| Cover | Feb. 28, 2025 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Feb. 28, 2025 |
| Current Fiscal Year End Date | --12-31 |
| Entity File Number | 811-21969 |
| Entity Registrant Name | The GDL Fund |
| Entity Central Index Key | 0001378701 |
| Entity Tax Identification Number | 20-8195443 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | One Corporate Center |
| Entity Address, City or Town | Rye |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10580-1422 |
| City Area Code | 800 |
| Local Phone Number | 422-3554 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Shares of Beneficial Interest | |
| Title of 12(b) Security | Common Shares of Beneficial Interest |
| Trading Symbol | GDL |
| Security Exchange Name | NYSE |
| Series C Cumulative Puttable and Callable Preferred Shares | |
| Title of 12(b) Security | Series C Cumulative Puttable and Callable Preferred Shares |
| Trading Symbol | GDL Pr C |
| Security Exchange Name | NYSE |
