| In millions, except per share items | Sep-30-21 | Jun-30-21 | Dec-31-20 | Sep-30-20 | Jun-30-20 | Mar-31-20 | Dec-31-19 | Sep-30-19 |
| | 10-Q | 10-Q | 10-K | 10-Q | 10-Q | 10-Q | 10-K | 10-Q |
| Assets | | | | | | | | |
| Current assets: | | | | | | | | |
| Cash and cash equivalents | 65.8 | 60.7 | 49.2 | 46.8 | 44.3 | 37.7 | 43.0 | 36.0 |
| Accounts receivable and other, net | 23.3 | 21.7 | 31.7 | 30.5 | 33.2 | 38.1 | 31.4 | 35.4 |
| Prepaid expenses and other current assets | 7.1 | 8.7 | 3.8 | 4.4 | 5.6 | 5.3 | 4.6 | 4.5 |
| Total current assets | 96.1 | 91.2 | 84.8 | 81.7 | 83.1 | 87.0 | 95.5 | 96.0 |
| Property and equipment, net | 4.3 | 4.5 | 5.3 | 5.7 | 6.4 | 6.8 | 4.9 | 3.3 |
| Restricted cash, non-current | | | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | 1.3 |
| Deferred commissions | 7.1 | 7.2 | 9.6 | 10.6 | 11.7 | 12.7 | 14.7 | 17.2 |
| Deferred professional service costs | 3.6 | 3.9 | 4.5 | 5.3 | 5.7 | 6.2 | 6.7 | 8.4 |
| Intangible assets, net | 4.8 | 5.8 | 7.9 | 9.0 | 10.0 | 11.1 | 12.2 | 13.3 |
| Goodwill | 41.5 | 41.5 | 41.5 | 41.5 | 41.5 | 41.5 | 91.8 | 91.8 |
| Operating lease right-of-use assets, net | 6.9 | 8.0 | 10.2 | 11.4 | 11.1 | 12.3 | 13.9 | 13.4 |
| Other assets | 0.1 | 0.1 | 1.9 | 1.7 | 1.6 | 1.9 | 2.0 | 2.1 |
| Total assets | 164.4 | 162.1 | 166.8 | 168.0 | 172.3 | 180.7 | 242.8 | 246.8 |
| |
| Liabilities and stockholders’ equity | | | | | | | | |
| Current liabilities: | | | | | | | | |
| Accounts payable | 4.5 | 3.7 | 5.1 | 4.7 | 8.6 | 13.3 | 19.6 | 12.0 |
| Accrued expenses and other current liabilities | 9.4 | 7.1 | 14.8 | 8.2 | 8.9 | 10.4 | 14.6 | 11.2 |
| Accrued compensation | 9.4 | 7.1 | 8.6 | 6.8 | 5.7 | 4.3 | 8.8 | 5.5 |
| Deferred revenue | 9.7 | 10.0 | 6.8 | 10.2 | 12.9 | 13.7 | 10.2 | 17.5 |
| Operating lease liabilities | 5.0 | 6.1 | 5.8 | 5.7 | 5.4 | 5.4 | 5.9 | 5.9 |
| Total current liabilities | 32.6 | 32.1 | 34.3 | 35.6 | 41.5 | 47.2 | 54.9 | 52.1 |
| Deferred revenue, non-current | 0.2 | 0.1 | 0.7 | 0.4 | 0.6 | 0.6 | 0.6 | 0.8 |
| Operating lease liabilities, non-current | 4.0 | 4.3 | 7.4 | 9.0 | 9.3 | 10.6 | 11.8 | 10.6 |
| Other liabilities, non-current | 0.5 | 0.3 | 0.5 | 0.9 | 1.3 | 1.2 | 1.2 | 1.1 |
| Total liabilities | 37.3 | 36.9 | 42.9 | 45.9 | 53.1 | 60.6 | 69.9 | 66.5 |
| |
| Commitments and contingencies | | | | | | | | |
| Stockholders’ equity: | | | | | | | | |
| Common stock | | | | | | | | |
| Additional paid-in capital | 651.7 | 647.8 | 641.1 | 638.1 | 634.7 | 631.4 | 627.9 | 623.6 |
| Accumulated deficit | -524.6 | -522.6 | -517.2 | -516.0 | -515.6 | -511.4 | -455.0 | -443.3 |
| Total stockholders’ equity | 127.1 | 125.3 | 123.9 | 122.1 | 119.2 | 120.1 | 172.9 | 180.3 |
| Total liabilities and stockholders’ equity | 164.4 | 162.1 | 166.8 | 168.0 | 172.3 | 180.7 | 242.8 | 246.8 |