tax Disclosure [Text Block] Statement of Financial Position [Abstract] Trade accounts receivable, allowance Accounts Receivable, Allowance for Credit Loss, Current Property, plant and equipment, accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Other intangible assets, accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Preferred stock, par value (usd per share) Preferred Stock, Par or Stated Value Per Share Common stock, par value (usd per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares issued (in shares) Common Stock, Shares, Issued Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Property, Plant and Equipment [Abstract] Capital leased assets, gross Capital Leased Assets, Gross Less: Accumulated depreciation Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation Total Capital Leases, Balance Sheet, Assets by Major Class, Net Insurance [Abstract] Schedule of Insurance Related Balances and Activity Schedule Of Insurance Related Balances And Activity [Table Text Block] Schedule Of Insurance Related Balances And Activity [Table Text Block] Schedule of Casualty Program Insurance Reserves Rollforward Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block] Schedule of Instruments Used to Collateralize Insurance Obligations Insurance Disclosure Table [Table Text Block] A tabular summary of letters of credit, surety bonds and restricted insurance deposits outstanding to collateralize self-insurance obligations. Preferred and Common Stock Stockholders' Equity Note Disclosure [Text Block] Fair Value Disclosures [Abstract] Schedule of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis Fair Value, by Balance Sheet Grouping [Table Text Block] Goodwill and Intangible Assets Disclosure [Abstract] Estimated amortization expense 2020 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months Estimated amortization expense 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Two Estimated amortization expense 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Three Estimated amortization expense 2023 Finite-Lived Intangible Assets, Amortization Expense, Year Four Estimated amortization expense 2024 Finite-Lived Intangible Assets, Amortization Expense, Year Five Quarterly Financial Information Disclosure [Abstract] Selected Quarterly Financial Data (Unaudited) Quarterly Financial Information [Text Block] Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] Government Services Government Services [Member] Government Services [Member] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Disposal Group, Disposed of by Sale, Not Discontinued Operations Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Impairment loss (recovery) Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down Business combination contingent consideration offer Disposal Group, Including Discontinued Operation, Amount Of Offer Disposal Group, Including Discontinued Operation, Amount Of Offer (Adjustments to) and proceeds from sale of business Proceeds from Divestiture of Businesses Gain on sale of government services business Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal Retirement Benefits [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Multiemployer Plan Type [Axis] Multiemployer Plan Type [Axis] Multiemployer Plans Type [Domain] Multiemployer Plans Type [Domain] Multiemployer Plans, Pension Plans Multiemployer Plans, Pension [Member] Multiemployer Plans, Postretirement Benefit Plans Multiemployer Plans, Postretirement Benefit [Member] Multiemployer Plan Name [Axis] Multiemployer Plan Name [Axis] Multiemployer Plan Name [Domain] Multiemployer Plan Name [Domain] Defined Contribution Plans Multiemployer Plans, Defined Contribution Plans [Member] Multiemployer Plans, Defined Contribution Plans [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Contributions by ABM Multiemployer Plan, Contributions by Employer Property, Plant and Equipment Property, Plant and Equipment Disclosure [Text Block] SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] Accounts receivable allowances SEC Schedule, 12-09, Allowance, Credit Loss [Member] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] Balance Beginning of Year SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount Charges to Costs and Expenses SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense Write-offs/Allowance Taken SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction Balance End of Year Revenue, Initial Application Period Cumulative Effect Transition [Table] Revenue, Initial Application Period Cumulative Effect Transition [Table] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Domain] Initial Application Period Cumulative Effect Transition [Domain] Under Historical Guidance Calculated under Revenue Guidance in Effect before Topic 606 [Member] Effect of Adoption Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2014-09 Accounting Standards Update 2014-09 [Member] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Operating expenses Cost of Goods and Services Sold Selling, general and administrative expenses Selling, General and Administrative Expense Income tax provision Income Tax Expense (Benefit) Net income Net income per common share — Basic (in usd per share) Net income per common share — Diluted (in usd per share) Basis of Presentation [Table] Basis Of Presentation [Table] Basis of Presentation [Table] Accounting Standards Update 2016-02 Accounting Standards Update 2016-02 [Member] Scenario [Axis] Scenario [Axis] Scenario [Domain] Scenario [Domain] Forecast Forecast [Member] Basis of Presentation [Line Items] Basis Of Presentation [Line Items] Basis of Presentation [Line Items] Ownership percentages Equity Method Investment, Ownership Percentage Investments in unconsolidated affiliates Equity Method Investments Other-than-temporary impairment Equity Method Investment, Other than Temporary Impairment Advertising expense Advertising Expense Finance Lease, Right-of-Use Asset Finance Lease, Right-of-Use Asset Finance Lease, Liability Finance Lease, Liability Credit Facility Debt And Derivative Instruments Disclosure [Text Block] The entire disclosure for the entity's debt and derivative instruments. Includes information about the amount of borrowings under the entity's line of credit and other matters important to the users of the financial statements and describes an entity's risk management strategies, derivatives in hedging activities and non-hedging derivative instruments, the assets, obligations, liabilities, revenues and expenses arising there from, and the amounts of and methodologies and assumptions used in determining the amounts of such items. Organization, Consolidation and Presentation of Financial Statements [Abstract] Number of industry groups Number Of Industry Groups Number Of Industry Groups Number of technical solution segments Number Of Technical Solution Segments Number Of Technical Solution Segments Share-based Payment Arrangement [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Beginning balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Performance adjustments (in shares) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Other In Period The change in the number of shares made during period on other than stock (or unit) options, as a result of the change in the probability of achieving the performance targets established under the plan. Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Ending balance (in shares) Weighted-Average Grant Date Fair Value per Share Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] Beginning balance (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Granted (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Vested (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Performance adjustments (usd per share) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Other In Period Weighted Average Grant Date Fair Value The weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that have fluctuated as a result of the change in the probability of achieving the performance targets established under the plan. Forfeited (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Ending balance (usd per share) Shares withheld for income taxes (in shares) Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation United States Income (Loss) from Continuing Operations before Income Taxes, Domestic Foreign Income (Loss) from Continuing Operations before Income Taxes, Foreign Income from continuing operations before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Current: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Current Federal Tax Expense (Benefit) State Current State and Local Tax Expense (Benefit) Foreign Current Foreign Tax Expense (Benefit) Deferred: Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Deferred Federal Income Tax Expense (Benefit) State Deferred State and Local Income Tax Expense (Benefit) Foreign Deferred Foreign Income Tax Expense (Benefit) Income tax (provision) benefit Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Measurement Frequency [Domain] Measurement Frequency [Domain] Fair Value Measurements, Recurring Fair Value, Recurring [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Fair Value, Inputs, Level 1 Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 Fair Value, Inputs, Level 3 [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Insurance deposits Restricted Cash and Cash Equivalents, Noncurrent Assets held in funded deferred compensation plan Deferred Compensation Plan Assets Credit facility Debt Instrument, Fair Value Disclosure Interest rate swaps liabilities Interest Rate Derivative Liabilities, at Fair Value Interest rate swaps assets Interest Rate Derivative Assets, at Fair Value Investments in auction rate securities Debt Securities, Available-for-sale Business Combinations [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Mechanical Solutions Inc (MSI) Mechanical Solutions Inc [Member] Mechanical Solutions Inc [Member] OFJ Connections Ltd (OFJ) OFJ Connections Ltd [Member] OFJ Connections Ltd [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Purchase price Business Combination, Consideration Transferred Contingent consideration liability Business Combination, Contingent Consideration, Liability Schedule II-Valuation and Qualifying Accounts SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Domain] Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Domain] Employee Stock Purchase Plan Employee Stock Purchase Plan [Member] Employee Stock Purchase Plan [Member] Weighted average fair value of granted purchase rights per share (usd per share) Weighted Average Fair Value of Stock Purchase Right Under Employee Stock Purchase Plan This element represents the weighted average fair value of each purchase right under the employee stock purchase plan. Common stock issued (in shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Fair value of common stock issued per share (usd per share) Stock Issued During Period Weighted Average Price Per Share Employee Stock Purchase Plans Weighted average price per share of common stock issued during the period as a result of an employee stock purchase plan. Aggregate purchases Stock Issued During Period, Value, Employee Stock Purchase Plan Schedule of Geographic Sources of Income From Continuing Operations Before Income Taxes Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Schedule of Components of Income Tax (Provision) Benefit Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Reconciliation of U.S. Statutory Tax Rate to Annual Effective Tax Rate Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Components of Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of Changes to the Deferred Tax Asset Valuation Allowance Summary of Operating Loss Carryforwards, Valuation Allowance Rollforward [Table Text Block] Summary of Operating Loss Carryforwards, Valuation Allowance Rollforward [Table Text Block] Reconciliation of Total Unrecognized Tax Benefits Summary of Income Tax Contingencies [Table Text Block] Exercisable rate Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Total unrecognized compensation cost, net of estimated forfeitures Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Weighted-average vesting period Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Fair value per share of awards granted (usd per share) Total fair value of RSUs vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value ASSETS Assets [Abstract] Current assets Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Trade accounts receivable, net of allowances of $22.4 and $19.2 at October 31, 2019 and 2018, respectively Contract with Customer, Asset, Net, Current Costs incurred in excess of amounts billed Accounts and Other Receivables, Net, Current Prepaid expenses Prepaid Expense, Current Other current assets Other Assets, Current Total current assets Assets, Current Other investments Other Investments Property, plant and equipment, net of accumulated depreciation of $199.5 and $153.9 at October 31, 2019 and 2018, respectively Property, Plant and Equipment, Net Other intangible assets, net of accumulated amortization of $309.0 and $250.4 at October 31, 2019 and 2018, respectively Finite-Lived Intangible Assets, Net Goodwill Goodwill Other noncurrent assets Other Assets, Noncurrent Total assets Assets LIABILITIES AND STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Current liabilities Liabilities, Current [Abstract] Current portion of long-term debt, net Long-term Debt, Current Maturities Trade accounts payable Accounts Payable, Current Accrued compensation Employee-related Liabilities, Current Accrued taxes—other than income Accrual for Taxes Other than Income Taxes, Current Insurance claims Self Insurance Reserve, Current Income taxes payable Accrued Income Taxes, Current Other accrued liabilities Other Accrued Liabilities, Current Total current liabilities Liabilities, Current Long-term debt, net Long-term Debt, Excluding Current Maturities Deferred income tax liability, net Deferred Income Tax Liabilities, Net Noncurrent insurance claims Self Insurance Reserve, Noncurrent Other noncurrent liabilities Other Liabilities, Noncurrent Noncurrent income taxes payable Accrued Income Taxes, Noncurrent Total liabilities Liabilities Commitments and contingencies Commitments and Contingencies Stockholders’ Equity Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, $0.01 par value; 500,000 shares authorized; none issued Preferred Stock, Value, Issued Common stock, $0.01 par value; 100,000,000 shares authorized; 66,571,427 and 66,004,361 shares issued and outstanding at October 31, 2019 and 2018, respectively Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Accumulated other comprehensive loss, net of taxes Accumulated Other Comprehensive Income (Loss), Net of Tax Retained earnings Retained Earnings (Accumulated Deficit) Total stockholders’ equity Stockholders' Equity Attributable to Parent Total liabilities and stockholders’ equity Liabilities and Equity Billed trade receivables Contract with Customer, Asset, Billed Trade Receivable, Net, Current Contract with Customer, Asset, Billed Trade Receivable, Net, Current Unbilled trade receivables Contract with Customer, Asset, Unbilled Trade Receivables, Net, Current Contract with Customer, Asset, Unbilled Trade Receivables, Net, Current Costs incurred in excess of amounts billed Contract with Customer, Asset, Costs Incurred in Excess of Amounts Billed, Current Contract with Customer, Asset, Costs Incurred in Excess of Amounts Billed, Current Capitalized commissions Contract with Customer, Asset, Capitalized Commissions Contract with Customer, Asset, Capitalized Commissions Capitalized contract price Contract with Customer, Asset, Increase (Decrease) for New Capitalized Costs Contract with Customer, Asset, Increase (Decrease) for New Capitalized Costs Capitalized contract cost, amortization Capitalized Contract Cost, Amortization Capitalized Contract Cost, Impairment Loss Capitalized Contract Cost, Impairment Loss Contract with Customer, Liabilities [Roll Forward] Contract with Customer, Liabilities [Roll Forward] Contract with Customer, Liabilities [Roll Forward] Contract liabilities, balance at beginning of period Contract with Customer, Liability, Current Additional contract liabilities Contract with Customer, Liability, Increase (Decrease) for Additional Contract Liabilities Contract with Customer, Liability, Increase (Decrease) for Additional Contract Liabilities Recognition of deferred revenue Contract with Customer, Liability, Revenue Recognized Contract liabilities, balance