| In millions, except per share items | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 | Dec-31-13 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net product revenues | 42.2 | 4.3 | 2.0 | | | | | |
| Net product revenues growth | 890.7% | 116.5% | | | | | | -100.0% |
| Operating costs and expenses: | | | | | | | | |
| Cost of product revenues | 4.6 | 0.6 | 0.3 | | | | | |
| Research and development | 31.3 | 28.3 | 26.4 | 17.7 | 13.9 | 19.4 | 18.7 | 3.1 |
| Selling, general and administrative | 22.0 | 37.9 | 26.5 | 14.0 | 8.3 | 7.9 | 8.5 | 1.1 |
| Restructuring costs | 4.2 | | | | 0.7 | | | |
| Total operating costs and expenses | 62.1 | 66.8 | 53.2 | 31.7 | 22.8 | 27.3 | 27.2 | 4.2 |
| Income (loss) from operations | -20.0 | -62.6 | -51.3 | -31.7 | -22.8 | -27.3 | -27.2 | -4.2 |
| Operating margin | -47.4% | -1470.1% | -2607.1% | | | | | |
| Interest and other expense, net | -1.8 | 1.2 | 1.6 | | | | | |
| Net income (loss) | -21.8 | -61.4 | -49.7 | -30.9 | -22.5 | -27.1 | -27.1 | -4.2 |
| Change in unrealized gains or losses on available-for-sale securities | 0.0 | 0.0 | 0.0 | | | | | |
| Comprehensive income (loss) | -21.8 | -61.4 | -49.7 | -30.9 | -22.5 | -27.2 | -27.2 | -4.2 |
| |
| Net income (loss) per share, basic (in dollars per share) | ($0.55) | ($1.59) | ($1.60) | ($1.23) | ($1.13) | ($1.37) | ($1.44) | ($1.13) |
| |
| Weighted-average number of common shares outstanding, basic (in shares) | 39.3 | 38.7 | 31.0 | 25.1 | 19.9 | 19.8 | 18.8 | 3.7 |
| Net income (loss) per share, diluted (in dollars per share) | ($0.55) | ($1.59) | ($1.60) | ($1.23) | ($1.13) | ($1.37) | ($1.44) | ($1.13) |
| Weighted-average number of common shares outstanding, diltued (in shares) | 39.3 | 38.7 | 31.0 | | | | | |