| Cover Page | Oct. 29, 2019 |
| Cover page. | |
| Amendment Flag | false |
| Entity Central Index Key | 0000060977 |
| Document Type | 8-K |
| Document Period End Date | Oct. 29, 2019 |
| Entity Registrant Name | LYDALL INC /DE/ |
| Entity File Number | 1-7665 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 06-0865505 |
| Entity Address, Address Line One | One Colonial Road |
| Entity Address, City or Town | Manchester |
| Entity Address, State or Province | CT |
| Entity Address, Postal Zip Code | 06042 |
| City Area Code | 860 |
| Local Phone Number | 646-1233 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.01 par value |
| Trading Symbol | LDL |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
