Leases [Abstract] Assets Assets [Abstract] Operating leases Operating Lease, Right-of-Use Asset Finance leases Finance Lease, Right-of-Use Asset Total lease assets Lease, Right-of-Use Asset Lease, Right-of-Use Asset Liabilities Liabilities [Abstract] Current: Liabilities, Current [Abstract] Operating leases Operating Lease, Liability, Current Finance leases Finance Lease, Liability, Current Non-current: Liabilities, Noncurrent [Abstract] Operating leases Operating Lease, Liability, Noncurrent Finance leases Finance Lease, Liability, Noncurrent Total lease liabilities Lease, Liability Lease, Liability Finance leases, accumulated depreciation Finance Lease, Right-Of-Use Asset, Accumulated Depreciation Finance Lease, Right-Of-Use Asset, Accumulated Depreciation Debt Disclosure [Abstract] Revolving Line of Credit Short-term Debt [Text Block] Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [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] Completed Technology Technology-Based Intangible Assets [Member] Customer Contracts [Member] Customer-Related Intangible Assets [Member] Trade Names [Member] Trade Names [Member] Noncompete Agreements [Member] Noncompete Agreements [Member] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Amortization expense of intangible assets Amortization of Intangible Assets Carrying Amounts and Fair Values of Senior Notes Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] July 2010 Senior Notes Senior Notes July Twenty Ten [Member] Senior Notes, July Twenty Ten [Member] May 2018 Senior Notes Senior Notes May Twenty Eighteen [Member] Senior Notes May Twenty Eighteen [Member] Senior Notes December Six [Member] Senior Notes December Six [Member] Senior Notes December Six Statistical Measurement [Axis] Statistical Measurement [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Senior Notes issued in a private placement to a group of institutional investors Debt Instrument, Face Amount Number of series of Senior Notes issued Number Of Series Number of Series Senior Notes, maturity (in years) Debt Instrument, Term Senior Notes, weighted average interest rate Debt, Weighted Average Interest Rate Senior Notes, weighted average maturity (in years) Long Term Debt Weighted Average Maturity Long Term Debt, Weighted Average Maturity Net debt to EBITDA ratio maximum Debt Instrument, Covenant, Leverage Ratio, Maximum Debt Instrument, Covenant, Leverage Ratio, Maximum Fixed charge coverage ratio minimum Debt Instrument, Covenant, Fixed Charge Coverage Ratio, Minimum Debt Instrument, Covenant, Fixed Charge Coverage Ratio, Minimum Carrying value of Senior Notes Senior Notes Fair value of Senior Notes Debt Instrument, Fair Value Disclosure Debt issuance costs Debt Issuance Costs, Net Debt instrument, maturity date Debt Instrument, Maturity Date Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Goodwill and Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Net income Net Income (Loss) Attributable to Parent Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Share-based compensation Share-based Payment Arrangement, Noncash Expense Deferred income taxes Deferred Income Tax Expense (Benefit) Net loss on marketable securities Marketable Securities, Unrealized Gain (Loss), Excluding Other-than-temporary Impairment Loss Amortization of Leased Asset Amortization of Leased Asset Provision for doubtful accounts, net Accounts Receivable, Credit Loss Expense (Reversal) Net (gain) loss on sales of property and equipment Gain (Loss) on Disposition of Property Plant Equipment Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Accounts payable Increase (Decrease) in Accounts Payable Accrued compensation and employee benefits Increase (Decrease) in Employee Related Liabilities Other liabilities Increase (Decrease) in Other Operating Liabilities Deferred revenue Increase (Decrease) in Deferred Revenue Net Cash Provided by (Used in) Operating Activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Purchases of property and equipment Payments to Acquire Property, Plant, and Equipment Proceeds from sales of marketable securities Proceeds from Sale and Maturity of Marketable Securities Purchases of marketable securities Payments to Acquire Marketable Securities Distribution from other investments Payments for (Proceeds from) Other Investing Activities Net Cash Provided by (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] Proceeds from revolving line of credit Proceeds from Lines of Credit Payments on revolving line of credit Repayments of Lines of Credit Proceeds from issuance of senior notes Proceeds from Issuance of Senior Long-term Debt Payments on debt issuance costs Payments of Debt Issuance Costs Payment from finance lease Proceeds from (Payments for) Other Financing Activities Proceeds from issuance of treasury stock under employee stock plans Proceeds, Issuance of Shares, Share-based Payment Arrangement, Including Option Exercised Taxes paid related to net share