| In millions, except per share items | Dec-31-15 | Dec-31-14 | Dec-31-13 | Dec-31-12 | Dec-31-11 | Dec-31-10 | Dec-31-09 | Dec-31-08 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Operating Activities | | | | | | | | |
| Net loss | -38.1 | -39.8 | -24.0 | -12.1 | -4.3 | -2.4 | | |
| |
| Adjustments to reconcile net loss to net cash used in operating activities: | | | | | | | | |
| Amortization of Intangible Assets | 3.0 | 3.1 | 2.8 | 2.3 | 1.6 | 1.7 | | |
| Provision for bad debts | 0.0 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 | | |
| Allowance for sales adjustments | 0.2 | 0.0 | 0.0 | 0.1 | 0.0 | 0.0 | | |
| Provision for inventory obsolescence | 0.5 | 0.1 | 0.0 | 0.4 | 1.1 | 0.3 | | |
| Deferred rent | -0.1 | 0.3 | 0.0 | | | | | |
| Stock-based compensation | 4.8 | 5.6 | 5.3 | 2.2 | 1.6 | 0.7 | | |
| Deferred income taxes | -2.7 | 0.0 | 0.1 | -2.5 | 0.1 | 0.2 | | |
| Loss on disposal of equipment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | | |
| Changes in operating assets and liabilities: | | | | | | | | |
| Accounts receivable | 0.3 | -1.4 | -0.3 | -0.3 | -0.8 | -2.1 | | |
| Notes receivable | 0.3 | -1.4 | -0.3 | -0.3 | -0.8 | -2.1 | | |
| Inventories | -9.1 | 2.6 | -3.0 | -3.3 | -0.3 | -1.1 | | |
| Prepaid expenses and other assets | 1.8 | 0.2 | -0.7 | -0.8 | -0.4 | -0.1 | | |
| Accounts payable | -1.6 | 0.7 | 0.6 | -0.4 | 0.2 | 0.4 | | |
| Accrued expenses and other liabilities | 4.6 | 1.6 | 0.9 | 1.4 | 0.2 | 0.8 | | |
| Net cash used in operating activities | -35.4 | -26.0 | -17.2 | -11.9 | 0.2 | -0.3 | | |
| |
| Investing Activities | | | | | | | | |
| Acquisition of a business, net of cash acquired | | | | -14.4 | | | | |
| Purchase of investments | -55.0 | -91.5 | -33.7 | -6.5 | -5.5 | | | |
| Proceeds from sale of investments | 86.0 | 50.5 | 14.5 | 7.7 | | | | |
| Purchase of equipment and improvements | -1.8 | -1.7 | -0.7 | -0.8 | -1.0 | -0.6 | | |
| Net cash provided by investing activities | 29.2 | -43.9 | -20.3 | -16.2 | -7.5 | -2.9 | | |
| |
| Financing Activities | | | | | | | | |
| Proceeds fro m issuance of common stock, net of issuance costs | | 80.6 | | 51.5 | 27.0 | 4.5 | | |
| Payment of withholding taxes related to employee stock-based compensation | -0.2 | -0.3 | -0.2 | -0.1 | | | | |
| Net cash provided by financing activities | 1.8 | 82.6 | 2.6 | 52.6 | 23.9 | 3.2 | | |
| |
| Effect of exchange rate changes on cash and cash equivalents | 0.8 | 0.2 | -0.2 | 0.0 | 0.0 | 0.1 | | |
| Net increase (decrease) in cash and cash equivalents | -3.6 | 12.9 | -35.1 | 24.5 | 16.7 | 0.2 | | |
| |
| Cash and cash equivalents | | | | | | | | |
| Beginning of period | 19.4 | 6.5 | 41.6 | 17.1 | 0.4 | 0.2 | | |
| End of period | 15.8 | 19.4 | 6.5 | 41.6 | 17.1 | 0.4 | | |
| |
| Supplemental disclosures of cash flow information: | | | | | | | | |
| Non-cash investing and financing activities | | | | | | | | |
| Issuance of common stock | | | | | | -2.4 | | |
| Cash paid during the period for: | | | | | | | | |
| Taxes | 0.0 | 0.1 | | | 0.3 | 0.1 | | |