| Document And Entity Information | Oct. 30, 2019 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Oct. 30, 2019 |
| Entity Registrant Name | ADTRAN INC |
| Entity Central Index Key | 0000926282 |
| Entity Emerging Growth Company | false |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 000-24612 |
| Entity Tax Identification Number | 63-0918200 |
| Entity Address, Address Line One | 901 Explorer Boulevard |
| Entity Address, City or Town | Huntsville |
| Entity Address, State or Province | AL |
| Entity Address, Postal Zip Code | 35806-2807 |
| City Area Code | 256 |
| Local Phone Number | 963-8000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of each class | Common Stock, Par Value $0.01 |
| Trading Symbol | ADTN |
| Name of exchange on which registered | NASDAQ |
