| In millions, except per share items | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Operating activities | | | | | | | | |
| Net loss | -53.3 | -35.6 | 9.4 | -5.3 | -65.0 | -26.9 | | |
| |
| Adjustments to reconcile net loss to net cash used in operating activities: | | | | | | | | |
| Depreciation and amortization | 0.1 | 0.0 | | | | 0.0 | 9.6 | 6.2 |
| Stock-based compensation | 5.1 | 2.4 | 2.4 | 2.5 | 1.1 | 1.0 | 1.1 | 2.8 |
| Non-cash interest expense | 1.0 | 0.5 | 0.6 | 0.6 | 0.5 | 0.5 | 0.7 | 0.3 |
| Non-cash change in fair value of PIPE Warrant liability | -0.2 | -4.9 | -11.6 | -19.9 | 33.7 | -4.8 | | |
| Amortization of premium and discount on investments | 0.1 | -0.1 | 0.0 | 0.0 | 0.1 | 0.0 | 0.0 | 0.2 |
| Changes in operating assets and liabilities: | | | | | | | | |
| Trade receivables, net | -9.8 | | | -2.6 | 0.6 | 3.6 | -2.3 | -1.4 |
| Partnership receivables | -0.6 | 0.4 | 1.4 | | | | | |
| Inventory | -1.7 | | | | | | | |
| Prepaid expenses and other current assets | -1.6 | -1.3 | -0.7 | 0.8 | 0.7 | -0.3 | -0.1 | 1.5 |
| Operating lease right-of-use asset | 0.8 | -1.1 | | | | | | |
| Other non-current assets | -0.1 | | | 0.0 | 1.0 | -0.8 | 0.1 | 0.1 |
| Accounts payable | -0.7 | 1.9 | -2.0 | 1.1 | 0.3 | 0.8 | -1.8 | -1.0 |
| Accrued compensation and benefits | 1.9 | 1.8 | 0.2 | | | | | |
| Other accrued liabilities | 4.0 | 0.3 | -0.6 | 0.2 | 0.9 | -0.6 | -1.6 | -0.9 |
| Operating lease liability | -0.4 | 0.4 | | | | | | |
| Deferred revenue | -2.0 | -2.0 | -0.9 | 1.1 | -0.5 | -1.5 | | |
| Deferred research and development reimbursements | -0.2 | 0.1 | -0.4 | -0.7 | 1.1 | | | |
| Operating lease liability, non-current | -0.3 | 0.3 | | | | | | |
| Net cash used in operating activities | -57.3 | -38.0 | -2.9 | -25.0 | -19.2 | -31.1 | -18.2 | -54.2 |
| |
| Investing activities | | | | | | | | |
| Purchases of marketable securities | -28.2 | -36.1 | -17.9 | -6.7 | -34.9 | -29.4 | -19.1 | -42.3 |
| Proceeds from maturities and sales of marketable securities | 11.3 | 54.2 | | | | | | |
| Net cash provided by (used in) investing activities | -16.9 | 17.7 | -17.9 | 18.6 | -10.4 | -0.8 | -6.3 | 54.7 |
| |
| Financing activities | | | | | | | | |
| Proceeds from issuance of common stock, net of issuance costs | 55.1 | 53.6 | 30.3 | | | | | |
| Proceeds from warrant exercises | 3.1 | | | | | | | |
| Proceeds from issuance of stock for stock-based compensation arrangements | 0.6 | 0.0 | 0.0 | 0.5 | 0.0 | 0.0 | 0.3 | 0.2 |
| Proceeds from issuance of loan payable | 25.0 | 5.3 | | | | | | |
| |
| Payment of loan maturity fees (Note 6) | | | | | | | | |
| Payment of debt issuance costs | -0.1 | -0.3 | | | -0.1 | -0.1 | | -1.4 |
| Net cash provided by financing activities | 82.9 | 52.3 | 26.2 | 15.9 | 29.4 | 20.3 | -1.1 | 1.0 |
| |
| Supplemental cash flow information | | | | | | | | |
| Cash paid for interest | 2.9 | 1.3 | 2.0 | 2.0 | 2.1 | 1.5 | 2.0 | 2.0 |