| In millions, except per share items | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 | Dec-31-13 | Dec-31-12 | Dec-31-11 | Dec-31-10 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Revenue | 54.4 | 63.2 | 62.6 | 69.8 | 77.7 | 92.5 | 140.8 | 156.1 |
| Revenue growth | -14.0% | 1.1% | -10.4% | -10.2% | -16.0% | -34.3% | -9.8% | -8.9% |
| Cost of revenue and operating expenses: | | | | | | | | |
| Research and development | 8.0 | 7.3 | 10.0 | 11.9 | 13.3 | 13.7 | 14.4 | 13.8 |
| Sales and marketing | 10.2 | 11.2 | 10.3 | 15.8 | 16.4 | 17.9 | 20.7 | 24.9 |
| General and administrative | 11.5 | 10.8 | 14.7 | 18.1 | 20.4 | 20.4 | 20.0 | 19.8 |
| Operating loss | -20.1 | -7.3 | -14.9 | -19.4 | -14.9 | -6.0 | -2.5 | -3.5 |
| Operating margin | -36.9% | -11.6% | -23.8% | -27.9% | -19.2% | -6.5% | -1.8% | -2.2% |
| |
| Other income (expense): | | | | | | | | |
| Interest income (expense), net | 0.1 | 0.0 | -0.1 | -0.1 | 0.0 | 0.0 | 0.1 | 0.1 |
| Foreign exchange gain (loss) | -0.4 | -0.2 | -0.1 | -0.1 | -0.5 | -0.3 | -0.5 | 0.1 |
| Total other income (expense) | | | | 0.3 | 0.0 | 0.0 | 0.1 | 0.0 |
| Loss before provision for income taxes | -20.4 | -7.5 | -15.2 | -19.3 | -15.5 | -6.3 | -2.7 | -3.3 |
| Provision for income taxes | 0.2 | 0.2 | 0.3 | -7.1 | -0.8 | -0.3 | 0.3 | -0.2 |
| Tax rate | | | | 36.8% | 5.0% | 4.3% | | 5.8% |
| Net loss | -20.6 | -7.8 | -15.5 | 7.0 | -12.3 | -4.4 | -3.0 | -3.1 |
| Comprehensive loss | -20.6 | -7.8 | -15.5 | 7.0 | -12.3 | -4.4 | -3.0 | -3.1 |
| |
| Total net income (loss) per share (in dollars per share) | | | | $0.11 | ($0.19) | ($0.07) | ($0.05) | ($0.05) |
| |
| Weighted average shares outstanding - basic and diluted (in shares) | 66.1 | 64.3 | 62.9 | 62.6 | 63.4 | 60.7 | 58.4 | 58.7 |