| 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-K |
| Net revenue | 540.4 | 553.5 | 570.4 | 563.4 | 539.4 | 451.0 | 345.0 | 311.9 |
| Net revenue growth | -2.4% | -3.0% | 1.2% | 4.4% | 19.6% | 30.8% | 10.6% | 3316.6% |
| Operating expenses: | | | | | | | | |
| Cost of services | 128.9 | 119.2 | 115.2 | | | | | |
| Selling, general and administrative, including stock-based and long-term incentive compensation | 130.6 | 167.9 | 125.9 | 121.4 | 102.1 | 92.0 | 73.9 | 77.4 |
| Amortization of subscriber accounts, deferred contract acquisition costs and other intangible assets | 211.6 | 236.8 | 246.8 | 258.7 | 253.4 | 208.8 | 163.5 | 159.6 |
| Depreciation | 11.5 | 8.8 | 8.4 | 10.4 | 10.1 | 8.9 | 8.4 | 7.1 |
| Loss on goodwill impairment | 563.5 | | | | | | | |
| Total operating expenses | 1,046.2 | 511.9 | 514.7 | 514.0 | 461.3 | 379.5 | 295.3 | 289.6 |
| Operating income (loss) | -505.9 | 41.5 | 55.6 | 49.4 | 78.2 | 71.6 | 49.6 | 22.3 |
| Operating margin | -93.6% | 7.5% | 9.8% | 8.8% | 14.5% | 15.9% | 14.4% | 7.2% |
| |
| Other expense (income), net: | | | | | | | | |
| Interest income | -2.4 | -2.4 | -2.3 | -2.9 | -3.6 | -3.8 | -4.0 | -0.7 |
| Interest expense | -191.2 | -152.3 | -132.3 | -123.7 | -117.5 | -95.8 | -71.5 | -42.9 |
| Realized and unrealized (gain) loss, net on derivative financial instruments | 3.2 | | | | | | -2.0 | -10.6 |
| Refinancing expense | 13.4 | | 9.5 | | | | | |
| Other income, net | -1.5 | -0.2 | 0.1 | 4.5 | -1.6 | -2.2 | -3.7 | -4.0 |
| Total other expense (income), net | 203.8 | 149.6 | 139.6 | 129.1 | 112.2 | 89.9 | 72.0 | 48.7 |
| Income (loss) before income taxes | -709.7 | -108.1 | -84.0 | -79.7 | -34.0 | -18.3 | -22.4 | -26.4 |
| Income tax expense | -11.6 | -0.4 | 7.3 | 6.5 | 3.4 | 3.3 | 2.6 | 2.5 |
| Tax rate | 1.6% | 0.4% | | | | | | |
| Net income (loss) | -698.0 | -107.7 | -91.2 | -86.2 | -37.4 | -21.6 | -25.0 | -28.9 |
| |
| Other comprehensive income (loss): | | | | | | | | |
| Unrealized holding loss on marketable securities, net | -3.9 | 2.8 | 2.0 | 0.9 | -3.3 | -1.2 | 2.5 | 0.1 |
| Total other comprehensive income (loss), net of tax | 11.2 | 5.2 | 5.5 | -8.1 | -8.5 | 11.3 | -4.8 | -2.0 |
| Comprehensive income (loss) | -686.8 | -102.4 | -85.7 | -91.5 | -46.3 | -10.2 | -34.1 | 17.9 |
| |
| Basic earnings (loss) per share: | | | | | | | | |
| Net income (loss) (in dollars per share) | ($56.54) | ($8.82) | ($7.44) | ($6.44) | ($2.77) | ($1.54) | ($2.09) | $1.40 |
| |
| Diluted earnings (loss) per share: | | | | | | | | |
| Net income (loss) (in dollars per share) | ($56.54) | ($8.82) | ($7.44) | ($6.44) | ($2.77) | ($1.54) | ($2.09) | $1.40 |