| Line Item | Jun 30, 2026 | Mar 31, 2026 | Dec 31, 2025 | Sep 30, 2025 | Jun 30, 2025 | Mar 31, 2025 | Dec 31, 2024 | Sep 30, 2024 | Jun 30, 2024 | Mar 31, 2024 |
|---|---|---|---|---|---|---|---|---|---|---|
| Revenue | ||||||||||
| Operating expenses | ||||||||||
| Research and development | ||||||||||
| General and administrative | ||||||||||
| Loss from operations | ||||||||||
| Foreign exchange gain, net | ||||||||||
| Interest income | ||||||||||
| Other income, net | ||||||||||
| Loss before income tax | ||||||||||
| Income tax expenses | ||||||||||
| Net loss from continuing operations | ||||||||||
| Net loss | ||||||||||
| Less: Net loss attributable to noncontrolling interests from continuing operations | ||||||||||
| Less: Net loss attributable to noncontrolling interests from discontinued operations | ||||||||||
| Net income (loss) attributable to BeyondSpring Inc. | ||||||||||
| Basic and diluted earnings (loss) per share (in dollars per share) |