| In millions, except per share items | Dec-31-15 | Dec-31-14 | Dec-31-13 | Dec-31-12 |
| | 10-K | 10-K | 10-K | 10-K |
| Revenues | | | | |
| Other income | 0.9 | 0.8 | 0.7 | 0.3 |
| Total revenues | 435.8 | 259.1 | 89.9 | 50.8 |
| Total revenues growth | 68.2% | 188.1% | 77.2% | |
| Expenses | | | | |
| Commission expense (refer to Note 3) | 117.4 | 104.4 | 57.3 | 38.5 |
| Interest expense | 0.8 | | | |
| Transaction costs | 9.7 | 24.5 | 1.6 | |
| Other expenses | 3.5 | 1.5 | 0.1 | 0.3 |
| |
| General and administrative expenses | | | | |
| Other general and administrative expenses | 33.4 | 17.7 | 6.4 | 4.8 |
| Total general and administrative expenses | 159.2 | 106.6 | 32.9 | 29.3 |
| Total expenses | 682.1 | 528.9 | 211.6 | 161.2 |
| |
| Unrealized gain (loss) on investments and other | | | | |
| Income | 141.0 | 21.8 | -2.0 | -17.3 |
| Equity in earnings (losses) of unconsolidated ventures (refer to Note 4) | -1.6 | -1.0 | | |
| Income (loss) before income tax benefit (expense) | 142.6 | 20.7 | -2.0 | -17.3 |
| Income tax benefit (expense) | -21.9 | -1.6 | | |
| Tax rate | 15.5% | 7.5% | 0.0% | 0.0% |
| Net income (loss) | 120.7 | 19.1 | -2.0 | -17.3 |
| Net (income) loss attributable to non-controlling interests | -1.0 | | | |
| |
| Net (income) loss attributable to redeemable non-controlling interests | | | | |
| Net income (loss) attributable to NorthStar Asset Management Group Inc. common stockholders | 119.8 | 19.1 | -2.0 | -17.3 |
| |
| Earnings (loss) per share: | | | | |
| Basic (in dollars per share) | $0.61 | $0.10 | ($0.01) | ($0.09) |
| Diluted (in dollars per share) | $0.60 | $0.10 | ($0.01) | ($0.09) |
| |
| Weighted average number of shares: | | | | |
| Basic (shares) | 188.7 | 187.9 | 187.8 | 187.8 |
| Dilutive (shares) | 193.1 | 190.4 | 187.8 | 187.8 |
| |
| Equity-based compensation expense | 57.5 | 51.7 | 5.2 | 4.2 |