{"cik":1501697,"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":"X4 PHARMACEUTICALS, INC","units":{"USD":[{"end":"2018-12-31","val":9738000,"accn":"0001564590-19-007097","fy":2018,"fp":"FY","form":"10-K","filed":"2019-03-11"},{"end":"2018-12-31","val":10000000,"accn":"0001193125-19-148119","fy":2019,"fp":"Q1","form":"10-Q","filed":"2019-05-15"},{"end":"2018-12-31","val":10000000,"accn":"0001564590-19-029551","fy":2019,"fp":"Q2","form":"10-Q","filed":"2019-08-07"},{"end":"2018-12-31","val":10000000,"accn":"0001628280-19-013715","fy":2019,"fp":"Q3","form":"10-Q","filed":"2019-11-07"},{"end":"2018-12-31","val":10000000,"accn":"0001628280-20-003484","fy":2019,"fp":"FY","form":"10-K","filed":"2020-03-12","frame":"CY2018Q4I"},{"end":"2019-03-31","val":19546000,"accn":"0001193125-19-148119","fy":2019,"fp":"Q1","form":"10-Q","filed":"2019-05-15","frame":"CY2019Q1I"},{"end":"2019-06-30","val":26717000,"accn":"0001564590-19-029551","fy":2019,"fp":"Q2","form":"10-Q","filed":"2019-08-07","frame":"CY2019Q2I"},{"end":"2019-09-30","val":20000000,"accn":"0001628280-19-013715","fy":2019,"fp":"Q3","form":"10-Q","filed":"2019-11-07","frame":"CY2019Q3I"},{"end":"2019-12-31","val":20000000,"accn":"0001628280-20-003484","fy":2019,"fp":"FY","form":"10-K","filed":"2020-03-12"},{"end":"2019-12-31","val":20000000,"accn":"0001628280-20-006998","fy":2020,"fp":"Q1","form":"10-Q","filed":"2020-05-07"},{"end":"2019-12-31","val":20000000,"accn":"0001628280-20-011644","fy":2020,"fp":"Q2","form":"10-Q","filed":"2020-08-04"},{"end":"2019-12-31","val":20000000,"accn":"0001628280-20-015792","fy":2020,"fp":"Q3","form":"10-Q","filed":"2020-11-05"},{"end":"2019-12-31","val":20000000,"accn":"0001628280-21-005202","fy":2020,"fp":"FY","form":"10-K","filed":"2021-03-19","frame":"CY2019Q4I"},{"end":"2020-03-31","val":25000000,"accn":"0001628280-20-006998","fy":2020,"fp":"Q1","form":"10-Q","filed":"2020-05-07","frame":"CY2020Q1I"},{"end":"2020-06-30","val":25000000,"accn":"0001628280-20-011644","fy":2020,"fp":"Q2","form":"10-Q","filed":"2020-08-04","frame":"CY2020Q2I"},{"end":"2020-09-30","val":25000000,"accn":"0001628280-20-015792","fy":2020,"fp":"Q3","form":"10-Q","filed":"2020-11-05","frame":"CY2020Q3I"},{"end":"2020-12-31","val":32500000,"accn":"0001628280-21-005202","fy":2020,"fp":"FY","form":"10-K","filed":"2021-03-19"},{"end":"2020-12-31","val":32500000,"accn":"0001628280-21-009166","fy":2021,"fp":"Q1","form":"10-Q","filed":"2021-05-06"},{"end":"2020-12-31","val":32500000,"accn":"0001628280-21-015330","fy":2021,"fp":"Q2","form":"10-Q","filed":"2021-08-03"},{"end":"2020-12-31","val":32500000,"accn":"0001628280-21-021795","fy":2021,"fp":"Q3","form":"10-Q","filed":"2021-11-04"},{"end":"2020-12-31","val":32500000,"accn":"0001628280-22-006547","fy":2021,"fp":"FY","form":"10-K","filed":"2022-03-17","frame":"CY2020Q4I"},{"end":"2021-03-31","val":32500000,"accn":"0001628280-21-009166","fy":2021,"fp":"Q1","form":"10-Q","filed":"2021-05-06","frame":"CY2021Q1I"},{"end":"2021-06-30","val":32500000,"accn":"0001628280-21-015330","fy":2021,"fp":"Q2","form":"10-Q","filed":"2021-08-03","frame":"CY2021Q2I"},{"end":"2021-09-30","val":32500000,"accn":"0001628280-21-021795","fy":2021,"fp":"Q3","form":"10-Q","filed":"2021-11-04","frame":"CY2021Q3I"},{"end":"2021-12-31","val":32500000,"accn":"0001628280-22-006547","fy":2021,"fp":"FY","form":"10-K","filed":"2022-03-17"},{"end":"2021-12-31","val":32500000,"accn":"0001628280-22-014095","fy":2022,"fp":"Q1","form":"10-Q","filed":"2022-05-12"},{"end":"2021-12-31","val":32500000,"accn":"0001628280-22-021070","fy":2022,"fp":"Q2","form":"10-Q","filed":"2022-08-04"},{"end":"2021-12-31","val":32500000,"accn":"0001628280-22-028201","fy":2022,"fp":"Q3","form":"10-Q","filed":"2022-11-03"},{"end":"2021-12-31","val":32500000,"accn":"0001628280-23-008745","fy":2022,"fp":"FY","form":"10-K","filed":"2023-03-21","frame":"CY2021Q4I"},{"end":"2022-03-31","val":32500000,"accn":"0001628280-22-014095","fy":2022,"fp":"Q1","form":"10-Q","filed":"2022-05-12","frame":"CY2022Q1I"},{"end":"2022-06-30","val":32500000,"