{"cik":1653087,"taxonomy":"us-gaap","tag":"LongTermDebt","label":"Long-term Debt","description":"Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.","entityName":"Alector, Inc.","units":{"USD":[{"end":"2024-12-31","val":10000000,"accn":"0000950170-25-027758","fy":2024,"fp":"FY","form":"10-K","filed":"2025-02-26","frame":"CY2024Q4I"},{"end":"2025-12-31","val":10000000,"accn":"0001193125-26-071593","fy":2025,"fp":"FY","form":"10-K","filed":"2026-02-25","frame":"CY2025Q4I"}]}}