| Cover | Jan. 13, 2022 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jan. 13, 2022 |
| Current Fiscal Year End Date | --12-31 |
| Entity File Number | 001-39362 |
| Entity Registrant Name | Gelesis Holdings, Inc. |
| Entity Central Index Key | 0001805087 |
| Entity Tax Identification Number | 84-4730610 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 501 Boylston Street |
| Entity Address, Address Line Two | Suite 6102 |
| Entity Address, City or Town | Boston |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02116 |
| City Area Code | 617 |
| Local Phone Number | 456-4718 |
| 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 |
| Common Stock [Member] | |
| Title of 12(b) Security | Common Stock, par value $0.0001 per share |
| Trading Symbol | GLS |
| Security Exchange Name | NYSE |
| Redeemable warrants, each whole warrant exercisable for one share of Common Stock at an exercise price of $11.50 [Member] | |
| Title of 12(b) Security | Redeemable warrants, each whole warrant exercisable for one share of Common Stock at an exercise price of $11.50 |
| Trading Symbol | GLS WS |
| Security Exchange Name | NYSE |