accn":"0001628280-22-021070","fy":2022,"fp":"Q2","form":"10-Q","filed":"2022-08-04","frame":"CY2022Q2I"},{"end":"2022-09-30","val":32500000,"accn":"0001628280-22-028201","fy":2022,"fp":"Q3","form":"10-Q","filed":"2022-11-03","frame":"CY2022Q3I"},{"end":"2022-12-31","val":32500000,"accn":"0001628280-23-008745","fy":2022,"fp":"FY","form":"10-K","filed":"2023-03-21"},{"end":"2022-12-31","val":32500000,"accn":"0001628280-23-015763","fy":2022,"fp":"Q3","form":"10-Q","filed":"2023-05-04"},{"end":"2022-12-31","val":32500000,"accn":"0001628280-23-028897","fy":2023,"fp":"Q3","form":"10-Q","filed":"2023-08-10"},{"end":"2022-12-31","val":32500000,"accn":"0001628280-23-038334","fy":2023,"fp":"Q3","form":"10-Q","filed":"2023-11-09"},{"end":"2022-12-31","val":32500000,"accn":"0001628280-24-012578","fy":2023,"fp":"FY","form":"10-K","filed":"2024-03-21","frame":"CY2022Q4I"},{"end":"2023-03-31","val":32500000,"accn":"0001628280-23-015763","fy":2022,"fp":"Q3","form":"10-Q","filed":"2023-05-04","frame":"CY2023Q1I"},{"end":"2023-06-30","val":32500000,"accn":"0001628280-23-028897","fy":2023,"fp":"Q3","form":"10-Q","filed":"2023-08-10","frame":"CY2023Q2I"},{"end":"2023-09-30","val":55000000,"accn":"0001628280-23-038334","fy":2023,"fp":"Q3","form":"10-Q","filed":"2023-11-09","frame":"CY2023Q3I"},{"end":"2023-12-31","val":55000000,"accn":"0001628280-24-012578","fy":2023,"fp":"FY","form":"10-K","filed":"2024-03-21"},{"end":"2023-12-31","val":55000000,"accn":"0001628280-24-021120","fy":2024,"fp":"Q1","form":"10-Q","filed":"2024-05-07"},{"end":"2023-12-31","val":55000000,"accn":"0001628280-24-036127","fy":2024,"fp":"Q2","form":"10-Q","filed":"2024-08-08"},{"end":"2023-12-31","val":55000000,"accn":"0001628280-24-047445","fy":2024,"fp":"Q3","form":"10-Q","filed":"2024-11-13"},{"end":"2023-12-31","val":55000000,"accn":"0001628280-25-014805","fy":2024,"fp":"FY","form":"10-K","filed":"2025-03-26","frame":"CY2023Q4I"},{"end":"2024-03-31","val":55000000,"accn":"0001628280-24-021120","fy":2024,"fp":"Q1","form":"10-Q","filed":"2024-05-07","frame":"CY2024Q1I"},{"end":"2024-06-30","val":75000000,"accn":"0001628280-24-036127","fy":2024,"fp":"Q2","form":"10-Q","filed":"2024-08-08","frame":"CY2024Q2I"},{"end":"2024-09-30","val":75000000,"accn":"0001628280-24-047445","fy":2024,"fp":"Q3","form":"10-Q","filed":"2024-11-13","frame":"CY2024Q3I"},{"end":"2024-12-31","val":75000000,"accn":"0001628280-25-014805","fy":2024,"fp":"FY","form":"10-K","filed":"2025-03-26"},{"end":"2024-12-31","val":75000000,"accn":"0001628280-25-021358","fy":2025,"fp":"Q1","form":"10-Q","filed":"2025-05-01"},{"end":"2024-12-31","val":75000000,"accn":"0001628280-25-039327","fy":2025,"fp":"Q2","form":"10-Q","filed":"2025-08-08"},{"end":"2024-12-31","val":75000000,"accn":"0001501697-25-000043","fy":2025,"fp":"Q3","form":"10-Q","filed":"2025-11-05"},{"end":"2024-12-31","val":75000000,"accn":"0001501697-26-000018","fy":2025,"fp":"FY","form":"10-K","filed":"2026-03-17","frame":"CY2024Q4I"},{"end":"2025-03-31","val":75000000,"accn":"0001628280-25-021358","fy":2025,"fp":"Q1","form":"10-Q","filed":"2025-05-01","frame":"CY2025Q1I"},{"end":"2025-06-30","val":75000000,"accn":"0001628280-25-039327","fy":2025,"fp":"Q2","form":"10-Q","filed":"2025-08-08","frame":"CY2025Q2I"},{"end":"2025-09-30","val":75000000,"accn":"0001501697-25-000043","fy":2025,"fp":"Q3","form":"10-Q","filed":"2025-11-05","frame":"CY2025Q3I"},{"end":"2025-12-31","val":75000000,"accn":"0001501697-26-000018","fy":2025,"fp":"FY","form":"10-K","filed":"2026-03-17"},{"end":"2025-12-31","val":75000000,"accn":"0001501697-26-000040","fy":2026,"fp":"Q1","form":"10-Q","filed":"2026-05-06"},{"end":"2025-12-31","val":75000000,"accn":"0001501697-26-000068","fy":2026,"fp":"Q2","form":"10-Q","filed":"2026-08-06","frame":"CY2025Q4I"},{"end":"2026-03-31","val":75000000,"accn":"0001501697-26-000040","fy":2026,"fp":"Q1","form":"10-Q","filed":"2026-05-06","frame":"CY2026Q1I"},{"end":"2026-06-30","val":75000000,"accn":"0001501697-26-000068","fy":2026,"fp":"Q2","form":"10-Q","filed":"2026-08-06","frame":"CY2026Q2I"}]}}