settlement of equity awards Payment, Tax Withholding, Share-based Payment Arrangement Repurchases of common stock Payments for Repurchase of Common Stock Net Cash Provided by (Used in) Financing Activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents 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, beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash and cash equivalents, end of period Supplemental disclosures of cash flow information: Supplemental Cash Flow Information [Abstract] Cash paid for income taxes, net of refunds Income Taxes Paid, Net Interest Paid, Excluding Capitalized Interest, Operating Activities Interest Paid, Excluding Capitalized Interest, Operating Activities Supplemental disclosures of non-cash investing and financing activities: Noncash Investing and Financing Items [Abstract] Purchase of property and equipment included in accounts payable Capital Expenditures Incurred but Not yet Paid Repurchases of Common Stock Incurred Not Yet Paid Repurchases of Common Stock Incurred Not Yet Paid Repurchases of Common Stock Incurred Not Yet Paid Finance lease obligations incurred Lease Obligation Incurred Restructuring and Related Activities [Abstract] Schedule of Restructuring Accruals Restructuring and Related Costs [Table Text Block] Revenue from Contract with Customer [Abstract] Contract With Customer, Liability [Roll Forward] Contract With Customer, Liability [Roll Forward] Contract With Customer, Liability [Roll Forward] Deferred revenues at September 30, 2019 Contract with Customer, Liability Revenue recognized that was included in the deferred revenues balance at the beginning of the period Contract with Customer, Liability, Revenue Recognized Increases due to billings, excluding amounts recognized as revenue during the period Contract With Customer, Liability, Excluding Revenue Recognized Deferred Revenue Increased from Customer Contracts due to cash received Deferred revenues at March 31, 2020 Deferred revenue and other liabilities, current portion Contract with Customer, Liability, Current Deferred revenue and other liabilities, noncurrent Contract with Customer, Liability, Noncurrent Earnings Per Share [Abstract] Earnings per Share Earnings Per Share [Text Block] Segment Reporting [Abstract] Segment Information Segment Reporting Disclosure [Text Block] Contract with Customer, Asset and Liability Contract with Customer, Asset and Liability [Table Text Block] Restructuring and Related Activities Disclosure [Text Block] Restructuring and Related Activities Disclosure [Text Block] Number of operating segments Number of Operating Segments Number of reportable segments Number of Reportable Segments Summary of Segment Information Schedule of Segment Reporting Information, by Segment [Table Text Block] Disaggregation of Revenue [Table Text Block] Disaggregation of Revenue [Table Text Block] Schedule of Goodwill [Table] Schedule of Goodwill [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Applications Applications [Member] Applications [Member] Scores Scores [Member] Scores [Member] Decision Management Software Decision Management Software [Member] Decision Management Software [Member] Goodwill [Line Items] Goodwill [Line Items] Goodwill [Roll Forward] Goodwill [Roll Forward] Balance at September 30, 2019 Goodwill Foreign currency translation adjustment Goodwill, Foreign Currency Translation Gain (Loss) Balance at March 31, 2020 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, amount Revenue, Remaining Performance Obligation, Amount Revenue, remaining performance obligation, expected timing of satisfaction, period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Revenue, Remaining Performance Obligation, Percentage Revenue, Remaining Performance Obligation, Percentage Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative [Table] Derivative [Table] Foreign Exchange Contracts To Purchase Currencies Axis Foreign Exchange Contracts To Purchase Currencies [Axis] Foreign Exchange Contracts To Purchase Currencies Axis Foreign Exchange Contracts To Purchase Currencies Domain Foreign Exchange Contracts To Purchase Currencies [Domain] Foreign Exchange Contracts To Purchase Currencies Domain Foreign Exchange Contracts To Sell European Euro for US Dollar Foreign Exchange Contracts To Sell European Euro For United States Dollar [Member] Foreign Exchange Contracts To Sell European Euro For U S dollar [Member] Foreign Exchange Contracts To Purchase British Pounds With US Dollars Foreign Exchange Contracts To Purchase British Pounds With United States Dollars [Member] Foreign Exchange Contracts To Purchase British Pounds With US Dollars [Member] Foreign Exchange Contracts To Purchase Singapore Dollars With US Dollars Foreign Exchange Contracts To Purchase Singapore Dollars With United States Dollars [Member] [Domain] Foreign Exchange Contracts To Purchase Singapore Dollars With United States Dollars [Member] [Domain] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Foreign