| Cover | Jan. 29, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jan. 29, 2021 |
| Entity File Number | 001-37721 |
| Entity Registrant Name | ACACIA RESEARCH CORPORATION |
| Entity Central Index Key | 0000934549 |
| Entity Tax Identification Number | 95-4405754 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 4 Park Plaza |
| Entity Address, Address Line Two | Suite 550 |
| Entity Address, City or Town | Irvine |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 92614 |
| City Area Code | (949) |
| Local Phone Number | 480-8300 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.001 par value per share |
| Trading Symbol | ACTG |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Information, Former Legal or Registered Name | Not applicable |
