XML 89 R78.htm IDEA: XBRL DOCUMENT
v3.20.4

Retirement Plans - Fair Value of Entity's Plan Assets (Details) - Pension Plan - USD ($) $ in Thousands | Dec. 25, 2020 | Mar. 27, 2020
--- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | $ 7,089 | $ 5,579
Level 1 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 3,031 | 2,467
Level 2 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 2,349 | 1,992
Level 3 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 1,709 | 1,120
Government securities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 1,826 | 1,260
Government securities | Level 1 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 1,826 | 1,260
Government securities | Level 2 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 0 | 0
Government securities | Level 3 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 0 | 0
Unit investment trust fund |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 1,155 | 897
Unit investment trust fund | Level 1 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 0 | 0
Unit investment trust fund | Level 2 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 1,155 | 897
Unit investment trust fund | Level 3 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 0 | 0
Loans |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 562 | 756
Loans | Level 1 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 0 | 0
Loans | Level 2 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 0 | 0
Loans | Level 3 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 562 | 756
Bonds |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 1,193 | 1,094
Bonds | Level 1 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 0 | 0
Bonds | Level 2 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 1,193 | 1,094
Bonds | Level 3 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 0 | 0
Stocks and other investments |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 2,353 | 1,572
Stocks and other investments | Level 1 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 1,205 | 1,207
Stocks and other investments | Level 2 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | 1 | 1
Stocks and other investments | Level 3 |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assets of non-U.S. defined benefit plan | $ 1,147 | $ 364

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/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + 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_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: |

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

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=algm_UnitInvestmentTrustFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_BankLoanObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CorporateBondSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DefinedBenefitPlanEquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |