| In millions, except per share items | Dec-31-22 | Dec-31-21 | Dec-31-20 | Dec-05-19 | Dec-31-18 | Dec-05-18 | Dec-31-17 | Dec-05-17 |
| | 10-K | 10-K | 10-K | 10-K/A | 10-K | 10-K/A | 10-K | 10-K/A |
| Revenues | | | | | | | | |
| Investment banking | 494.8 | 1,067.2 | 769.5 | | 357.2 | | 223.6 | |
| Brokerage | 592.3 | 585.2 | 524.4 | | 413.6 | | 293.6 | |
| Securities principal transactions, net | 112.8 | 122.1 | 124.7 | | | | | |
| |
| Portfolio fund principal transactions, net | | | | | | | | |
| Carried interest allocations | | | | | | | | |
| Total investment income (loss) | 76.8 | 127.5 | 204.4 | | | | | |
| Management fees | 66.7 | 72.3 | 47.5 | | | | | |
| Incentive income | 0.6 | 2.7 | 0.6 | | | | | |
| Interest and dividends | 312.1 | 219.3 | 187.5 | | 108.0 | | 49.4 | |
| Insurance and reinsurance premiums | 36.5 | 39.6 | 30.1 | | | | | |
| Other revenues | 7.0 | 5.2 | 10.5 | | 4.5 | | 8.6 | |
| |
| Consolidated Funds | | | | | | | | |
| Interest and dividends | | 0.0 | 5.2 | | | | | |
| Other revenues | 0.0 | | 0.6 | | 0.0 | | 1.5 | |
| Total revenues | 1,139.2 | 1,718.2 | 1,338.5 | 109.5 | 966.9 | 6.9 | 658.8 | 66.7 |
| Total revenues growth | -33.7% | 28.4% | | 1495.4% | 46.8% | -89.7% | 39.7% | |
| Interest and dividends expense | 259.1 | 211.4 | 187.7 | | | | | |
| |
| Expenses | | | | | | | | |
| Brokerage and trade execution costs | 162.6 | 153.8 | 139.0 | | | | | |
| Professional, advisory and other fees | 80.6 | 80.8 | 60.0 | | 41.0 | | 31.9 | |
| Service fees | 29.9 | 25.8 | 25.4 | | 20.2 | | 15.0 | |
| Communications | 38.0 | 37.5 | 32.6 | | 30.8 | | 23.5 | |
| Occupancy and equipment | 41.7 | 40.7 | 36.6 | | 41.6 | | 35.2 | |
| Depreciation and amortization | 27.7 | 19.0 | 22.7 | | 12.4 | | 13.1 | |
| Client services and business development | 39.3 | 29.6 | 20.5 | | 35.9 | | 28.3 | |
| Insurance and reinsurance claims, commissions and amortization of deferred acquisition costs | -12.3 | 33.9 | 33.9 | | | | | |
| Other expenses | 41.1 | 22.3 | 25.9 | | 22.9 | | 19.4 | |
| |
| Consolidated Funds | | | | | | | | |
| Interest and dividends | | | 2.1 | | | | | |
| Professional, advisory and other fees | 0.1 | 0.3 | 2.1 | | | | | |
| Brokerage and trade execution costs | | | 0.0 | | | | | |
| Other expenses | 41.1 | 22.3 | 25.9 | | 22.9 | | 19.4 | |
| Total expenses | 1,211.6 | 1,530.2 | 1,292.4 | | 887.6 | | 696.6 | |
| |
| Other income (loss) | | | | | | | | |
| Bargain purchase gain, net of tax | | 3.9 | | | | | | |
| Total other income (loss) | 9.6 | 34.8 | 21.6 | | 123.7 | | 105.8 | |
| Income (loss) before income taxes | 76.6 | 406.0 | 297.4 | | 98.9 | | 7.0 | |
| Income tax expense (benefit) | 10.8 | 102.0 | 90.4 | | 15.7 | | 44.1 | |
| Net income (loss) | 65.9 | 304.0 | 207.1 | | 83.2 | | -37.1 | |
| Net income (loss) attributable to non-controlling interests in consolidated subsidiaries and investment funds | -10.6 | 8.4 | -9.3 | | | | | |
| Net income (loss) attributable to Cowen Inc. | 76.5 | 295.6 | 216.4 | 110.4 | 42.8 | 7.0 | -60.9 | 67.0 |
| Preferred stock dividends | 6.8 | 6.8 | 6.8 | | 6.8 | | 6.8 | |
| Net income (loss) attributable to Cowen Inc. common stockholders | 69.7 | 288.8 | 209.6 | | 36.0 | | -67.7 | |
| |
| Weighted average common shares outstanding: | | | | | | | | |
| Basic (in shares) | 28.2 | 27.7 | 27.8 | | 29.5 | | 29.5 | |
| Diluted (in shares) | 31.5 | 32.6 | 29.5 | | 30.7 | | 29.5 | |
| |
| Earnings (loss) per share: | | | | | | | | |
| Earnings Per Share, Basic (in dollars per share) | $2.47 | $10.42 | $7.54 | | $1.22 | | ($2.29) | |
| Earnings Per Share, Diluted (in dollars per share) | $2.21 | $8.85 | $7.10 | | $1.17 | | ($2.29) | |