currency forward contracts Foreign Exchange Forward [Member] Position [Axis] Position [Axis] Position [Domain] Position [Domain] Short Short [Member] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Derivative [Line Items] Derivative [Line Items] Contract amount of forward foreign currency contracts Derivative Asset, Notional Amount Fair value of forward foreign currency contracts to sell and buy foreign currency Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value Cover [Abstract] Document Type Document Type Document Quarterly Report Document Quarterly 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, Postal Zip Code Entity Address, Postal Zip Code Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province 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 Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Estimated future intangible asset amortization expense Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] 2020 (excluding the six months ended March 31, 2020) Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2023 Finite-Lived Intangible Assets, Amortization Expense, Year Five Total Finite-Lived Intangible Assets, Net Disaggregation of Revenue [Abstract] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Revenue from Contract with Customer Benchmark [Member] Revenue from Contract with Customer Benchmark [Member] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] On-Premises Products [Member] On-Premises Products [Member] On-Premises Products[Member] SaaS Products [Member] SaaS Products [Member] SaaS (Software as a service) Products Scores Products [Member] Scores Products [Member] Scores Products [Member] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] North America [Member] North America [Member] Latin America [Member] Latin America [Member] EMEA [Member] EMEA [Member] Asia Pacific [Member] Asia Pacific [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Revenues Revenue from Contract with Customer, Excluding Assessed Tax Concentration Risk, Percentage Concentration Risk, Percentage New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2016-02 Accounting Standards Update 2016-02 [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Total reported lease liability Operating Lease, Liability Line of Credit Facility [Table] Line of Credit Facility [Table] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Federal Fund Rate Federal Fund Rate [Member] Federal Fund Rate [Member] LIBOR London Interbank Offered Rate (LIBOR) [Member] Base Rate Base Rate [Member] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Unsecured revolving line of credit Line of Credit Facility, Current Borrowing Capacity Revolving credit facility, expiration date Line of Credit Facility, Expiration Date Line of credit facility-option to increase borrowing capacity Line of Credit Facility-Option to Increase Borrowing Capacity Line of Credit Facility-Option to Increase Borrowing Capacity Debt instrument basis spread on variable rate Debt Instrument, Basis Spread on Variable Rate Credit facility restrictive covenant, maximum consolidated leverage ratio Leverage Ratios Maximum Leverage Ratios Maximum Credit facility restrictive covenant, maximum consolidated leverage ratio step up Leverage Ratios, Step Up, Maximum Leverage Ratios, Step Up, Maximum Fixed charge coverage ratio minimum Fixed Charge Coverage Ratio Minimum Fixed Charge Coverage Ratio, Minimum Interest coverage ratio Interest coverage ratio Interest coverage ratio Borrowings outstanding Long-term Line of Credit Interest rate of borrowings outstanding Accounting Policies [Abstract] Nature of Business Business Description and Accounting Policies [Text Block] Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock Common Stock [Member] Paid-in-Capital Additional Paid-in Capital [Member] Treasury Stock Treasury Stock [Member] Retained Earnings Retained Earnings [Member] Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning Balance (in shares) Shares, Outstanding Beginning Balance Stockholders' Equity Attributable to Parent Share-based compensation APIC, Share-based Payment Arrangement, Increase for Cost Recognition Issuance of treasury stock under employee stock plans (in shares) Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture Issuance of treasury stock under employee stock plans Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture Repurchases of common stock (in shares) Treasury Stock, Shares, Acquired Repurchases of common stock Treasury Stock, Value, Acquired, Cost Method Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Ending Balance (in shares) Ending Balance Commitments and Contingencies Disclosure [Abstract] Contingencies Legal Matters and Contingencies [Text Block] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Transactional and Maintenance Transactional and Maintenance [Member] Transactional and Maintenance [Member] Technology Service Technology Service [Member] License