| In millions, except per share items | Mar-31-18 | Dec-31-17 | Sep-30-17 | Jun-30-17 | Mar-31-17 | Dec-31-16 | Sep-30-16 | Jun-30-16 |
| | 10-Q | 10-K | 10-Q | 10-Q | 10-Q | 10-K | 10-Q | 10-Q |
| Assets | | | | | | | | |
| Current assets: | | | | | | | | |
| Cash and cash equivalents | 159.2 | 138.7 | 228.4 | 189.3 | 158.3 | 100.1 | 87.2 | 130.0 |
| Short-term investments | 9.0 | 18.5 | 39.0 | 55.3 | 68.3 | 90.9 | 95.5 | 69.1 |
| Restricted cash | 0.2 | 0.2 | 0.5 | 1.1 | 0.7 | 0.5 | 0.4 | 0.5 |
| Accounts receivable, net | 77.5 | 51.5 | 41.0 | 38.6 | 37.3 | 64.4 | 34.3 | 41.7 |
| Prepaid expenses and other current assets | 26.2 | 25.7 | 10.2 | 13.9 | 9.0 | 4.5 | 25.8 | 17.2 |
| Total current assets | 272.2 | 234.6 | 319.2 | 298.1 | 273.6 | 260.4 | 243.2 | 258.5 |
| Patent assets, net | 119.6 | 163.0 | 148.5 | 175.0 | 204.4 | 213.0 | 206.6 | 212.2 |
| Property and equipment, net | 5.0 | 5.1 | 5.7 | 6.3 | 6.6 | 6.9 | 7.2 | 8.0 |
| Intangible assets, net | 47.7 | 49.1 | 51.1 | 52.5 | 53.9 | 56.1 | 59.7 | 63.1 |
| Goodwill | 72.5 | 70.8 | 159.4 | 156.3 | 152.1 | 151.3 | 156.3 | 160.1 |
| Restricted cash, less current portion | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.1 |
| Deferred tax assets | 27.3 | 23.6 | 37.4 | 34.0 | 36.5 | 38.3 | 30.6 | 25.5 |
| Other assets | 19.0 | 3.7 | 9.5 | 10.3 | 9.6 | 8.3 | 8.9 | 8.5 |
| Total assets | 564.2 | 550.8 | 731.9 | 733.6 | 737.5 | 735.3 | 713.5 | 737.1 |
| |
| Liabilities and stockholders’ equity | | | | | | | | |
| Current liabilities: | | | | | | | | |
| Accounts payable | 3.6 | 2.2 | 3.1 | 2.5 | 2.4 | 3.2 | 2.2 | 3.0 |
| Accrued liabilities | 11.0 | 15.7 | 13.5 | 13.9 | 10.9 | 16.8 | 13.6 | 11.5 |
| Deferred revenue | 89.2 | 105.2 | 99.3 | 108.3 | 127.8 | 118.9 | 97.1 | 119.9 |
| Other current liabilities | 2.1 | 1.5 | 1.2 | 1.0 | 1.3 | 1.5 | 1.8 | 1.6 |
| Total current liabilities | 106.0 | 124.6 | 125.5 | 133.4 | 149.5 | 146.8 | 120.5 | 142.4 |
| Deferred revenue, less current portion | 0.3 | 1.7 | 3.7 | 6.2 | 8.5 | 11.6 | 5.6 | 3.3 |
| Deferred tax liabilities | 3.7 | 3.7 | 3.8 | 3.8 | 3.9 | 4.0 | 4.4 | 4.8 |
| Other liabilities | 11.0 | 11.1 | 10.8 | 10.5 | 10.6 | 10.5 | 8.6 | 8.4 |
| Total liabilities | 121.0 | 141.1 | 225.3 | 237.9 | 258.8 | 261.0 | 229.0 | 250.6 |
| |
| Commitments and contingencies (Note 11) | | | | | | | | |
| Stockholders’ equity: | | | | | | | | |
| Common stock | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Additional paid-in capital | 378.7 | 376.8 | 374.2 | 371.6 | 363.3 | 360.5 | 357.5 | 351.6 |
| Retained earnings | 68.4 | 39.4 | 139.3 | 134.7 | 130.8 | 130.2 | 137.9 | 141.4 |
| Accumulated other comprehensive loss | -4.0 | -6.5 | -7.0 | -10.6 | -15.5 | -16.4 | -10.9 | -6.5 |
| Total stockholders’ equity | 443.2 | 409.8 | 506.5 | 495.7 | 478.7 | 474.3 | 484.5 | 486.5 |
| Total liabilities and stockholders’ equity | 564.2 | 550.8 | 731.9 | 733.6 | 737.5 | 735.3 | 713.5 | 737.1 |