XML 132 R122.htm IDEA: XBRL DOCUMENT v3.24.0.1

Employee Benefit Plans (Pension Benefit Plan) - Schedule of Cash Equivalents and Investments Held at Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 55,218	$ 48,720
Pension Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	55,218	48,720
Pension Benefit Plan [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,144
Pension Benefit Plan [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	987	1,423
Pension Benefit Plan [Member] | Available-For-Sale Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	54,231	47,297
Pension Benefit Plan [Member] | Bond Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	20,155
Pension Benefit Plan [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21,525
Pension Benefit Plan [Member] | Other Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,054
Pension Benefit Plan [Member] | Insuarance Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	353
Pension Benefit Plan [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		13,256
Pension Benefit Plan [Member] | Government Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		5,490
Pension Benefit Plan [Member] | Global Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		15,452
Pension Benefit Plan [Member] | Balanced Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		5,190
Pension Benefit Plan [Member] | Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,707
Pension Benefit Plan [Member] | Large Cap Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		194
Pension Benefit Plan [Member] | Global Real Estate Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		6,008
Pension Benefit Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	47,004	40,521
Pension Benefit Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	546
Pension Benefit Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	987	1,423
Pension Benefit Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Available-For-Sale Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	46,017	39,098
Pension Benefit Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Bond Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18,840
Pension Benefit Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21,288
Pension Benefit Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,343
Pension Benefit Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		11,667
Pension Benefit Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Government Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		5,490
Pension Benefit Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Global Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		15,150
Pension Benefit Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Balanced Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		4,148
Pension Benefit Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,707
Pension Benefit Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Large Cap Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		194
Pension Benefit Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Global Real Estate Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		742
Pension Benefit Plan [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,942	4,510
Pension Benefit Plan [Member] | Significant Other Observable Inputs (Level 2) [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,326
Pension Benefit Plan [Member] | Significant Other Observable Inputs (Level 2) [Member] | Available-For-Sale Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,942	4,510
Pension Benefit Plan [Member] | Significant Other Observable Inputs (Level 2) [Member] | Bond Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,315
Pension Benefit Plan [Member] | Significant Other Observable Inputs (Level 2) [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	237
Pension Benefit Plan [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	711
Pension Benefit Plan [Member] | Significant Other Observable Inputs (Level 2) [Member] | Insuarance Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	353
Pension Benefit Plan [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,590
Pension Benefit Plan [Member] | Significant Other Observable Inputs (Level 2) [Member] | Global Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		301
Pension Benefit Plan [Member] | Significant Other Observable Inputs (Level 2) [Member] | Balanced Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,042
Pension Benefit Plan [Member] | Significant Other Observable Inputs (Level 2) [Member] | Global Real Estate Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,577
Pension Benefit Plan [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,272	3,689
Pension Benefit Plan [Member] | Significant Unobservable Inputs (Level 3) [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,272
Pension Benefit Plan [Member] | Significant Unobservable Inputs (Level 3) [Member] | Available-For-Sale Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 3,272	3,689
Pension Benefit Plan [Member] | Significant Unobservable Inputs (Level 3) [Member] | Global Real Estate Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 3,689

X

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

X

- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480482/715-20-55-17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(02)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(ii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(01)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(ii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(01)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

+ Details

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

X

- Details

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

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

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DefinedBenefitPlanCashAndCashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=adtn_DefinedBenefitPlanAvailableForSaleSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=adtn_BondFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_EquityFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=adtn_OtherFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=adtn_InsuranceContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

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

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DefinedBenefitPlanEquitySecuritiesNonUsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=adtn_DefinedBenefitPlanEquitySecuritiesBalancedFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=adtn_DefinedBenefitPlanEquitySecuritiesEmergingMarketsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DefinedBenefitPlanEquitySecuritiesLargeCapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=adtn_GlobalRealEstateFundMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

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

X

- Details

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

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: