| Document And Entity Information | Nov. 20, 2023 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 20, 2023 |
| Entity Registrant Name | KLDiscovery Inc. |
| Entity Central Index Key | 0001752474 |
| Entity Emerging Growth Company | true |
| Entity File Number | 001-38789 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 61-1898603 |
| Entity Address, Address Line One | 9023 Columbine Road |
| Entity Address, City or Town | Eden Prairie |
| Entity Address, State or Province | MN |
| Entity Address, Postal Zip Code | 55347 |
| City Area Code | 703 |
| Local Phone Number | 288-3380 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Ex Transition Period | false |
| Title of 12(b) Security | N/A |
| No Trading Symbol Flag | true |
| Security Exchange Name | NONE |