at end of period Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Principles of Consolidation Consolidation, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Prior Year Reclassifications Reclassification, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Trade Accounts Receivable and Allowance for Doubtful Accounts Receivable [Policy Text Block] Sales Allowance Allowance for Credit Losses [Text Block] Investments in Unconsolidated Affiliates Equity Method Investments [Policy Text Block] Investments in Auction Rate Securities Investment, Policy [Policy Text Block] Property, Plant and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Leases Lessee, Leases [Policy Text Block] Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Federal Energy Savings Performance Contract Receivables Revenue from Contract with Customer [Policy Text Block] Fair Value of Financial Instruments Fair Value Measurement, Policy [Policy Text Block] Acquisitions Business Combinations Policy [Policy Text Block] Discontinued Operations Discontinued Operations, Policy [Policy Text Block] Assets and liabilities held for sale Assets and Liabilities Held For Sale Policy [Policy Text Block] Assets and Liabilities Held For Sale Policy [Policy Text Block] Insurance Reserves Insurance And Self Insurance Policy [Policy Text Block] Insurance And Self Insurance Policy [Policy Text Block] Other Accrued Liabilities Other Accrued Liabilities Policy [Policy Text Block] Other Accrued Liabilities Policy [Policy Text Block] Other noncurrent liabilities Other Noncurrent Liabilities Policy [Policy Text Block] Other Noncurrent Liabilities Policy [Policy Text Block] Revenue Recognition Revenue [Policy Text Block] Restructuring and Related Expenses, Severance, Noncancelable Leases and Contractual Obligations, Other Costs Associated with Exit or Disposal Activities or Restructurings, Policy [Policy Text Block] Advertising Advertising Cost [Policy Text Block] Share-Based Compensation Compensation Related Costs, Policy [Policy Text Block] Taxes Collected from Clients and Remitted to Governmental Agencies Taxes Collected From Customers Policy [Policy Text Block] Taxes Collected From Customers Policy [Policy Text Block] Net Income Per Common Share Earnings Per Share, Policy [Policy Text Block] Contingencies and Litigation Commitments and Contingencies, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Recently Adopted and Issued Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Eurodollar Eurodollar [Member] Base Rate Base Rate [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving Credit Facility Revolving Credit Facility [Member] Standby letters of credit Standby Letters of Credit [Member] Swing Line Loan Swing Line Loan [Member] Swing Line Loan [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Line of Credit Line of Credit [Member] Term Loan Loans Payable [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Prior Credit Facility Prior Credit Facility [Member] Prior Credit Facility [Member] Credit Facility Credit Facility [Member] Credit Facility [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Line of credit, borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Line of credit facility, term Debt Instrument, Term Debt instrument, face amount Debt Instrument, Face Amount Borrowing capacity after initial year of term Line Of Credit Facility, Maximum Borrowing Capacity After Initial Year Of Term Line Of Credit Facility, Maximum Borrowing Capacity After Initial Year Of Term Variable interest rate Debt Instrument, Basis Spread on Variable Rate Weighted average interest rate Debt, Weighted Average Interest Rate Percentage of commitment fee on the unused portion of the Facility Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Leverage ratio Debt Instrument Covenant Total Leverage Ratio Debt Instrument Covenant Total Leverage Ratio Fixed charge coverage ratio Debt Instrument Covenant Fixed Charge Coverage Ratio Debt Instrument Covenant Fixed Charge Coverage Ratio Leverage ratio election option for four fiscal quarters in the event of material acquisition Debt Instrument, Covenant Total Leverage Ratio, Optional Ratio For Four Fiscal Quarters In Event Of Material Acquisition Debt Instrument, Covenant Total Leverage Ratio, Optional Ratio For Four Fiscal Quarters In Event Of Material Acquisition Deferred financing costs Debt Issuance Costs, Gross Share-Based Compensation Plans Share-based Payment Arrangement [Text Block] Investments, Debt and Equity Securities [Abstract] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Auction rate securities Auction Rate Securities [Member] Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Investments in auction rate securities, original principal amount Available-for-sale Debt Securities, Original Principal Amount This item represents the original cost of debt securities, which are categorized neither as held-to-maturity nor trading, excluding adjustments such as accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. Investment in auction rate securities, amortized cost basis Debt Securities, Available-for-sale, Amortized Cost Investments in auction rate securities, principal amount Interest rate reset interval Interest Rate Reset Interval The period of time in which the interest rates for auction rate securities reset through auctions. Unrealized holding gain (loss) on securities included in AOCL Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Significant Assumptions Used to Determine Fair Value of Auction Rate Securities Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Income Statement [Abstract] Restructuring and related expenses Restructuring Charges Amortization of intangible assets Amortization of Intangible Assets Impairment loss (recovery) Goodwill and Intangible Asset Impairment Operating profit Operating Income (Loss) Income from unconsolidated affiliates Income (Loss) from Equity Method Investments Interest expense Income from continuing operations before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income tax (provision) benefit Income from continuing operations (Loss) income from discontinued operations, net of taxes Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Interest rate swaps and other Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax Foreign currency translation Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Income tax benefit (provision) Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Weighted-average common and common equivalent shares outstanding Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic (in shares) Diluted (in shares) Restructuring and Related Activities [Abstract] Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Restructuring Type [Axis] Restructuring Type [Axis] Type of Restructuring [Domain] Type of Restructuring [Domain] External Support Fees External Support Fees [Member] External Support Fees [Member] Employee Severance Employee Severance [Member] Other Project Fees Other Project Fees [Member] Other Project Fees [Member] Lease Exit Lease Exit [Member] Lease Exit [Member] Asset Impairment Asset Impairment [Member] Asset Impairment [Member] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] Balance, beginning Restructuring Reserve Costs recognized Costs recognized Restructuring Charges, Including Adjustments Restructuring Charges, Including Adjustments Payments Payments for Restructuring Non-cash charges Restructuring Reserve, Settled without Cash Non-cash items Restructuring Reserve, Accrual Adjustment Balance, ending Segment and Geographic Information Segment Reporting Disclosure [Text Block] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Schedule of Selected Quarterly Financial Data Quarterly Financial Information [Table Text Block] Schedule of Information for the Plans Schedule of Defined Benefit Plans Disclosures [Table Text Block] Schedule of Multiemployer Pension Plans Schedule of Multiemployer Plans [Table Text Block] Schedule of Estimated Useful Lives of Property, Plant and Equipment Property, Plant, and Equipment, Estimated Useful Lives [Table Text Block] Property, Plant, and Equipment, Estimated Useful Lives [Table Text Block] Schedule of Management Reimbursement Revenue by Segment Management Revenue [Table Text Block] Management Revenue [Table Text Block] Schedule of New