Debt Disclosure [Abstract] Revolving Line of Credit Short-term Debt [Text Block] Statement of Cash Flows [Abstract] Statement [Table] Statement [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Statement [Line Items] Statement [Line Items] 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 Compensation Deferred income taxes Deferred Income Tax Expense (Benefit) Tax effect from share-based payment arrangements Tax Benefit From Share-Based Compensation, Operating Activities Tax Benefit From Share-Based Compensation, Operating Activities Excess tax benefits from share-based payment arrangements Excess Tax Benefit from Share-based Compensation, Operating Activities Net amortization of premium on marketable securities Investment Income, Net, Amortization of Discount and Premium Provision for doubtful accounts, net Provision for Doubtful Accounts Net 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 operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations 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 maturities of marketable securities Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities Cash paid for acquisitions, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Distribution from cost method investees Payments for (Proceeds from) Other Investing Activities Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations 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 and other short-term loans Repayments of Short-term Debt Payments on senior notes Repayments of Senior Debt Proceeds from issuance of treasury stock under employee stock plans Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options Dividends paid Payments of Ordinary Dividends, Common Stock Repurchases of common stock Payments for Repurchase of Common Stock Excess tax benefits from share-based payment arrangements Excess Tax Benefit from Share-based Compensation, Financing Activities Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations Effect of exchange rate changes on cash Effect of Exchange Rate on Cash and Cash Equivalents Increase in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents, beginning of period Cash and Cash Equivalents, at Carrying Value 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 Cash paid for interest Interest Paid 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 Unsettled repurchases of common stock Repurchases of Common Stock Incurred Not Yet Paid Repurchases of Common Stock Incurred Not Yet Paid Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Applications Applications [Member] Applications [Member] Scores Scores [Member] Scores [Member] Tools Tools [Member] Tools [Member] Unallocated Corporate Expenses Corporate Segment [Member] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments Operating Segments [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Segment revenues: Segment Reporting Information, Revenue for Reportable Segment [Abstract] Transactional and maintenance Transactional And Maintenance Revenue Transactional-based revenue from credit scoring, data processing, data management and internet delivery services; and revenue from transactional or unit-based license fees under software license arrangements, network service and internally-hosted software agreements recognized based on minimum contractual amounts or on system usage that exceeds minimum contractual amounts. Revenue derived from maintenance services provided under contracts or arrangements with clients. Professional services Technology Services Revenue License Licenses Revenue Total revenues Revenue, Net Segment operating expense Costs and Expenses Unallocated share-based compensation expense Unallocated amortization expense Amortization of Intangible Assets Unallocated restructuring and acquisition-related Restructuring And Acquisition Related Cost Restructuring And Acquisition Related Cost Operating income Operating Income (Loss) Unallocated interest income Investment Income, Interest Unallocated interest expense Interest Expense Unallocated other income (expense), net Other Nonoperating Income (Expense) Income before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest Depreciation expense Depreciation Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Statement of Financial Position [Abstract] Assets Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Accounts receivable, net Accounts Receivable, Net, Current Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Total current assets Assets, Current Marketable securities available for sale Available-for-sale Securities, Noncurrent Other investments Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Property and equipment, net Property, Plant and Equipment, Net Goodwill Goodwill Intangible assets, net Finite-Lived Intangible Assets, Net Deferred income taxes Deferred Tax Assets, Net of Valuation Allowance, Noncurrent Other assets Other Assets, Noncurrent Total assets Assets Liabilities and Stockholders’ Equity Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] 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 Senior notes Senior Notes, Noncurrent 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 32,855 and 34,786 shares outstanding at June 30, 2014 and September 30, 2013, respectively] Common Stock, Value, Outstanding Paid-in-capital Additional Paid in Capital, Common Stock Treasury stock, at cost [56,002 and 54,071 shares at June 30, 2014 and September 30, 2013, 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 Stockholders' Equity Attributable to Parent Total liabilities and stockholders’ equity Liabilities and Equity 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 Canadian Dollar for US Dollar Foreign Exchange Contracts To Sell Canadian Dollar For United States Dollar [Member] Foreign Exchange Contracts to Sell Canadian Dollar for US Dollar [Member] 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] 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 Organization, Consolidation and Presentation of Financial Statements [Abstract] Property, Plant and Equipment Property, Plant and Equipment [Table Text Block] Schedule of Segment Reporting Information, by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Restructuring and Related Activities [Abstract] Restructuring Expenses Restructuring and Related Activities Disclosure [Text Block] Earnings Per Share [Abstract] Options to purchase shares of common stock excluded in the computation of diluted earnings per share because their inclusion would be antidilutive, shares Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Cost of revenues Cost of Sales [Member] Selling, general and administrative expenses Selling, General and Administrative Expenses [Member] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Amortization expense of intangible assets Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Disclosures [Text Block] Schedule of Goodwill [Table] Schedule of Goodwill [Table] Goodwill [Line Items] Goodwill [Line Items] Goodwill [Roll Forward] Goodwill [Roll Forward] Balance at September 30, 2013 Addition from acquisitions Goodwill, Acquired During Period Adjustment related to prior acquisitions Goodwill, Purchase Accounting Adjustments Foreign currency translation adjustment Goodwill, Translation Adjustments Balance at June 30, 2014 Goodwill and Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Statement of Stockholders' Equity [Abstract] Dividends paid, per share Common Stock, Dividends, Per Share, Cash