Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 17, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Trading Symbol	LDL
Entity Common Stock, Shares Outstanding		17,241,883
Entity Registrant Name	LYDALL INC /DE/
Entity Central Index Key	0000060977
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer