| 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/A | 10-K/A | 10-K/A | 10-K | 10-K | 10-K | 10-K | 10-K |
| Revenues: | | | | | | | | |
| Total Revenues | | | | 614.0 | 501.2 | 473.3 | 428.8 | 409.4 |
| Total Revenues growth | | | | 22.5% | 5.9% | 10.4% | 4.7% | 1.1% |
| Operating costs and expenses: | | | | | | | | |
| Cost of sales | | | | 263.0 | 179.5 | 168.3 | 141.4 | 128.3 |
| Selling and marketing expense | | | | 62.0 | 53.7 | 53.6 | 53.5 | 50.8 |
| General and administrative expense | | | | 133.0 | 112.6 | 105.3 | 94.5 | 89.0 |
| Amortization expense of intangibles | | | | 12.0 | 8.1 | 23.0 | 27.3 | 26.4 |
| Depreciation expense | | | | 16.0 | 14.5 | 13.4 | 13.3 | 10.5 |
| Total operating costs and expenses | | | | 981.0 | 368.5 | 363.6 | 330.0 | 305.0 |
| Operating income | | | | 127.0 | 132.7 | 109.8 | 98.8 | 104.5 |
| Operating margin | | | | 20.7% | 26.5% | 23.2% | 23.0% | 25.5% |
| |
| Other income (expense): | | | | | | | | |
| Interest income | | | | | 0.4 | 1.8 | 1.3 | 0.4 |
| Interest expense | | | | -7.0 | -6.2 | -25.6 | -35.6 | -35.8 |
| Other income (expense), net | | | | 2.0 | 0.3 | -2.5 | 1.6 | -0.3 |
| Equity in earnings from unconsolidated entities | | | | 5.0 | | | | |
| Total other income (expense), net | | | | 2.0 | -5.6 | -44.8 | -32.7 | -35.6 |
| Income tax provision | | | | -45.0 | -45.4 | -24.3 | -24.9 | -26.5 |
| Net income | | | | 82.0 | 81.8 | 40.7 | 41.1 | 42.4 |
| Net income attributable to noncontrolling interests | | | | -3.0 | 0.6 | 0.0 | | 0.0 |
| Net income attributable to common stockholders | | | | 79.0 | | 40.7 | 41.1 | |
| |
| Earnings per share attributable to common stockholders: | | | | | | | | |
| Basic (in dollars per share) | | | | $1.38 | $1.42 | $0.72 | $0.72 | $0.75 |
| Diluted (in dollars per share) | | | | $1.36 | $1.40 | $0.71 | $0.71 | $0.73 |
| |
| Weighted average number of shares of common stock outstanding (in 000's): | | | | | | | | |
| Basic (in shares) | | | | 57.3 | 57.2 | 56.5 | 57.0 | 56.9 |
| Diluted (in shares) | | | | 58.0 | 57.8 | 57.2 | 57.8 | 57.8 |
| |
| Dividends declared per share of common stock (in dollars per share) | | | | $0.44 | $0.33 | $0.50 | | |