Nature of Business	3 Months Ended
Nature of Business	Dec. 31, 2019
Accounting Policies [Abstract]
Nature of Business	Nature of Business Fair Isaac Corporation Incorporated under the laws of the State of Delaware, Fair Isaac Corporation (“FICO”) is a provider of analytic, software and data management products and services that enable businesses to automate, improve and connect decisions. FICO provides a range of analytical solutions, credit scoring and credit account management products and services to banks, credit reporting agencies, credit card processing agencies, insurers, retailers, telecommunications providers, pharmaceutical companies, healthcare organizations, public agencies and organizations in other industries. In this Quarterly Report on Form 10-Q, Fair Isaac Corporation is referred to as “FICO,” “we,” “us,” “our,” or “the Company.” Principles of Consolidation and Basis of Presentation We have prepared the accompanying unaudited interim condensed consolidated financial statements in accordance with the instructions to Form 10-Q and the applicable accounting guidance. Consequently, we have not necessarily included all information and footnotes required for audited financial statements. In our opinion, the accompanying unaudited interim condensed consolidated financial statements reflect all adjustments (consisting only of normal recurring adjustments, except as otherwise indicated) necessary for a fair presentation of our financial position and results of operations. These unaudited condensed consolidated financial statements and notes thereto should be read in conjunction with our audited consolidated financial statements and notes thereto presented in our Annual Report on Form 10-K for the fiscal year ended September 30, 2019. The interim financial information contained in this report is not necessarily indicative of the results to be expected for any other interim period or for the entire fiscal year. As discussed in New Accounting Pronouncements below and Note 14, effective October 1, 2019, we adopted Accounting Standards Update (“ASU”) No. 2016-02, “Leases (Topic 842)” and subsequent amendments to the initial guidance: ASU 2017-13, ASU 2018-10, ASU 2018-11, ASU 2018-20 and ASU 2019-01 (collectively, “Topic 842”) using the modified retrospective approach, under which financial results reported in prior periods were not restated. As a result, the condensed consolidated balance sheet as of December 31, 2019 is not comparable with that as of September 30, 2019. See our Annual Report on Form 10-K filed with the SEC on November 8, 2019 for lease policies that were in effect in prior periods before adoption of Topic 842. The condensed consolidated financial statements include the accounts of FICO and its subsidiaries. All intercompany accounts and transactions have been eliminated. Use of Estimates We make estimates and assumptions that affect the amounts reported in the financial statements and the disclosures made in the accompanying notes. For example, we use estimates in determining the collectability of accounts receivable; the appropriate levels of various accruals; labor hours in connection with fixed-fee service contracts; the amount of our tax provision and the realizability of deferred tax assets. We also use estimates in determining the remaining economic lives and carrying values of acquired intangible assets, property and equipment, and other long-lived assets. In addition, we use assumptions to estimate the fair value of reporting units and share-based compensation. Actual results may differ from our estimates. New Accounting Pronouncements Recently Adopted Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued Topic 842, which requires the recognition of operating lease assets and lease liabilities on the balance sheet. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. Under the new standard, disclosures are required to enable users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. In the first quarter of fiscal 2020, we adopted Topic 842 using the “Comparatives Under 840 Option” approach to transition. In accordance with the standard, the comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. Topic 842 provided a package of practical expedients that allow an entity to not reassess (1) whether any expired or existing contracts contain a lease, (2) the lease classification of any expired or existing lease, and (3) initial direct costs for any existing leases. We elected to apply the package of practical expedients, and did not elect the hindsight practical expedient in determining the lease term for existing leases as of October 1, 2019. Adoption of Topic 842 did not result in the recognition of a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The most significant impact of adoption was the recognition of operating lease assets and operating lease liabilities of $89.8 million and $98.9 million, respectively, while our accounting for existing capital leases (now referred to as finance leases) remained substantially unchanged. We expect the impact of adoption to be immaterial to our consolidated statements of income and comprehensive income and consolidated statements of cash flows on an ongoing basis. As part of our adoption, we also modified our control procedures and processes, none of which materially affected our internal control over financial reporting. See Note 14 for additional information regarding our accounting policy for leases and additional disclosures. Recent Accounting Pronouncements Not Yet Adopted In August 2018, the FASB issued ASU No. 2018-15, “Intangibles—Goodwill and Other (Topic 350): Internal-Use Software.” ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a cloud computing arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The standard is effective for fiscal years and interim periods within those fiscal years beginning after December 15, 2019, which means that it will be effective for our fiscal year beginning October 1, 2020. Early adoption is permitted. We are currently evaluating the impact of our pending adoption of ASU 2018-15 on our consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” and subsequent amendments to the initial guidance: ASU 2018-19, ASU 2019-04, ASU 2019-05 and ASU 2019-11 (collectively, “Topic 326”). Topic 326 requires measurement and recognition of expected credit losses for financial assets held. Topic 326 is effective for fiscal years and interim periods within those fiscal years beginning after December 15, 2019, which means it will be effective for our fiscal year beginning October 1, 2020. Early adoption is permitted. We are currently evaluating the impact of our pending adoption of Topic 326 on our consolidated financial statements. We do not expect that any other recently issued accounting pronouncements will have a significant effect on our financial statements.