License [Member] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments Operating Segments [Member] Unallocated Corporate Expenses Corporate, Non-Segment [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Segment revenues: Segment Reporting Information, Revenue for Reportable Segment [Abstract] Segment operating expense Costs and Expenses Operating income Operating Income (Loss) Unallocated share-based compensation expense Unallocated amortization expense Restructuring And Acquisition Related Cost Restructuring And Acquisition Related Cost Restructuring And Acquisition Related Cost Unallocated interest expense Interest Expense Unallocated other expense, net Other Nonoperating Income (Expense) Income before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Depreciation expense Depreciation Organization, Consolidation and Presentation of Financial Statements [Abstract] Property and equipment Property, Plant, And Equipment And Finance Lease Right-of-Use Asset, Before Accumulated Depreciation And Amortization Property, Plant, And Equipment And Finance Lease Right-of-Use Asset, Before Accumulated Depreciation And Amortization Property and equipment Property, Plant and Equipment, Gross Less: accumulated depreciation and amortization Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization Less: accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Total Property, Plant and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation andAmortization Property, Plant And Equipment And Finance Lease Right-of-Use Asset, After Accumulated Depreciation And Amortization Total Property, Plant and Equipment, Net 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] Facilities charges Facility Closing [Member] Employee separation Employee Severance [Member] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Expense Additions Restructuring Charges Number of positions eliminated Restructuring and Related Cost, Number of Positions Eliminated Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] Accrual at September 30, 2019 Restructuring Reserve Cash Payments Payments for Restructuring Restructuring Reserve, Accrual Adjustment Restructuring Reserve, Accrual Adjustment Accrual at March 31, 2020 Reclassification of accrued lease exit obligations to operating lease liabilities Derivative Financial Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Revenue from External Customers by Products and Services [Table] Revenue from External Customers by Products and Services [Table] Revenue from External Customer [Line Items] Revenue from External Customer [Line Items] Contract With Customer, Payment Term Contract With Customer, Payment Term Contract With Customer, Payment Term Leases Lessee, Operating Leases [Text Block] Leases Lessee, Finance Leases [Text Block] Accounts Receivable, after Allowance for Credit Loss, Noncurrent Accounts Receivable, after Allowance for Credit Loss, Noncurrent Accounts receivable, net Accounts Receivable, after Allowance for Credit Loss, Current Accounts Receivable, before Allowance for Credit Loss Accounts Receivable, before Allowance for Credit Loss Unbilled Receivables, Current Unbilled Receivables, Current Receivables Gross Receivables Gross Receivables, Gross Accounts Receivable, Allowance for Credit Loss Accounts Receivable, Allowance for Credit Loss Accounts Receivable, after Allowance for Credit Loss Accounts Receivable, after Allowance for Credit Loss Income Statement [Abstract] Operating expenses: Costs and Expenses [Abstract] Cost of revenues Cost of Revenue Research and development Research and Development Expense Selling, general and administrative Selling, General and Administrative Expense Amortization of intangible assets Restructuring and acquisition-related Total operating expenses Interest expense, net Other income (expense), net Income tax provision (benefit) Income Tax Expense (Benefit) Net income Other comprehensive gain (loss): Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax [Abstract] Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Earnings per share: Basic (in dollars per share) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Shares used in computing earnings per share: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Statement of Financial Position [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Total current assets Assets, Current Marketable securities Marketable Securities, Noncurrent Other investments Cost Method Investments Property and equipment, net Property and equipment, net Goodwill Intangible assets, net Deferred income tax Deferred Income Tax Assets, Net Other assets Other Assets, Noncurrent Total assets Assets Liabilities and Stockholders’ Equity Liabilities and Equity [Abstract] Current liabilities: Accounts payable Accounts Payable, Current Accrued compensation and employee benefits Employee-related Liabilities, Current Other accrued liabilities Accrued Liabilities, Current Deferred revenue Deferred Revenue, Current