| Segment Reporting, Reconciliation of Revenue by Segment to Consolidated [Table Text Block] |
| | | Three Months Ended September 30, | | | Nine Months Ended September 30, | |
| (in thousands) | | 2026 | | | 2025 | | | 2026 | | | 2025 | |
| Segment revenue from external customers | | $ | 56 | | | $ | 15 | | | $ | 161 | | | $ | 123 | |
| Segment operating expenses: | | | | | | | | | | | | | | | | |
| Cost of revenue | | | 16 | | | | — | | | | 52 | | | | 20 | |
| Research and development: | | | | | | | | | | | | | | | | |
| CNM-Au8: | | | | | | | | | | | | | | | | |
| Amyotrophic lateral sclerosis | | | 1,509 | | | | 1,775 | | | | 3,045 | | | | 4,586 | |
| Multiple sclerosis | | | 45 | | | | 41 | | | | 152 | | | | 230 | |
| Regulatory activities | | | 483 | | | | 75 | | | | 1,050 | | | | 335 | |
| General/preclinical/nonclinical | | | 17 | | | | (108 | ) | | | 138 | | | | (26 | ) |
| Facilities | | | 423 | | | | 436 | | | | 1,207 | | | | 1,241 | |
| Depreciation | | | 333 | | | | 337 | | | | 1,007 | | | | 1,012 | |
| Manufacturing | | | 776 | | | | 363 | | | | 931 | | | | 633 | |
| Research | | | 3 | | | | 1 | | | | 13 | | | | 8 | |
| Equipment | | | 40 | | | | 30 | | | | 124 | | | | 58 | |
| Maintenance | | | 69 | | | | 53 | | | | 118 | | | | 117 | |
| Information technology | | | 102 | | | | 68 | | | | 245 | | | | 187 | |
| Personnel | | | 2,201 | | | | 1,945 | | | | 6,412 | | | | 6,205 | |
| Stock-based compensation | | | 524 | | | | 754 | | | | 1,764 | | | | 2,300 | |
| Grant revenue as a reduction of research and development expense | | | (2,107 | ) | | | (2,270 | ) | | | (8,021 | ) | | | (8,495 | ) |
| Other segment items ‒ Research and development(1) | | | 29 | | | | 13 | | | | 62 | | | | 117 | |
| General and administrative: | | | | | | | | | | | | | | | | |
| Insurance | | | 158 | | | | 182 | | | | 486 | | | | 544 | |
| Legal | | | 37 | | | | 70 | | | | 232 | | | | 393 | |
| Finance and accounting | | | 226 | | | | 270 | | | | 714 | | | | 800 | |
| Public and investor relations | | | 80 | | | | 63 | | | | 282 | | | | 293 | |
| Facilities | | | 31 | | | | 29 | | | | 94 | | | | 90 | |
| Depreciation | | | 16 | | | | 28 | | | | 50 | | | | 123 | |
| Information technology | | | 38 | | | | 27 | | | | 100 | | | | 123 | |
| Personnel | | | 837 | | | | 569 | | | | 2,254 | | | | 2,189 | |
| Stock-based compensation | | | 555 | | | | 949 | | | | 1,667 | | | | 2,717 | |
| Grant revenue as a reduction of general and administrative expense | | | (116 | ) | | | (130 | ) | | | (445 | ) | | | (358 | ) |
| Other segment items ‒ General and administrative(2) | | | 78 | | | | 93 | | | | 183 | | | | 269 | |
| Segment loss from operations | | | (6,347 | ) | | | (5,648 | ) | | | (13,755 | ) | | | (15,588 | ) |
| | | | | | | | | | | | | | | | | |
| Reconciliation of segment loss from operations: | | | | | | | | | | | | | | | | |
| Adjustments and reconciling items | | | — | | | | — | | | | — | | | | — | |
| Consolidated loss from operations | | $ | (6,347 | ) | | $ | (5,648 | ) | | $ | (13,755 | ) | | $ | (15,588 | ) |
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| Segment Reporting, Reconciliation of Profit (Loss) by Segment to Consolidated [Table Text Block] |
| | | Three Months Ended September 30, | | | Nine Months Ended September 30, | |
| (in thousands) | | 2026 | | | 2025 | | | 2026 | | | 2025 | |
| Segment loss from operations | | $ | (6,347 | ) | | $ | (5,648 | ) | | $ | (13,755 | ) | | $ | (15,588 | ) |
| Total other income (expense), net(1) | | | 10,262 | | | | (3,129 | ) | | | (3,845 | ) | | | (1,359 | ) |
| Net income (loss) before income taxes | | $ | 3,915 | | | $ | (8,777 | ) | | $ | (17,600 | ) | | $ | (16,947 | ) |
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