Accounting Pronouncements and Changes in Accounting Principles Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Cover page. Document Type Document Type Document Annual Report Document Annual Report Document Period End Date Document Period End Date Document Transition Report Document Transition Report Entity File Number Entity File Number Entity Registrant Name Entity Registrant Name Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province Entity Address, Postal Zip Code Entity Address, Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer 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Weighted-Average Remaining Contractual Term (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Weighted-Average Remaining Contractual Term, Outstanding (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Weighted-Average Remaining Contractual Term, Exercisable (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Share Based Compensation Arrangement By Share Based Payment Award Options Aggregate Intrinsic Value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Aggregate Intrinsic Value [Abstract] Aggregate Intrinsic Value, Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Aggregate Intrinsic Value, Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Equity Securities Equity Securities [Member] Fixed Income Funds Fixed Income Funds [Member] Cash and Cash Equivalents Cash and Cash Equivalents [Member] Net obligations Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position Projected benefit obligations Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation Fair value of assets Defined Benefit Plan, Plan Assets, Amount Target plan asset allocations Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Expected return on assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Expected future benefit payments Defined Benefit Plan, Expected Future Benefit Payments, Aggregate Defined Benefit Plan, Expected Future Benefit Payments, Aggregate Tax benefit, reduction resulting from enactment of the tax act Tax Cuts And Jobs Act, Income Tax Expense (Benefit) Tax Cuts And Jobs Act, Income Tax Expense (Benefit) One-time net tax act benefit related to Tax Act (usd per share) Tax Act Benefit, Per Share, Diluted Tax Act Benefit, Per Share, Diluted Goodwill and intangible asset impairment Asset Impairment Charges Goodwill and intangible asset impairment (usd per share) Asset Impairment Charge, Per Share, Diluted Asset Impairment Charge, Per Share, Diluted Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Beginning balance Unrecognized Tax Benefits Additions for tax positions related to the current year Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Additions for tax positions related to prior years Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Reductions for tax positions related to prior years Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Reductions for lapse of statute of limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Settlements Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Ending Balance Expiration period Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Intrinsic value of stock options exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Fair value of stock options vested Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value Schedule of Acquired Indefinite-lived Intangible Assets by Major Class [Table] Schedule of Acquired Indefinite-lived Intangible Assets by Major Class [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Customer contracts and relationships Customer Relationships [Member] Trademarks and trade names Trademarks and Trade Names [Member] Contract rights and other Contract Rights And Other [Member] Contract Rights and Other [Member] Acquired Indefinite-lived Intangible Assets [Line Items] Acquired Indefinite-lived Intangible Assets [Line Items] Gross Carrying Amount Finite-Lived Intangible Assets, Gross Accumulated Amortization Total Net impairment charge Impairment of Intangible Assets, Finite-lived Reduction in carrying amount Impairment Of Intangible Assets, Finite-Lived, Gross Impairment Of Intangible Assets, Finite-Lived, Gross Amortization of intangible assets Impairment of Intangible Assets, Finite-lived, Accumulated Amortization Impairment of Intangible Assets, Finite-lived, Accumulated Amortization Intangible assets weighted average life Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Expected life Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Expected stock price volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Stock price (usd per share) Share Price Minimum rental and other Operating Leases, Rent Expense, Minimum Rentals Contingent rental and other Operating Leases, Rent Expense, Contingent Rentals Total Operating Leases, Rent Expense, Net Expense related to service concession arrangements Operating Leases, Rent Expense Deferred tax assets attributable to: Deferred Tax Assets, Net [Abstract] Self-insurance claims (net of recoverables) Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Self Insurance Deferred and other compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits Accounts receivable allowances Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Allowance for Doubtful Accounts Settlement liabilities Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Legal Settlements Other accruals Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Other Other comprehensive income Deferred Tax Assets, Other Comprehensive Loss State taxes Deferred Tax Assets, State Taxes State net operating loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards, State and Local Federal net operating loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards, Domestic Tax credits Deferred Tax Assets, Tax Credit Carryforwards Unrecognized tax benefits Deferred Tax Assets, Unrecognized Tax Benefits Deferred Tax Assets, Unrecognized Tax Benefits Other Deferred Tax Assets, Other Gross deferred tax assets Deferred Tax Assets, Gross Valuation allowance Deferred Tax Assets, Valuation Allowance Total deferred tax assets Deferred Tax Assets, Net of Valuation Allowance Deferred tax liabilities attributable to: Deferred Tax Liabilities, Gross [Abstract] Property, plant and equipment Deferred Tax Liabilities, Property, Plant and Equipment Goodwill and other acquired intangibles Deferred Tax Liabilities, Goodwill and Intangible Assets Other Deferred Tax Liabilities, Other Total deferred tax liabilities Deferred Tax Liabilities, Gross Net deferred tax liabilities Deferred Tax Liabilities, Net Schedule of Future Minimum Lease Payments for Capital Leases Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block] Schedule of Future Minimum Lease Payments for Operating Leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of Rental and Other Expense Schedule of Rent Expense [Table Text Block] Income Taxes [Table] Income Taxes [Table] Income Taxes [Table] Income Tax Authority Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] State and Local Jurisdiction State and Local Jurisdiction [Member] Income Taxes [Line Items] Income Taxes [Line Items] Income Taxes [Line Items] U.S. statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Net discrete tax benefit from remeasurement of deferred taxes at new rate due to Tax Act Tax Cuts and Jobs Act, Measurement Period Adjustment, Income Tax Expense (Benefit) Remeasurement of one-time transition tax on deemed repatriation of indefinitely reinvested earnings Tax Cuts and Jobs Act, Change in Tax Rate, Income Tax Expense (Benefit) Effective tax rate (percent) Effective Income Tax Rate Reconciliation, Percent Income tax provision State true-ups Unrecognized Tax Benefits, Decrease Resulting from State True-Ups Unrecognized Tax Benefits, Decrease Resulting from State True-Ups Federal true-ups Unrecognized Tax Benefits, Decrease Resulting from Federal True-Ups Unrecognized Tax Benefits, Decrease Resulting from Federal True-Ups Work opportunity tax credit, adjustment Increase (Decrease) in Tax Credits, Work Opportunity Tax Credit Increase (Decrease) in Tax Credits, Work Opportunity Tax Credit Tax benefit related to lapse of statute of limitations Tax Benefits Lapse of Statute of Limitations Tax Benefits, Lapse of Statute of Limitations Income tax benefit related to vesting of share-based compensation