Current maturities on debt Debt, Current Total current liabilities Liabilities, Current Long-term debt Long-term Debt Other liabilities Liabilities, Other than Long-term Debt, Noncurrent Total liabilities Liabilities Commitments and contingencies Commitments and Contingencies Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Preferred stock ($0.01 par value; 1,000 shares authorized; none issued and outstanding) Preferred Stock, Value, Outstanding Common stock ($0.01 par value; 200,000 shares authorized, 88,857 shares issued and 29,082 and 28,944 shares outstanding at March 31, 2020 and September 30, 2019, respectively) Common Stock, Value, Outstanding Additional paid-in-capital Additional Paid in Capital, Common Stock Treasury stock, at cost (59,775 and 59,913 shares at March 31, 2020 and September 30, 2019, respectively) Treasury Stock, Value Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total stockholders’ equity Total liabilities and stockholders’ equity Liabilities and Equity Fair Value Disclosures [Abstract] 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] Active Markets for Identical Instruments (Level 1) Fair Value, Inputs, Level 1 [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] Assets: Assets, Fair Value Disclosure [Abstract] Cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Total Assets, Fair Value Disclosure Cash deposits Cash Schedule of Operating & Finance Lease Assets and Liabilities Assets And Liabilities, Lessee [Table Text Block] Assets And Liabilities, Lessee [Table Text Block] Schedule of Lease Expenses, Weighted Average Lease Term and Weighted Average Discount Rates, and Supplemental Cash Flow Information Lease, Cost [Table Text Block] Schedule of Future Lease Payments, Operating Leases Lessee, Operating Lease, Liability, Maturity [Table Text Block] Schedule of Future Lease Payments, Finance Leases Finance Lease, Liability, Maturity [Table Text Block] Schedule of Future Minimum Rental Payments for Operating Leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of Future Minimum Lease Payments for Capital Leases Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block] Operating Leases, After Adoption of 842 Lessee, Operating Lease, Liability, Payment, Due [Abstract] Remainder of fiscal 2020 Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year Fiscal 2021 Lessee, Operating Lease, Liability, Payments, Due Year Two Fiscal 2022 Lessee, Operating Lease, Liability, Payments, Due Year Three Fiscal 2023 Lessee, Operating Lease, Liability, Payments, Due Year Four Fiscal 2024 Lessee, Operating Lease, Liability, Payments, Due Year Five Fiscal 2025 Lessee, Operating Lease, Liability, Payments, Due Year Six Lessee, Operating Lease, Liability, Payments, Due Year Six Thereafter Lessee, Operating Lease, Liability, Payments, Due After Year Six Lessee, Operating Lease, Liability, Payments, Due After Year Six Total future undiscounted lease payments Lessee, Operating Lease, Liability, Payments, Due Less imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Finance Leases, After Adoption of 842 Finance Lease, Liability, Payment, Due [Abstract] Remainder of fiscal 2020 Finance Lease, Liability, Payments, Remainder of Fiscal Year Fiscal 2021 Finance Lease, Liability, Payments, Due Year Two Fiscal 2022 Finance Lease, Liability, Payments, Due Year Three Fiscal 2023 Finance Lease, Liability, Payments, Due Year Four Fiscal 2024 Finance Lease, Liability, Payments, Due Year Five Fiscal 2025 Finance Lease, Liability, Payments, Due Year Six Finance Lease, Liability, Payments, Due Year Six Thereafter Finance Lease, Liability, Payments, Due After Year Six Finance Lease, Liability, Payments, Due After Year Six Total future undiscounted lease payments Finance Lease, Liability, Payment, Due Less imputed interest Finance Lease, Liability, Undiscounted Excess Amount Total reported lease liability Finance Lease, Liability Operating Leases, Before Adoption of 842 Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Fiscal 2020 Operating Leases, Future Minimum Payments Due, Next Twelve Months Fiscal 2021 Operating Leases, Future Minimum Payments, Due in Two Years Fiscal 2022 Operating Leases, Future Minimum Payments, Due in Three Years Fiscal 2023 Operating Leases, Future Minimum Payments, Due in Four Years Fiscal 2024 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total minimum lease payments Operating Leases, Future Minimum Payments Due Capital Leases, Before Adoption of 842 Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Fiscal 2020 Capital Leases, Future Minimum Payments Due, Next Twelve Months Fiscal 2021 Capital Leases, Future Minimum Payments Due in Two Years Fiscal 2022 Capital Leases, Future Minimum Payments Due in Three Years Fiscal 2023 Capital Leases, Future Minimum Payments Due in Four Years Fiscal 2024 Capital Leases, Future Minimum Payments Due in Five Years Thereafter Capital Leases, Future Minimum Payments Due Thereafter Total minimum