Paid Intangible assets, gross Finite-Lived Intangible Assets, Gross Composition of Certain Financial Statement Captions Supplemental Balance Sheet Disclosures [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] 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] InfoCentricity Inc. Infocentricity Inc [Member] InfoCentricity Inc [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Common stock acquired Business Acquisition, Percentage of Voting Interests Acquired Business acquisition, cash paid Payments to Acquire Businesses, Gross Acquisitions Business Combination Disclosure [Text Block] Income Statement [Abstract] Revenues: Revenue, Net [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 Operating income Interest income Interest expense Other income (expense), net Provision for income taxes Income Tax Expense (Benefit) Net income Other comprehensive income (loss): Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax [Abstract] Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Earnings per share: Basic Earnings Per Share, Basic Diluted Earnings Per Share, Diluted Shares used in computing earnings per share: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Basic Weighted Average Number of Shares Outstanding, Basic Diluted Weighted Average Number of Shares Outstanding, Diluted Line of Credit Facility [Table] Line of Credit Facility [Table] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Libor London Interbank Offered Rate (LIBOR) [Member] Federal Fund Rate Federal Fund Rate [Member] Federal Fund Rate [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Unsecured revolving line of credit Line of Credit Facility, Maximum Borrowing Capacity Revolving credit facility, expiration date Line of Credit Facility, Expiration Date Revolving credit facility, interest rate description Line of Credit Facility, Interest Rate Description Debt instrument basis spread on variable rate Debt Instrument, Basis Spread on Variable Rate Revolving credit facility, utilization fees, percentage of total credit facility commitment to exceed Minimum Credit Facility Utilization Subject To Utilization Fee Percentage of borrowings to total credit facility that if exceeded utilization fees are required to be paid. Credit facility restrictive covenant, maximum consolidated leverage ratio Leverage Ratios Maximum Leverage Ratios Maximum Credit facility restrictive covenant, minimum fixed charge ratio Fixed Charge Coverage Ratio Minimum Fixed Charge Coverage Ratio, Minimum Borrowings outstanding Line of Credit Facility, Amount Outstanding Interest rate of borrowings outstanding Debt, Weighted Average Interest Rate 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 Accounting Policies [Abstract] Fair Isaac Corporation Nature Of Operations Policy [Text Block] Nature of Operations [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 Recently Issued or Adopted New Accounting Pronouncements, Policy [Policy Text Block] Earnings Per Share Earnings Per Share [Text Block] Nature of Business Business Description and Accounting Policies [Text Block] Senior Notes Long-term Debt [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] May 2008 senior notes Senior Notes May Twenty Zero Eight [Member] Senior Notes, May Twenty Zero Eight [Member] July 2010 senior notes Senior Notes July Twenty Ten [Member] Senior Notes, July Twenty Ten [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 Senior Notes, weighted average maturity (in years) Long Term Debt Weighted Average Maturity Long Term Debt, Weighted Average Maturity Carrying value of Senior Notes Senior Notes Fair value of Senior Notes Debt Instrument, Fair Value Disclosure Foreign currency forward contracts Gain (Loss) on Derivative Instruments, Net, Pretax Document And Entity Information [Abstract] Document And Entity Information [Abstract] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding 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] Short-term forward contracts, average maturities at inception Maximum Remaining Maturity of Foreign Currency Derivatives Forward foreign currency contracts fair value Derivative, Fair Value, Net Cash deposits Cash Commitments and Contingencies Disclosure [Abstract] Contingencies Legal Matters and Contingencies [Text Block] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring Fair Value, Measurements, Recurring [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [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 Marketable securities available-for-sale Total Assets, Fair Value Disclosure Schedule of Restructuring and Related Costs Restructuring and Related Costs [Table 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 Effect of dilutive securities Weighted Average Number Diluted Shares Outstanding Adjustment Diluted weighted-average shares Earnings per share: Earnings Per Share, Basic and Diluted [Abstract] Derivative Financial Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Number of reportable segments Number of Reportable Segments Property and equipment Property, Plant and Equipment, Gross Less: accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Total Preferred stock, par value Preferred Stock, Par or Stated Value Per Share Preferred stock, shares authorized Preferred Stock, Shares Authorized Preferred stock, issued Preferred Stock, Shares Issued Preferred stock, outstanding Preferred Stock, Shares Outstanding Common stock, par value 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 Schedule of Notional Amounts of Outstanding Derivative Positions Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance Derivative Instruments, Gain (Loss) [Table Text Block] Estimated future intangible asset amortization expense Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] 2014 [excluding the nine months ended June 30, 2014] Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year 2015 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2016 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2017 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2018 Finite-Lived Intangible Assets, Amortization Expense, Year Five Thereafter Finite-Lived Intangible Assets, Amortization Expense, after Year Five Total Segment Information Segment Reporting Disclosure [Text Block] 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 Accumulated Other Comprehensive Income (Loss) [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning Balance Beginning Balance (in shares) Shares, Outstanding Share-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Issuance of treasury stock under employee stock plans Stock Issued During Period, Value, Employee Stock Purchase Plan Issuance of treasury stock under employee stock plans (in shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Tax effect from share-based payment arrangements Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation Repurchases of common stock Treasury Stock, Value, Acquired, Cost Method Repurchases of common stock (shares) Treasury Stock, Shares, Acquired Dividends paid ($0.06 per share) Dividends, Common Stock, Cash Ending Balance Ending Balance (in shares) Fair Value, Assets Measured on Recurring Basis Fair Value, Assets Measured on Recurring Basis [Table Text Block] 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] Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] September 30, 2013 Restructuring Reserve Expense Additions Restructuring Charges Cash Payments Payments for Restructuring June 30, 2014