awards Benefit resulting from research and development credits Unrecognized Tax Benefits, Decrease Resulting from Research and Development Credits Unrecognized Tax Benefits, Decrease Resulting from Research and Development Credits Tax benefits, implementation of tax act Tax Cuts and Jobs Act, Incomplete Accounting, Change in Tax Rate, Provisional Income Tax Expense (Benefit) Income tax benefit related to deduction for energy efficient government buildings Effective Income Tax Reconciliation, Deduction Energy Efficient Government Buildings, Amount Effective Income Tax Reconciliation, Deduction Energy Efficient Government Buildings, Amount Operating loss carryforwards Operating Loss Carryforwards Tax credits Tax Credit Carryforward, Amount Unrecognized tax benefits that would impact effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Maximum decrease in unrecognized tax benefits that is reasonably possible Decrease in Unrecognized Tax Benefits is Reasonably Possible Uncertain tax positions, interest and penalties accrued Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Unrecognized tax benefits, interest and penalties expense Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense Unrecognized tax benefits, interest and penalties benefit Unrecognized Tax Benefits, Interest and Penalties Benefit Unrecognized Tax Benefits, Interest and Penalties Benefit Number of states in which entity operates Number of States in which Entity Operates Restructuring Plan [Axis] Restructuring Plan [Axis] Restructuring Plan [Domain] Restructuring Plan [Domain] GCA Restructuring Program GCA Restructuring Program [Member] GCA Restructuring Program [Member] 2020 Vision Restructuring Program 2020 Vision Restructuring Program [Member] 2020 Vision Restructuring Program [Member] Restructuring and related cost, cumulative cost Restructuring and Related Cost, Cost Incurred to Date Gross profit Gross Profit Income from continuing operations (Loss) income from discontinued operations, net of taxes Net income Income from continuing operations (usd per share) Income from discontinued operations (usd per share) Income from continuing operations (usd per share) Income from discontinued operations (usd per share) Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Common Stock Common Stock [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Accumulated Other Comprehensive Loss, Net of Taxes AOCI Attributable to Parent [Member] Retained Earnings Retained Earnings [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance, beginning of year (in shares) Shares, Outstanding Balance, beginning of year Stock issued under employee stock purchase and share-based compensation plans (in shares) Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture Stock issued (taxes withheld) under employee stock purchase and share-based compensation plans Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture Share-based compensation expense APIC, Share-based Payment Arrangement, Increase for Cost Recognition Stock issued in GCA acquisition, net of shares withheld for taxes (in shares) Stock Issued During Period, Shares, Acquisitions Stock issued in GCA acquisition, net of shares withheld for taxes Stock Issued During Period, Value, Acquisitions Repurchase of common stock (in shares) Repurchase of common stock Other comprehensive (loss) income Other Comprehensive Income (Loss), Net of Tax Dividends Dividends [Abstract] Common stock ($0.720, $0.700, and $0.680 per share) Dividends, Common Stock, Cash Common stock, dividends (usd per share) Common Stock, Dividends, Per Share, Declared Stock issued under share-based compensation plans Dividend, Share-based Payment Arrangement, Shares Cumulative effect adjustment for adoption of Accounting Standards Update 2014-09 Cumulative Effect of New Accounting Principle in Period of Adoption Balance, end of year (in shares) Balance, end of year Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 2006 Equity Plan Two Thousand Six Equity Incentive Plan [Member] Two Thousand Six Equity Incentive Plan [Member] 2004 Employee Stock Purchase Plan Two Thousand Four Employee Stock Purchase Plan [Member] Two Thousand Four Employee Stock Purchase Plan [Member] Number of shares authorized (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Number of shares available for grant (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Fair value percentage of common stock price Share Based Compensation Fair Value Percentage of Common Stock Price Share Based Compensation Fair Value Percentage of Common Stock Price Employee contribution percentage Stock Based Compensation Maximum Employee Contribution Percentage Stock Based Compensation Maximum Employee Contribution Percentage Maximum annual employee contribution Stock Based Compensation Maximum Employee Contribution Stock Based Compensation Maximum Employee Contribution Number of shares unissued (in shares) Common Stock, Capital Shares Reserved for Future Issuance Holding period for shares purchased in program Share-based Compensation Arrangement by Share-based Payment Award, Holding Period On Employee Stock Purchase Share-based Compensation Arrangement by Share-based Payment Award, Holding Period On Employee Stock Purchase Discount rates Securities Discount Rate Over London Interbank Offered Rate The discount rate over London Interbank Offered Rate assumptions used to determine the fair value of auction rate securities. Libor plus stated yield Securities Yields Over London Interbank Offered Rate The fixed yield over London Interbank Offered Rate used as an input in determining the fair value for the one of the Company's auction rate securities. Average expected lives Average Expected Life, Auction Rate Securities The average expected life assumptions used to determine the fair value of auction rate securities. Schedule of Business Acquisitions by Acquisition, Equity Interest Issued or Issuable [Table] Schedule of Business Acquisitions by Acquisition, Equity Interest Issued or Issuable [Table] GCA Holding Corp. GCA Holding Corp. [Member] GCA Holding Corp. [Member] Equity Interest Type [Axis] Equity Interest Type [Axis] Equity Interest Issued or Issuable, Type [Domain] Equity Interest Issued or Issuable, Type [Domain] Business Acquisition, Equity Interests Issued or Issuable [Line Items] Business Acquisition, Equity Interests Issued or Issuable [Line Items] Shares of ABM common stock, net of shares withheld for taxes (in shares) Business Acquisition, Equity Interest Issued or Issuable, Number of Shares ABM common stock closing market price at acquisition date (usd per share) Business Acquisition, Share Price Fair value of ABM common stock at closing Business Combination, Consideration Transferred, Equity Interests Issued and Issuable Cash consideration Payments to Acquire Businesses, Gross Total consideration transferred Schedule of New Accounting Pronouncements Impacts on Balance Sheet and Statements of Comprehensive Income Revenue from External Customers by Major Service Lines and Segments Revenue from External Customers by Products and Services [Table Text Block] Contract with Customer, Asset and Liability Contract with Customer, Asset and Liability [Table Text Block] Acquisitions Business Combination Disclosure [Text Block] The Company and Nature of Operations Nature of Operations [Text Block] Employee Benefit Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Standby letters of credit Letters of Credit Outstanding, Amount Borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Borrowing capacity after covenant restrictions Line of Credit Facility, Remaining Borrowing Capacity After Covenant Restrictions Line of Credit Facility, Remaining Borrowing Capacity After Covenant Restrictions Schedule of Property, Plant and Equipment Property, Plant and Equipment [Table Text Block] Schedule of Capital Leases Included in Property, Plant and Equipment Schedule of Capital Leased Assets [Table Text Block] Statement of Cash Flows [Abstract] Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Loss (income) from discontinued operations, net of taxes Adjustments to reconcile income from continuing operations to net cash provided by operating activities of continuing operations Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Deferred income taxes Deferred Income Tax