Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Aug. 01, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Entity Registrant Name	ADTRAN INC
Trading Symbol	ADTN
Entity Central Index Key	0000926282
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		47,826,323
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	000-24612
Entity Tax Identification Number	630918200
Entity Address, Address Line One	901 Explorer Boulevard
Entity Address, City or Town	Huntsville
Entity Address, State or Province	Alabama
Entity Address, Postal Zip Code	35806-2807
City Area Code	(256)
Local Phone Number	963-8000