Annual Total Returns |
12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| ARBITRAGE FUND | Class R | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 8.01% | 2.62% | 5.94% | (1.02%) | 0.85% | 5.43% | 3.56% | 2.12% | 2.60% | 3.38% |
| WATER ISLAND EVENT-DRIVEN FUND | Class R | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 8.41% | 1.91% | 5.63% | (0.82%) | 0.91% | 13.02% | 4.52% | (0.34%) | 3.68% | 5.06% |
| WATER ISLAND CREDIT OPPORTUNITIES FUND | Class R | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 4.62% | 5.23% | 7.01% | (2.93%) | 3.06% | 6.41% | 5.28% | 1.69% | 1.16% | 4.72% |
| ALTSHARES MERGER ARBITRAGE ETF | AltShares Merger Arbitrage ETF | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 5.58% | 4.04% | 4.04% | 2.59% | 3.20% | |||||
| ALTSHARES EVENT-DRIVEN ETF | AltShares Event-Driven ETF | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 13.57% | 5.69% | 13.21% | (9.04%) | (2.58%) | 43.45% | 6.92% | (4.70%) | 5.84% | 4.58% |