| 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 |
| Cash Flows From Operating Activities: | | | | | | | | |
| Net Loss | -32.7 | -30.9 | -34.1 | -32.1 | -25.9 | -19.8 | -14.4 | -21.3 |
| Adjustments To Reconcile Net Loss To Net Cash Used In Operating Activities: | | | | | | | | |
| Depreciation and Amortization | 0.7 | 0.8 | 0.8 | 0.7 | 0.5 | 0.8 | 0.8 | 1.0 |
| Stock-based Compensation | 0.9 | 0.5 | 5.0 | 4.4 | 7.2 | 10.3 | 8.9 | 10.1 |
| Increase in Inventory Reserves | 0.1 | 0.3 | 1.3 | 8.8 | | | | |
| Amortization of Debt Financing Costs and Accretion of Debt Discount | 0.4 | 0.3 | | | | | | |
| Loss on Disposal of Assets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Changes in operating Assets and Liabilities: | | | | | | | | |
| Accounts Receivable, net | -1.7 | 0.0 | 2.8 | -0.6 | -1.0 | -1.2 | -0.6 | 0.1 |
| Inventory | -0.7 | -1.3 | 0.3 | -0.8 | 0.3 | -6.1 | -4.0 | -1.1 |
| Accounts Payable | -0.4 | 1.1 | -1.5 | 0.3 | -1.6 | 1.9 | -1.3 | -3.4 |
| Other Liabilities | 0.0 | 0.5 | -0.5 | 0.3 | 0.6 | 0.2 | -0.4 | -2.3 |
| Changes in operating Assets and Liabilities | -4.8 | -3.0 | -2.0 | -3.4 | -3.7 | -3.8 | -8.7 | 12.7 |
| Cash Used In Operating Activities | -33.5 | -29.6 | -27.3 | -20.4 | -21.1 | -12.5 | -13.3 | 4.3 |
| |
| Cash Flows From Investing Activities: | | | | | | | | |
| Purchase of Investments Available-for-Sale | -26.1 | -29.3 | -41.7 | | | 25.8 | 21.8 | -13.1 |
| Sale of Investments Available-for-Sale | 26.9 | 33.6 | 38.3 | 33.9 | 51.9 | 24.5 | 1.5 | 5.0 |
| Purchase of Equipment | -0.5 | -1.0 | -0.6 | -0.7 | -1.7 | -0.4 | -0.8 | -0.7 |
| Cash Provided by Investing Activities | 0.3 | 3.2 | -4.8 | 12.7 | 14.5 | -1.6 | -21.1 | -8.8 |
| |
| Cash Flows From Financing Activities: | | | | | | | | |
| Payments on Debt | -2.3 | -0.8 | | | | | | |
| Payments on Insurance Financing Note Payable | -1.5 | -0.8 | -1.1 | | | | | |
| Proceeds from the Issuance of Common Stock | | | | | 0.1 | | | |
| Cash (Used In) Provided by Financing Activities | -2.2 | 63.3 | 21.1 | 22.0 | -2.2 | 0.1 | -0.1 | 58.5 |
| |
| Supplemental Disclosure of Cash Flow Information: | | | | | | | | |
| Cash Paid for Interest | 1.8 | 1.6 | | | | | | 3.5 |
| Supplemental Disclosure of Noncash Investing and Financing Activities: | | | | | | | | |