| In millions, except per share items | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 | Dec-31-13 | Dec-31-12 | Dec-31-11 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-Q/A |
| ASSETS | | | | | | | | |
| Current assets: | | | | | | | | |
| Cash and cash equivalents | 58.0 | 46.2 | 25.4 | 24.4 | 24.7 | 30.6 | 28.7 | 29.3 |
| Trade and other accounts receivable, net of allowance for doubtful accounts of $12 and $0 as of March 31, 2019 and December 31, 2018, respectively | 20.0 | 22.7 | 20.4 | 43.2 | 43.7 | 29.9 | 33.4 | 28.0 |
| Inventories | 33.6 | 23.5 | 32.2 | 39.1 | 44.9 | 44.7 | 41.6 | 33.2 |
| Prepaid expenses and other current assets | 2.8 | 2.2 | 4.4 | 2.6 | 2.4 | 2.3 | 3.2 | 3.2 |
| Total current assets | 114.5 | 117.0 | 82.5 | 109.6 | 115.7 | 107.6 | 107.0 | 93.6 |
| Property and equipment, net | 24.4 | 20.0 | 26.1 | 32.3 | 39.2 | 44.9 | 36.2 | 28.5 |
| Intangible assets, net | 10.0 | 11.7 | | | | | 0.7 | 1.1 |
| Goodwill | 14.2 | 14.7 | 22.8 | 23.6 | 23.6 | 26.0 | 25.4 | 24.9 |
| Other non-current assets | 0.7 | 0.9 | 0.6 | 0.6 | 0.7 | 1.0 | 0.2 | 0.2 |
| Total assets | 163.7 | 205.4 | 140.9 | 172.0 | 186.6 | 190.1 | 176.5 | 154.7 |
| |
| LIABILITIES AND STOCKHOLDERS’ EQUITY | | | | | | | | |
| Current liabilities: | | | | | | | | |
| Accounts payable and accrued liabilities | 16.5 | 27.3 | 38.4 | 34.0 | 27.0 | 25.6 | 27.2 | 36.1 |
| Accrued employee compensation | 7.1 | 8.4 | 6.2 | 6.7 | 9.3 | 8.8 | 4.7 | 6.3 |
| Deferred revenue and other current liabilities | 4.3 | 6.6 | | | | | | |
| Short-term borrowings and current portion of long-term debt | 0.4 | 0.0 | 0.0 | 0.0 | 15.5 | 7.9 | 9.5 | 5.4 |
| Total current liabilities | 28.4 | 48.5 | 29.3 | 43.8 | 53.7 | 44.3 | 49.0 | 49.7 |
| Deferred tax liability, long-term | 0.1 | 5.0 | 8.6 | 6.1 | 3.3 | 2.1 | 1.4 | 0.9 |
| Long-term debt, excluding current portion | 38.0 | 35.0 | 0.0 | 0.0 | 0.0 | 0.1 | 0.1 | 0.1 |
| Defined benefit plan liability | 4.5 | 3.9 | | | | | | |
| Other long-term liabilities | 2.3 | 2.8 | 2.1 | 2.9 | 2.6 | 3.4 | 1.0 | 3.0 |
| Total liabilities | 73.1 | 99.3 | 40.1 | 52.8 | 59.6 | 49.9 | 51.5 | 53.7 |
| |
| Commitments and contingencies (Note 14) | | | | | | | | |
| Stockholders’ equity: | | | | | | | | |
| Common stock | 4.6 | 3.7 | 3.2 | 3.2 | 3.0 | 3.0 | 2.9 | 2.8 |
| Additional paid-in capital | 369.8 | 337.5 | 296.3 | 291.5 | 277.3 | 271.9 | 267.6 | 252.9 |
| Accumulated deficit | -283.5 | -247.2 | -204.1 | -180.4 | -158.1 | -151.8 | -158.1 | -165.3 |
| Accumulated other comprehensive income | -0.3 | 12.1 | 5.4 | 4.9 | 4.7 | 17.1 | 12.5 | 10.6 |
| Total stockholders’ equity | 90.6 | 106.1 | 100.8 | 119.2 | 127.0 | 140.2 | 124.9 | 101.0 |
| Total liabilities and stockholders’ equity | 163.7 | 205.4 | 140.9 | 172.0 | 186.6 | 190.1 | 176.5 | 154.7 |