{"cik":100826,"taxonomy":"us-gaap","tag":"ContractWithCustomerLiabilityCurrent","label":"Contract with Customer, Liability, Current","description":"Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.","entityName":"Ameren Corporation","units":{"USD":[{"end":"2025-12-31","val":238000000,"accn":"0001002910-26-000032","fy":2026,"fp":"Q3","form":"10-Q","filed":"2026-11-06","frame":"CY2025Q4I"},{"end":"2026-09-30","val":244000000,"accn":"0001002910-26-000032","fy":2026,"fp":"Q3","form":"10-Q","filed":"2026-11-06","frame":"CY2026Q3I"}]}}