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Schedule of Servicing Assets at Fair Value [Table Text Block] 60 – 89 calendar days past due Financial Asset, 60 to 89 Days Past Due [Member] Vested and exercisable (in USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Common stock, dividends declared (in USD per share) Common Stock, Dividends, Per Share, Cash Paid, Threshold For Additional Temporary Equity Dividends Common Stock, Dividends, Per Share, Cash Paid, Threshold For Additional Temporary Equity Dividends 2021-A Affirm Asset Securitization Trust 2021-A Notes [Member] Affirm Asset Securitization Trust 2021-A Notes Percentage of residual certificates retained Securitized Assets, Percentage Of Residual Certificates Retained Securitized Assets, Percentage Of Residual Certificates Retained Net Loss per Share Attributable to Common Stockholders Earnings Per Share [Text Block] Other Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent U.S. statutory federal income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Shares withheld for tax withholding requirements (in shares) Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation 2021-A Notes, Class B Affirm Asset Securitization Trust 2021-A Notes, Class B [Member] Affirm Asset Securitization Trust 2021-A Notes, Class B Recently Adopted Accounting Standards and Recent Accounting Pronouncements Not Yet Adopted New Accounting Pronouncements, Policy [Policy Text Block] Discount rate Measurement Input, Discount Rate [Member] Statement of Financial Position [Abstract] Program profitability Measurement Input, Program Profitability [Member] Measurement Input, Program Profitability