Expense (Benefit) Share-based compensation expense Share-based Payment Arrangement, Noncash Expense Provision for bad debt Accounts Receivable, Credit Loss Expense (Reversal) Discount accretion on insurance claims Accretion Expense (Gain) loss on sale of assets Gain (Loss) on Disposition of Assets Income from unconsolidated affiliates Distributions from unconsolidated affiliates Proceeds from Equity Method Investment, Distribution Changes in operating assets and liabilities, net of effects of acquisitions Increase (Decrease) in Operating Capital [Abstract] Trade accounts receivable and costs incurred in excess of amounts billed Increase (Decrease) in Receivables Prepaid expenses and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Other noncurrent assets Increase (Decrease) in Other Noncurrent Assets Trade accounts payable and other accrued liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Insurance claims Increase (Decrease) in Self Insurance Reserve Income taxes payable Increase (Decrease) in Income Taxes Payable Other noncurrent liabilities Increase (Decrease) in Other Noncurrent Liabilities Total adjustments Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities Net cash provided by operating activities of continuing operations Net Cash Provided by (Used in) Operating Activities, Continuing Operations Net cash (used in) provided by operating activities of discontinued operations Cash Provided by (Used in) Operating Activities, Discontinued Operations Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Additions to property, plant and equipment Payments to Acquire Property, Plant, and Equipment Proceeds from sale of assets Proceeds from Sale of Other Assets, Investing Activities (Adjustments to) and proceeds from sale of business Divestiture Of Businesses, Adjustments Cash outflow representing an adjustment to a previous divestiture. Purchase of businesses, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Proceeds from redemption of auction rate security Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale Investments in unconsolidated affiliates Payments to Acquire Equity Method Investments Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Taxes withheld from issuance of share-based compensation awards, net (Taxes Withheld) and Proceeds from Issuance of Share Based Compensation Awards (Taxes Withheld) and Proceeds from Issuance of Share Based Compensation Awards Repurchases of common stock Payments for Repurchase of Common Stock Dividends paid Payments of Ordinary Dividends, Common Stock Deferred financing costs paid Payments of Financing Costs Borrowings from credit facility Proceeds from Issuance of Long-term Debt Repayment of borrowings from credit facility Repayments of Long-term Debt Changes in book cash overdrafts Proceeds from (Repayments of) Bank Overdrafts Financing of energy savings performance contracts Proceeds from Construction Loans Payable Repayment of capital lease obligations Repayments of Long-term Capital Lease Obligations Payment of contingent consideration Payment For Contingent Consideration Payment For Contingent Consideration Net cash (used in) provided by financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations Net increase (decrease) in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash and cash equivalents at beginning of year Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash and cash equivalents at end of year Supplemental cash flow information Supplemental Cash Flow Information [Abstract] Income tax payments (refunds), net Income Taxes Paid, Net Interest paid on credit facility Interest Paid, Excluding Capitalized Interest, Operating Activities Non-cash investing and financing activities Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Stock issued in GCA acquisition, net of shares withheld for taxes Schedule of Revenues from External Customers and Long-Lived Assets [Table] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] United States UNITED STATES All other countries Non-US [Member] Revenues Revenues from External Customers and Long-Lived Assets [Line Items] Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Goodwill and Other Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Long-term Debt, Current Maturities [Abstract] Gross term loan Loans Payable, Current, Gross Loans Payable, Current, Gross Unamortized deferred financing costs Debt Issuance Costs, Current, Net Current portion of term loan Long-term Debt, Excluding Current Maturities [Abstract] Gross term loan Loans Payable, Noncurrent, Gross Loans Payable, Noncurrent, Gross Unamortized deferred financing costs Debt Issuance Costs, Noncurrent, Net Total noncurrent portion of term loan Loans Payable, Noncurrent Line of credit Long-term Line of Credit, Noncurrent Long-term debt Schedule of Restructuring and Related Liabilities Restructuring and Related Costs [Table Text Block] Debt instrument, periodic payment, principal Debt Instrument, Periodic Payment, Principal Term Loan Maturities Maturities of Long-term Debt [Abstract] Debt maturities, 2020 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months Debt maturities, 2021 Long-term Debt, Maturities, Repayments of Principal in Year Three Debt maturities, 2022 Long-term Debt, Maturities, Repayments of Principal in Year Two Liability for Claims and Claims Adjustment Expense [Table] Liability for Claims and Claims Adjustment Expense [Table] Insurance Policies [Axis] Insurance Policies [Axis] Insurance Policies [Axis] Insurance Policies [Domain] Insurance Policies [Domain] Insurance Policies [Domain] Insurance claim reserves, excluding medical and dental All Other Claim Types [Member] All Other Claim Types [Member] Medical and dental claim reserves Medical And Dental Self Insurance Program [Member] Medical and Dental Self Insurance Program [Member] Liability for Claims and Claims Adjustment Expense [Line Items] Liability for Claims and Claims Adjustment Expense [Line Items] Insurance claims reserves Self Insurance Reserve Insurance recoverables Reinsurance Recoverable for Unpaid Claims and Claims Adjustments Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Elimination of inter-segment revenues Elimination of inter-segment revenues [Member] Elimination of inter-segment revenues [Member] Corporate Corporate, Non-Segment [Member] Segment Reconciling Items Segment Reconciling Items [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Revenues Segment Reporting Information, Revenue for Reportable Segment [Abstract] Operating profit (loss) Segment Reporting Information, Profit (Loss) [Abstract] Operating profit (loss) Adjustment for tax deductions for energy efficient government buildings, included in Technical Solutions Energy Efficient Government Buildings Tax Credits, Amount Energy Efficient Government Buildings Tax Credits, Amount Depreciation and amortization Depreciation, Depletion and Amortization [Abstract] Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Net balance at beginning of year Liability for Claims and Claims Adjustment Expense Change in case reserves plus IBNR Claims — current year Current Year Claims and Claims Adjustment Expense Change in case reserves plus IBNR Claims — prior years Prior Year Claims and Claims Adjustment Expense Claims paid Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid GCA acquisition Liability for Unpaid Claims and Claims Adjustment Expense, Business Acquisitions Net balance at end of year Recoverables Gross balance at end of year Liability for Claims and Claims Adjustment Expense, Gross Liability for Claims and Claims Adjustment Expense, Gross Provision related to discontinued operations Disposal Group, Including Discontinued Operation, Liability for Unpaid Claims and Claims Adjustment Expense Disposal Group, Including Discontinued Operation, Liability for Unpaid Claims and Claims Adjustment Expense Number of defined contribution plans Number of Defined Contribution Plans Number of Defined Contribution Plans Cost recognized Defined Contribution Plan, Cost Pre-tax increase on retained earnings Cumulative Effect on Retained Earnings, before Tax Schedule of Basic and Diluted Net Income Per Common Share Calculations Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Schedule of Anti-Dilutive Outstanding Stock Awards Issued Under Share-Based Compensation