| In millions, except per share items | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 | Sep-23-13 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Revenue | 3,183.4 | 3,066.3 | 2,871.9 | 2,259.4 | 502.5 | 1,613.9 | 1,459.6 | 379.2 |
| Revenue growth | 3.8% | 6.8% | 27.1% | 349.6% | -68.9% | 10.6% | | |
| Operating expenses: | | | | | | | | |
| Cost of revenue | | | | | | | | |
| Selling, general and administrative expenses | 453.0 | 394.9 | 371.8 | 322.0 | 269.9 | 246.4 | 254.0 | 69.7 |
| Transaction-related costs | -44.5 | 1.8 | 35.8 | 87.7 | 44.8 | | | |
| Depreciation and amortization expense | 131.6 | 114.9 | 112.2 | 78.2 | 69.5 | 78.0 | 96.6 | 25.3 |
| Loss on disposal of fixed assets | 0.3 | 1.1 | 0.1 | 0.4 | 0.8 | 0.7 | 0.0 | |
| Income from operations | 328.1 | 363.9 | 281.3 | 176.2 | 162.3 | 164.3 | 56.8 | -22.7 |
| Operating margin | 10.3% | 11.9% | 9.8% | 7.8% | 32.3% | 10.2% | 3.9% | -6.0% |
| Interest expense, net | -43.1 | -52.0 | -57.4 | -46.7 | -54.9 | -61.7 | -81.9 | -23.7 |
| Loss on modification or extinguishment of debt | -1.0 | -3.9 | -1.0 | | | | | |
| Foreign currency losses, net | -25.5 | -2.3 | -1.0 | -39.6 | 24.0 | 14.0 | 10.5 | |
| Other (expense) income, net | 0.0 | 0.2 | -0.4 | -0.3 | 0.6 | -1.4 | -2.3 | 1.2 |
| Income before income taxes and equity in income of unconsolidated joint ventures | 259.0 | 305.9 | 221.5 | 74.5 | 93.9 | 115.2 | -41.9 | -57.1 |
| Provision for income taxes | 62.0 | 62.8 | 67.2 | -12.6 | 28.5 | 30.0 | -8.2 | -17.2 |
| Tax rate | 23.9% | 20.5% | 30.3% | | 30.3% | 26.1% | 19.5% | 30.1% |
| Income before equity in income of unconsolidated joint ventures | 197.0 | 243.1 | 154.3 | | | | | |
| Equity in income of unconsolidated joint ventures, net of tax | | | 0.1 | 0.1 | 2.8 | -3.4 | 2.0 | 0.6 |
| Net income | 197.0 | 243.1 | 154.5 | 87.3 | 68.2 | | | |
| Net income attributable to noncontrolling interest | | -0.1 | -0.6 | -0.4 | | | | |
| Net income attributable to PRA Health Sciences, Inc. | 197.0 | 243.0 | 153.9 | 86.9 | 68.2 | 81.8 | | -39.9 |
| |
| Net income per share attributable to common stockholders: | | | | | | | | |
| Basic (in dollars per share) | $3.11 | $3.77 | $2.40 | $1.39 | $1.12 | $1.36 | ($0.83) | ($1.02) |
| Diluted (in dollars per share) | $3.04 | $3.68 | $2.32 | $1.32 | $1.06 | $1.29 | ($0.83) | ($1.02) |
| |
| Weighted average common shares outstanding: | | | | | | | | |
| Basic (in shares) | 63.4 | 64.5 | 64.1 | 62.4 | 60.8 | 60.0 | 42.9 | 39.3 |
| Diluted (in shares) | 64.8 | 66.0 | 66.3 | 65.8 | 64.5 | 63.2 | 42.9 | 39.3 |