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Employee Benefit Plans (Deferred Compensation Plans) - Additional Information (Detail) $ in Millions | 12 Months Ended
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Dec. 31, 2019 USD ($) Compensation_Program | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
Compensation And Retirement Disclosure [Abstract] |  |  |
Number of deferred compensation programs | Compensation_Program | 4 |  |
Maximum percentage of cash compensation allowed to be deferred under the deferred compensation plan | 25.00% |  |
Criteria for benefit distribution | six months after termination of employment in a single lump sum payment or annual installments paid over a three or ten-year term based on the participant’s election |  |
Deferred compensation income (expense) adjustments due to fair value of the trust assets | $ | $ 3.6 | $ (2.1) | $ (2.6)

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- Definition Distribution schedule for deferred compensation plan benefits. + References No definition available. + Details
Name: | adtn_CriteriaForBenefitDistribution
Namespace Prefix: | adtn_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Amounts recognized in selling, general and administrative expense due to changes in the fair value of the deferred compensation plan liability. + References No definition available. + Details
Name: | adtn_DeferredCompensationAdjustmentsDueToFairValueOfTrustAssets
Namespace Prefix: | adtn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition The maximum percentage of cash compensation that is allowed to be deferred under the deferred compensation plan. + References No definition available. + Details
Name: | adtn_MaximumPercentageOfCashCompensationAllowedToBeDeferredUnderDeferredCompensationPlan
Namespace Prefix: | adtn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Definition Number of deferred compensation programs. + References No definition available. + Details
Name: | adtn_NumberOfDeferredCompensationPrograms
Namespace Prefix: | adtn_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_CompensationAndRetirementDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration