Investments - Cash Equivalents and Investments held at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	$ 28,663	$ 30,066
Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	51,632	70,259
Fair Value, Measurements [Member] \| Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	33,558	52,364
Fair Value, Measurements [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	18,074	17,895
Money Market Funds [Member] \| Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	698	652
Money Market Funds [Member] \| Fair Value, Measurements [Member] \| Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	698	652
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	8,984	10,747
Corporate Bonds [Member] \| Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	8,984	10,747
Corporate Bonds [Member] \| Fair Value, Measurements [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	8,984	10,747
Municipal Fixed-Rate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	1,357	1,551
Municipal Fixed-Rate Bonds [Member] \| Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	1,357	1,551
Municipal Fixed-Rate Bonds [Member] \| Fair Value, Measurements [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	1,357	1,551
Asset-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	2,911	322
Asset-Backed Bonds [Member] \| Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	2,911	322
Asset-Backed Bonds [Member] \| Fair Value, Measurements [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	2,911	322
Mortgage/Agency-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	4,440	4,736
Mortgage/Agency-Backed Bonds [Member] \| Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	4,440	4,736
Mortgage/Agency-Backed Bonds [Member] \| Fair Value, Measurements [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	4,440	4,736
U.S. Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	10,589	12,171
U.S. Government Bonds [Member] \| Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	10,589	12,171
U.S. Government Bonds [Member] \| Fair Value, Measurements [Member] \| Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	10,589	12,171
Foreign Government Securities / Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	382	539
Foreign Government Securities / Bonds [Member] \| Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	382	539
Foreign Government Securities / Bonds [Member] \| Fair Value, Measurements [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	382	539
Marketable Equity Securities - Various Industries [Member] \| Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	760	12,606
Marketable Equity Securities - Various Industries [Member] \| Fair Value, Measurements [Member] \| Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	760	12,606
Deferred Compensation Plan Assets [Member] \| Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	21,511	26,935
Deferred Compensation Plan Assets [Member] \| Fair Value, Measurements [Member] \| Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	$ 21,511	$ 26,935

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

+ Details

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

No definition available.

+ Details

Name:	us-gaap_CashAndCashEquivalentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(2))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (f)
-URI https://asc.fasb.org/extlink&oid=124098289&loc=d3e6676-107765

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI https://asc.fasb.org/extlink&oid=123594786&loc=SL75136599-209740

+ Details

Name:	us-gaap_EquitySecuritiesFvNi
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CorporateBondSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MunicipalBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=adtn_MarketableEquitySecuritiesVariousIndustriesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=adtn_DeferredCompensationPlanAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: