| In millions, except per share items | Dec-31-10 | Dec-31-09 | Dec-31-08 | Dec-31-07 | Dec-31-06 | Dec-31-05 | Jan-31-05 | Aug-31-04 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net revenue | 2,859.3 | 2,569.7 | 2,409.9 | 2,107.0 | 1,934.2 | 1,655.5 | 696.2 | 1,604.6 |
| Net revenue growth | 11.3% | 6.6% | 14.4% | 8.9% | 16.8% | | | |
| Depreciation and amortization expense | 65.3 | 64.4 | 69.0 | 70.5 | | | | |
| Income from operations | 246.0 | 213.1 | 168.2 | 132.6 | | | | |
| Operating margin | 8.6% | 8.3% | 7.0% | 6.3% | | | | |
| Interest income from restricted assets | 3.1 | 4.5 | 6.4 | 7.1 | | | | |
| Interest expense | -22.9 | -41.0 | -42.1 | -46.9 | | | | |
| Realized (loss) gain on investments | 2.5 | 2.1 | 2.7 | 0.2 | | | | |
| Income before income taxes and equity in earnings of unconsolidated subsidiary | 210.5 | 180.6 | 137.1 | 95.1 | 63.6 | 34.4 | 15.8 | 59.1 |
| Income tax expense | -79.1 | -65.7 | -52.5 | -36.1 | | | | |
| Tax rate | 37.6% | 36.4% | 38.3% | 38.0% | | | | |
| Income before equity in earnings of unconsolidated subsidiary | 131.4 | 114.9 | 84.5 | 59.0 | | | | |
| |
| Other comprehensive income, net of tax: | | | | | | | | |
| |
| Unrealized gains on derivative financial instruments | | | | | | | | |
| Comprehensive income | | | | | | | | |
| Basic earnings per common share (in dollars per share) | $3.00 | $2.71 | $2.04 | $1.44 | | | | |
| Diluted earnings per common share (in dollars per share) | $2.95 | $2.64 | $1.97 | $1.39 | | | | |
| |
| Weighted average common shares outstanding, basic (in shares) | 44.0 | 42.6 | 41.7 | 41.6 | | | | |
| Weighted average common shares outstanding, diluted (in shares) | 44.7 | 43.6 | 43.1 | 43.1 | | | | |
| |
| Restructuring charges | | | | | | | | |
| Net income | | | | | | | | |
| Comprehensive income | | | | | | | | |
| Loss on early debt extinguishment | | | | | | | | |
| Interest and other (expense) income | | | | | | | | |