Plans Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Schedule of Deferred Compensation Arrangement with Individual, Postretirement Benefits [Table] Schedule of Deferred Compensation Arrangement with Individual, Postretirement Benefits [Table] Rabbi Trust Rabbi Trust [Member] Rabbi Trust [Member] Other Postretirement Benefits, Individual Contracts, Type of Deferred Compensation [Axis] Other Postretirement Benefits, Individual Contracts, Type of Deferred Compensation [Axis] Other Postretirement Benefits, Individual Contracts, Type of Deferred Compensation [Domain] Other Postretirement Benefits, Individual Contracts, Type of Deferred Compensation [Domain] Deferred Compensation Plans Deferred Compensation Arrangement with Individual, by Type of Compensation, Pension and Other Postretirement Benefits [Member] Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items] Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items] Total liability of deferred compensation Deferred Compensation Liability, Current and Noncurrent Fair value deferred compensation plan assets Compensation expense Deferred Compensation Arrangement with Individual, Compensation Expense Revenues Revenue from Contract with Customer [Text Block] Discontinued Operations and Disposal Groups [Abstract] Discontinued Operations Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Customer relationships Trade names Trade Names [Member] Cash and cash equivalents Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents Trade accounts receivable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables Prepaid expenses and other current assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets Property, plant and equipment Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles Other assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets Trade accounts payable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable Insurance reserves Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Insurance Reserves Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Insurance Reserves Income taxes payable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Income Taxes Payable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Income Taxes Payable Accrued liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other Deferred income tax liability, net Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Other liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other Net assets acquired Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net Acquired Receivables Business Combination, Acquired Receivables [Abstract] Trade accounts receivable, gross Business Combination, Acquired Receivables, Gross Contractual Amount Estimated uncollectible trade accounts receivable Business Combination, Acquired Receivables, Estimated Uncollectible Acquired Intangible Assets Finite-Lived Intangible Assets, Gross [Abstract] Amortization period for acquired intangible assets Schedule of Goodwill [Table] Schedule of Goodwill [Table] Goodwill [Line Items] Goodwill [Line Items] Goodwill impairment (recovery) Goodwill, Impairment Loss Schedule of Compensation Expense by Type of Award and Related Income Tax Benefit Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block] Schedule of RSU Activity Share-based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block] Schedule of Performance Share Activity Schedule of Nonvested Performance-based Units Activity [Table Text Block] Schedule of Monte Carlo Assumptions Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Schedule of Stock Option Activity Share-based Payment Arrangement, Option, Activity [Table Text Block] Schedule of Employee Stock Purchase Plan Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity [Table Text Block] Capital Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] October 31, 2020 Capital Leases, Future Minimum Payments Due, Next Twelve Months October 31, 2021 Capital Leases, Future Minimum Payments Due in Two Years October 31, 2022 Capital Leases, Future Minimum Payments Due in Three Years October 31, 2023 Capital Leases, Future Minimum Payments Due in Four Years October 31, 2024 Capital Leases, Future Minimum Payments Due in Five Years Thereafter Capital Leases, Future Minimum Payments Due Thereafter Total minimum lease commitments Capital Leases, Future Minimum Payments Due Operating and Other Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] October 31, 2020 Operating Leases, Future Minimum Payments Due, Next Twelve Months October 31, 2021 Operating Leases, Future Minimum Payments, Due in Two Years October 31, 2022 Operating Leases, Future Minimum Payments, Due in Three Years October 31, 2023 Operating Leases, Future Minimum Payments, Due in Four Years October 31, 2024 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total minimum lease commitments Operating Leases, Future Minimum Payments Due Estimated future sublease rental income Operating Leases, Future Minimum Payments Receivable Service Concession Arrangements Service Concession Arrangements Leases Minimum Payment Due Absract [Abstract] Service Concession Arrangement Minimum Payment Due Abstract October 31, 2020 Contractual Obligation, Due in Next Fiscal Year October 31, 2021 Contractual Obligation, Due in Second Year October 31, 2022 Contractual Obligation, Due in Third Year October 31, 2023 Contractual Obligation, Due in Fourth Year October 31, 2024 Contractual Obligation, Due in Fifth Year Thereafter Contractual Obligation, Due after Fifth Year Total minimum lease commitments Contractual Obligation Net Income Per Common Share Earnings Per Share [Text Block] Restructuring and Related Costs Restructuring and Related Activities Disclosure [Text Block] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Schedule of Goodwill Activity and Carrying Amount by Segment Schedule of Goodwill [Table Text Block] Schedule of Other Intangible Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Schedule of Estimated Annual Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Schedule of Multiemployer Plans [Table] Schedule of Multiemployer Plans [Table] Building Service 32BJ Pension Fund Building Service Thirty Two B J Pension Fund [Member] Building Service Thirty Two BJ Pension Fund [Member] Central Pension Fund of the IUOE & Participating Employers Central Pension Fund Of The I U O E And Participating Employers [Member] Central Pension Fund Of The IUOE And Participating Employers [Member] S.E.I.U. National Industry Pension Fund S E I U National Industry Pension Fund [Member] SEIU National Industry Pension Fund [Member] SEIU Local 1 & Participating Employers Pension Trust SEIU Local One And Participating Employers Pension Trust [Member] SEIU Local One And Participating Employers Pension Trust [Member] IUOE Stationary Engineers Local 39 Pension Plan I U O E Stationary Engineers Local Thirty Nine Pension Fund [Member] IUOE Stationary Engineers Local Thirty Nine Pension Fund [Member] Local 68 Engineers Union Pension Plan Local Sixty Eight Engineers Union Pension Plan [Member] Local Sixty Eight Engineers Union Pension Plan [Member] Western Conference of Teamsters Pension Plan Western Conference of Teamsters Pension Plan [Member] Western Conference of Teamsters Pension Plan [Member] All Other Plans Other Plans [Member] Other Plans [Member] Multiemployer Plans [Line Items] Multiemployer Plans [Line Items] Multiemployer Plan Number Multiemployer Plan Number Pension Protection Act Zone Status Multiemployer Plans, Certified Zone Status [Fixed List] Pension Protection Act Zone Status, Date Multiemployer Plans, Certified Zone Status, Date FIP/RP Status Pending/Implemented Multiemployer Plans, Funding Improvement Plan and Rehabilitation Plan [Fixed List] Surcharge Imposed Multiemployer Plans, Surcharge [Fixed List] Expiration Dates of Collective Bargaining Agreements, First Multiemployer Plans, Collective-Bargaining Arrangement, Expiration Date, First Expiration Dates of Collective Bargaining Agreements, Last Multiemployer Plans, Collective-Bargaining Arrangement, Expiration Date, Last Red Zone funded percent - Maximum Red Zone Multiemployer Plans Funded Percentage Red Zone Multiemployer Plans Funded Percentage Yellow Zone funded percent - Maximum Yellow Zone Multiemployer Plans Funded Percentage Yellow Zone Multiemployer Plans