lease payments Capital Leases, Future Minimum Payments Due Less amount representing interest Capital Leases, Future Minimum Payments, Interest Included in Payments Present value of minimum lease payments Capital Lease Obligations Revenue from Contract with Customer Revenue from Contract with Customer [Text Block] Fair Isaac Corporation Nature Of Operations Policy [Policy Text Block] Nature of Operations, Policy [Policy Text Block] Principles of Consolidation and Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] New Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Contract Balances Revenue from Contract with Customer [Policy Text Block] Leases Lessee, Leases [Policy Text Block] Reconciliation of Numerators and Denominators of Basic and Diluted Earnings Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Operating lease cost Operating Lease, Cost Finance lease cost, depreciation of lease assets Finance Lease, Right-of-Use Asset, Amortization Finance lease cost, interest on lease liabilities Finance Lease, Interest Expense Short-term lease cost Short-term Lease, Cost Variable lease cost Variable Lease, Cost Total lease cost Lease, Cost Operating leases, weighted average remaining lease term (in months) Operating Lease, Weighted Average Remaining Lease Term Operating leases, weighted average discount rate Operating Lease, Weighted Average Discount Rate, Percent Finance leases, weighted average remaining lease term (in months) Finance Lease, Weighted Average Remaining Lease Term Finance leases, weighted average discount rate Finance Lease, Weighted Average Discount Rate, Percent Options to purchase shares of common stock excluded in the computation of diluted earnings per share because their inclusion would be antidilutive (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Unrecognized tax benefits, uncertain tax positions Unrecognized Tax Benefits Unrecognized tax benefits, accrued interest Unrecognized Tax Benefits, Interest on Income Taxes Accrued Summary of Property and Equipment Property, Plant and Equipment [Table Text Block] Schedule of Amortization Expense Finite-lived Intangible Assets Amortization Expense [Table Text Block] Schedule of Finite-Lived Intangible Assets, Future Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Schedule of Goodwill Schedule of Goodwill [Table Text Block] Gains (losses) on foreign currency forward contracts Gain (Loss) on Derivative Instruments, Net, Pretax Lessee Disclosure [Abstract] Cash paid for amounts included in the measurement of lease liabilities: Cash Flow, Lessee [Abstract] Cash Flow, Lessee [Abstract] Operating cash outflow for operating leases Operating Lease, Payments Operating cash outflow for finance leases Finance Lease, Interest Payment on Liability Financing cash outflow for finance leases Finance Lease, Principal Payments Lease assets obtained in exchange for new lease liabilities: Right-Of-Use Asset Obtained In Exchange For Lease Liability [Abstract] Right-Of-Use Asset Obtained In Exchange For Lease Liability [Abstract] Operating leases Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Finance leases Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Composition of Certain Financial Statement Captions Supplemental Balance Sheet Disclosures [Text Block] Preferred stock, par value (in usd per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, shares authorized Preferred Stock, Shares Authorized Preferred stock, shares issued Preferred Stock, Shares Issued Preferred stock, shares outstanding Preferred Stock, Shares Outstanding Common stock, par value (in usd per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized Common Stock, Shares Authorized Common stock, shares issued Common Stock, Shares, Issued Common stock, shares outstanding Common Stock, Shares, Outstanding Treasury stock, shares Treasury Stock, Shares Senior Notes Long-term Debt [Text Block] Numerator for diluted and basic earnings per share: Earnings Per Share Basic And Diluted Numerator [Abstract] Earnings Per Share Basic And Diluted Numerator [Abstract] Denominator - share: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic weighted-average shares (in shares) Effect of dilutive securities (in shares) Weighted Average Number Diluted Shares Outstanding Adjustment Diluted weighted-average shares (in shares) Earnings per share: Earnings Per Share, Basic and Diluted [Abstract] Fair Value Measurements Fair Value Disclosures [Text Block] Short-term forward contracts, average maturities at inception (less than) Maximum Remaining Maturity of Foreign Currency Derivatives Forward foreign currency contracts fair value Derivative, Fair Value, Net Financial Assets Measured on a Recurring Basis Fair Value, Assets Measured on Recurring Basis [Table Text Block] Summary of Outstanding Foreign Currency Forward Contracts Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Losses on Derivative Financial Instruments Derivative Instruments, Gain (Loss) [Table Text Block]