| 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: | | | | | | | | |
| Recurring | 201.0 | 162.6 | 129.9 | 99.8 | 81.7 | 70.9 | 63.0 | 53.0 |
| Services and license | 52.1 | 44.1 | 43.2 | 36.8 | 30.6 | 24.0 | 20.8 | 17.9 |
| Total revenue | 253.1 | 206.7 | 173.1 | 136.6 | 112.3 | 95.0 | 83.8 | 70.9 |
| Total revenue growth | 22.4% | 19.4% | 26.7% | 21.6% | 18.3% | 13.3% | 18.2% | -12.6% |
| Cost of revenue: | | | | | | | | |
| Recurring | 55.5 | 42.7 | 34.3 | 31.3 | 28.7 | 30.0 | 32.8 | 26.2 |
| Services and license | 43.0 | 35.4 | 32.1 | 24.8 | 19.0 | 20.3 | 16.5 | 15.7 |
| Total cost of revenue | 98.5 | 78.1 | 66.5 | 56.0 | 47.8 | 50.3 | 50.0 | 41.9 |
| Gross profit | 154.6 | 128.6 | 106.6 | 80.6 | 64.5 | 44.6 | 33.8 | 29.0 |
| Gross margin | 61.1% | 62.2% | 61.6% | 59.0% | 57.5% | 47.0% | 40.3% | 40.9% |
| |
| Operating expenses: | | | | | | | | |
| Sales and marketing | 93.4 | 78.6 | 58.8 | 47.0 | 34.9 | 32.4 | 20.2 | 16.2 |
| Research and development | 37.7 | 31.7 | 26.1 | 20.3 | 17.1 | 16.6 | 12.0 | 10.4 |
| General and administrative | 43.7 | 35.8 | 33.3 | 26.3 | 23.0 | 20.0 | 17.7 | 13.8 |
| Income from settlement and patent licensing | | -0.5 | -0.5 | | | | | |
| Restructuring and other | 1.2 | 0.5 | 0.6 | 1.0 | 1.7 | 1.1 | 0.6 | 1.7 |
| Total operating expenses | 176.0 | 292.7 | 237.1 | 188.8 | 152.9 | 68.5 | 101.9 | 42.2 |
| Operating loss | -21.4 | -17.4 | -11.7 | -13.5 | -11.7 | -23.9 | -16.8 | -13.2 |
| Operating margin | -8.5% | -8.4% | -6.7% | -9.9% | -10.4% | -25.2% | -20.1% | -18.6% |
| Interest income and other income (expense), net | 1.0 | -0.4 | -0.5 | 3.5 | -2.9 | -3.4 | -1.9 | 0.0 |
| Interest expense | -0.1 | -0.3 | -0.2 | -0.5 | -3.2 | -3.5 | -2.5 | -0.1 |
| Loss before provision (benefit) for income taxes | -20.5 | -17.8 | -12.4 | -10.5 | -19.4 | -27.3 | -18.8 | -13.2 |
| Provision (benefit) for income taxes | -0.2 | 1.1 | 0.8 | 1.0 | 2.1 | 0.4 | -2.9 | -0.5 |
| Tax rate | 1.1% | | | | | | 15.6% | 3.6% |
| Net loss | -20.3 | -19.0 | -13.1 | -11.6 | -21.4 | -27.7 | -15.8 | -12.7 |
| |
| Net loss per share—basic and diluted: | | | | | | | | |
| Net loss per share (in dollars per share) | ($0.31) | ($0.32) | ($0.24) | ($0.24) | ($0.55) | ($0.78) | ($0.48) | ($0.40) |
| |
| Shares used in basic and diluted per share computation (in shares) | 65.3 | 58.9 | 54.7 | 47.5 | 38.9 | 35.4 | 32.8 | 31.5 |
| |
| Comprehensive loss: | | | | | | | | |
| Net loss | -20.3 | -19.0 | -13.1 | -11.6 | -21.4 | -27.7 | -15.8 | -12.7 |
| Unrealized losses on available-for-sale securities | -0.2 | 0.0 | 0.0 | | | | | |
| Foreign currency translation adjustments | 4.3 | -3.4 | -1.0 | -0.9 | -0.1 | 0.0 | 0.0 | -0.1 |
| Comprehensive loss | -16.2 | -22.4 | -14.1 | -12.5 | -21.5 | -27.6 | -15.5 | -13.1 |