Funded Percentage Green Zone funded percent - Minimum Green Zone Multiemployer Plan Funded Percentage Green Zone Multiemployer Plan Funded Percentage Schedule of Other Liabilities [Table] Schedule Of Other Liabilities [Table] Schedule of Other Liabilities [Table] Schedule of Other Liabilities [Line Items] Schedule Of Other Liabilities [Line Items] Schedule of Other Liabilities [Line Items] Self insurance retention amount per-claim Self Insured Retention Amount Per Occurrence Self Insured Retention Amount Per Occurrence Primary policy limit Workers Compensation General Liability and Other Insurable Risks Insurance Policy Limit Represents the policy limit provided by the insurance program for workers' compensation, general liability, and other insurable risks. Insurance policy coverage, general and automobile liability losses Insurance Policy Coverage, General Liability And Automobile Liability Losses Represents commercial insurance umbrella policies that cover general liability and automobile liability losses above primary limits. Insurance policy coverage, property damage Property Damage Policy Limit Represents the policy limit provided by the insurance program for property damage risks. Self insurance retention amount per participant per year Self Insured Retention Amount Per Participant Per Year For Certain Employee Medical And Dental Programs Self Insured Retention Amount Per Participant Per Year For Certain Employee Medical And Dental Programs Change in reserves for insurance claims Decrease In Total Reserve Claims Decrease In Total Reserve Claims Change in reserves for insurance claims - prior year Increase in Total Reserve Claims Increase in Total Reserve Claims Basis of Presentation and Significant Accounting Policies Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Cash proceeds on sale of assets Disposal Group, Including Discontinued Operation, Consideration Gain on sale of assets Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax Working capital adjustment to previously recorded gain Disposal Group, Including Discontinued Operation, Working Capital Adjustment Disposal Group, Including Discontinued Operation, Working Capital Adjustment Pretax income (loss) from discontinued operations Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax State and local income taxes, net of federal tax benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Federal and state tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Percent Impact of foreign operations Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent Changes in uncertain tax positions Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Incremental tax benefit from share-based compensation awards Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Payment Arrangement, Percent Tax credits for energy efficient government buildings Effective Income Tax Rate Reconciliation, Deduction, Energy Efficient Government Buildings, Percent Effective Income Tax Rate Reconciliation, Deduction, Energy Efficient Government Buildings, Percent Impact from goodwill impairment Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Percent Transition tax on foreign earnings Effective Income Tax Rate Reconciliation, Tax Cuts And Jobs Act, Transition Tax On Accumulated Foreign Earnings, Percent Effective Income Tax Rate Reconciliation, Tax Cuts And Jobs Act, Transition Tax On Accumulated Foreign Earnings, Percent Remeasurement of U.S. deferred taxes Effective Income Tax Rate Reconciliation, Tax Cuts And Jobs Act, Deferred Tax Remeasurement, Percent Effective Income Tax Rate Reconciliation, Tax Cuts And Jobs Act, Deferred Tax Remeasurement, Percent Nondeductible expenses Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent Other, net Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent Effective tax rate Insurance Insurance Disclosure [Text Block] Leasehold improvements Leasehold Improvements [Member] Land Land [Member] Property, plant and equipment, gross Property, Plant and Equipment, Gross Less: Accumulated depreciation Total Depreciation expense Depreciation Auction Rate Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Management Reimbursement Revenue Management Reimbursement Revenue [Member] Management Reimbursement Revenue [Member] Parking facility management fee revenue Business Acquisition, Pro Forma Information, Nonrecurring Adjustments [Table] Business Acquisition, Pro Forma Information, Nonrecurring Adjustments [Table] Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] Pro forma statutory tax rate (percent) Business Acquisition, Pro Forma Statutory Tax Rate Business Acquisition, Pro Forma Statutory Tax Rate Business combination, acquisition related costs Business Combination, Acquisition Related Costs Pro forma revenue Business Acquisition, Pro Forma Revenue Pro forma income from continuing operations Business Acquisition, Pro Forma Income (Loss) from Continuing Operations, Net of Tax Letters Of Credit [Table] Letters Of Credit [Table] Letters Of Credit [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Surety bonds Surety Bond [Member] Restricted insurance deposits Deposits [Member] Letters Of Credit [Line Items] Letters Of Credit [Line Items] Letters Of Credit [Line Items] Instruments used to collateralize insurance obligations Instruments Used To Collateralize Insurance Obligations Instruments Used To Collateralize Insurance Obligations Healthcare Healthcare Segment [Member] Healthcare Segment [Member] Goodwill [Roll Forward] Goodwill [Roll Forward] Beginning balance Purchase price adjustments Goodwill, Purchase Accounting Adjustments Reallocation Goodwill, Transfers Foreign currency translation Goodwill, Foreign Currency Translation Gain (Loss) Impairment loss Ending balance Percentage of awards originally granted Total unrecognized compensation cost Service period Employee Service Share-based Compensation, TSR Awards, Compensation Cost Not yet Recognized, Period for Recognition Employee Service Share-based Compensation, TSR Awards, Compensation Cost Not yet Recognized, Period for Recognition Loss Contingencies [Table] Loss Contingencies [Table] Litigation Status [Axis] Litigation Status [Axis] Litigation Status [Domain] Litigation Status [Domain] Pending Litigation Pending Litigation [Member] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Energy Savings Contracts Energy Savings Contracts [Member] Energy Savings Contracts [Member] Performance Guarantee Performance Guarantee [Member] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Joint Venture Corporate Joint Venture [Member] Litigation Case [Axis] Litigation Case [Axis] Litigation Case [Domain] Litigation Case [Domain] Castro Castro [Member] Castro [Member] Bucio Bucio [Member] Bucio [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Letters of credit Surety bonds Surety Bonds The amount of bonds, as of the end of the accounting period, issued by a second party, guaranteeing the fulfillment of the Company's obligations to a third party. In the event that the Company does not meet its obligations, the third party will recover its losses via the bond. Guarantee obligation Guarantee Obligation The total amount of guaranteed energy savings. Subsidiary ownership interest percentage Total guarantee Guarantor Obligations, Maximum Exposure, Undiscounted Loss contingency amount accrued for probable losses Loss Contingency Accrual Estimate of reasonably possible loss Loss Contingency, Estimate of Possible Loss Number of certified subclasses Loss Contingency, Number Of Certified Subclasses Loss Contingency, Number Of Certified Subclasses Number of plaintiffs Loss Contingency, Number of Plaintiffs Occurrence period after compliant Loss Contingency, Period Of Occurrence Prior to Compliant Loss Contingency, Period Of Occurrence Prior to Compliant Number of collective bargaining arrangements Loss Contingency, Multiemployer Plans, Collective-Bargaining Arrangement, Number Of Plans Loss Contingency, Multiemployer Plans, Collective-Bargaining Arrangement, Number Of Plans Schedule of Credit Facility Information Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Term Loan Maturities Schedule of Maturities of Long-term Debt [Table Text Block] Schedule of Interest Rate Information Schedule of Interest Rate Derivatives [Table Text Block] Trade accounts receivable, net