Stock-Based Compensation (Stock Incentive Program Descriptions) - Additional Information (Detail) - shares	12 Months Ended
Dec. 31, 2020	Jan. 31, 2015
PSUs, RSUs and Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	4 years
2015 Employee Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of additional shares of common stock granted	0
Number of shares of common stock authorized		7,700,000
Multiplier used when issuing PSUs, restricted stock and RSUs		2.5
Vesting period	4 years
Contractual term	10 years
2015 Employee Stock Incentive Plan [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration date of options	2025
2015 Employee Stock Incentive Plan [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration date of options	2026
2010 Directors Stock Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of additional shares of common stock granted	0
Number of shares of common stock authorized	500,000
Contractual term	10 years
Expiration date of options	2019
Previous Stock Incentive Plans [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of additional shares of common stock granted	0
2020 Employee Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock authorized	2,800,000
Multiplier used when issuing PSUs, restricted stock and RSUs	1
Contractual term	10 years
2020 Employee Incentive Plan [Member] \| PSUs, RSUs and Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	4 years
2020 Employee Incentive Plan [Member] \| Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	4 years
2015 Employee Incentive Plan to 2020 Employee Incentive Plan [Member] \| PSUs, RSUs and Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Forfeiture of stock increase in issuance of common stock	2.5
2020 Directors Stock Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock authorized	400,000
Multiplier used when issuing PSUs, restricted stock and RSUs	1
Forfeiture of stock increase in issuance of common stock	1
Contractual term	10 years
2006 Employee Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock authorized	13,000,000.0
Vesting period	4 years
Contractual term	10 years
2006 Employee Stock Incentive Plan [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration date of options	2021
2006 Employee Stock Incentive Plan [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration date of options	2024

Year the equity-based award expires.

No definition available.

Name:	adtn_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpirationYear
Namespace Prefix:	adtn_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Share based compensation arrangement by share based payment award forfeiture of common stock multiplier used in determining issuable shares.

+ References

No definition available.

+ Details

Name:	adtn_ShareBasedCompensationArrangementByShareBasedPaymentAwardForfeitureOfCommonStockMultiplierUsedInDeterminingIssuableShares
Namespace Prefix:	adtn_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Share based compensation arrangement by share based payment award number of additional shares granted.

+ References

No definition available.

+ Details

Name:	adtn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesGranted
Namespace Prefix:	adtn_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based compensation arrangement by share-based payment award, common stock multiplier used in determining issuable shares.

+ References

No definition available.

+ Details

Name:	adtn_SharebasedCompensationArrangementBySharebasedPaymentAwardCommonStockMultiplierUsedInDeterminingIssuableShares
Namespace Prefix:	adtn_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares authorized for issuance under share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=adtn_TwoThousandAndFifteenEmployeeStockIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=adtn_TwoThousandAndTenDirectorsStockPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=adtn_PreviousStockIncentivePlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=adtn_TwoThousandTwentyEmployeeIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=adtn_TwoThousandAndFifteenToTwoThousandTwentyEmployeeIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=adtn_TwoThousandTwentyDirectorsStockPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=adtn_TwoThousandAndSixEmployeeStockIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: