| Cover | Oct. 22, 2021 |
| Entity Addresses [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Oct. 22, 2021 |
| Current Fiscal Year End Date | --12-31 |
| Entity File Number | 001-39741 |
| Entity Registrant Name | REDBOX ENTERTAINMENT INC. |
| Entity Central Index Key | 0001820201 |
| Entity Tax Identification Number | 85-2157010 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 1 Tower Lane, Suite 800 |
| Entity Address, City or Town | Oakbrook Terrace |
| Entity Address, State or Province | IL |
| Entity Address, Postal Zip Code | 60181 |
| City Area Code | 212 |
| Local Phone Number | 616-7700 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |
| Entity Information, Former Legal or Registered Name | Seaport Global Acquisition Corp. |
| Common Class A [Member] | |
| Entity Addresses [Line Items] | |
| Title of 12(b) Security | Class A common stock, par value $0.0001 per share |
| Trading Symbol | RDBX |
| Security Exchange Name | NASDAQ |
| Warrant [Member] | |
| Entity Addresses [Line Items] | |
| Title of 12(b) Security | Warrants to purchase Class A common stock |
| Trading Symbol | RDBXW |
| Security Exchange Name | NASDAQ |
| Former Address [Member] | |
| Entity Addresses [Line Items] | |
| Entity Address, Address Line One | 360 Madison Avenue |
| Entity Address, Address Line Two | 20th Floor |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10017 |
