Debt instrument amortization rate.

No definition available.

Name:	algm_DebtInstrumentAmortizationRate
Namespace Prefix:	algm_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Covenant, Leverage Ratio, Maximum

+ References

No definition available.

+ Details

Name:	algm_DebtInstrumentCovenantLeverageRatioMaximum
Namespace Prefix:	algm_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument Loans and Commitments Terminate Percentage

+ References

No definition available.

+ Details

Name:	algm_DebtInstrumentLoansAndCommitmentsTerminatePercentage
Namespace Prefix:	algm_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Payments to term loan.

+ References

No definition available.

+ Details

Name:	algm_PaymentsToTermLoan
Namespace Prefix:	algm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 30
-Paragraph 8
-SubTopic 30
-Topic 805
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479637/805-30-30-8

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-SubTopic 30
-Topic 805
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 30
-Paragraph 7
-SubTopic 30
-Topic 805
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479637/805-30-30-7

+ Details

Name:	us-gaap_BusinessCombinationConsiderationTransferred1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the fee that accompanies borrowing money under the debt instrument.

+ References

+ Details

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

- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22)(a)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482925/835-30-45-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482900/835-30-50-1

+ Details

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

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-SubTopic 10
-Topic 210
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16)(a)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481544/470-10-50-6

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481544/470-10-50-6

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(f))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LetterOfCreditMember
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:	us-gaap_VariableRateAxis=us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember
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_DebtInstrumentAxis=algm_TwoThousandTwentyThreeTermLoanFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=algm_TwoThousandTwentyTermLoanFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=algm_CreditSuisseAGCaymanIslandsBranchMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=algm_RefinancedAndRepricingTwoThousandTwentyFiveTermLoanFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_FederalFundsEffectiveSwapRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=algm_OneMonthSecuredOvernightFinancingRateSOFROvernightIndexSwapRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=algm_MorganStanleySeniorFundingIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=algm_RefinancedTwoThousandAndTwentyFourTermLoanFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=algm_TermLoanFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt and Other Borrowings - Additional Information (Details)									12 Months Ended
	Apr. 30, 2025 USD ($)	Feb. 28, 2025 USD ($)	Feb. 06, 2025 USD ($)	Oct. 31, 2024 USD ($)	Aug. 06, 2024 USD ($)	Apr. 30, 2024 USD ($)	Oct. 31, 2023 USD ($)	Jun. 21, 2023 USD ($)	Mar. 28, 2025 USD ($)
Line of Credit Facility [Line Items]
Preliminary purchase price									$ 6,000,000
Letter of Credit \| Minimum \| SOFR
Line of Credit Facility [Line Items]
Basis spread on variable rate									1.50%
Letter of Credit \| Maximum \| SOFR
Line of Credit Facility [Line Items]
Basis spread on variable rate									1.75%
2023 Term Loan Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity							$ 250,000,000
2020 Term Loan Facility \| Credit Suisse AG, Cayman Islands Branch
Line of Credit Facility [Line Items]
Outstanding balance							$ 25,000,000
Refinanced and Repricing 2025 Term Loan Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity			$ 375,000,000
Amortization rate per quarter			0.00%
Maturity date			Oct. 31, 2030
Incurred fees amount			$ 1,090,000
Payment applied to the term loan balance	$ 25,000,000	$ 30,000,000
Refinanced and Repricing 2025 Term Loan Facility \| SOFR
Line of Credit Facility [Line Items]
Basis spread on variable rate			2.00%
Refinanced and Repricing 2025 Term Loan Facility \| Fed Fund Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.50%
Refinanced and Repricing 2025 Term Loan Facility \| One- Month SOFR
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.00%
Refinanced and Repricing 2025 Term Loan Facility \| Maximum \| One- Month SOFR
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.00%
Senior Secured Revolving Credit Facility
Line of Credit Facility [Line Items]
Leverage ratio									0.045
Senior Secured Revolving Credit Facility \| Morgan Stanley Senior Funding, Inc
Line of Credit Facility [Line Items]
Maximum borrowing capacity					$ 256,000,000			$ 224,000,000
Maturity date								Jun. 21, 2028
Outstanding balance									$ 0
Senior Secured Revolving Credit Facility \| Letter of Credit
Line of Credit Facility [Line Items]
Leverage ratio									0.04
Preliminary purchase price									$ 500,000,000
Terminate percentage									0.50
Senior Secured Revolving Credit Facility \| Letter of Credit \| Fed Fund Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate									0.50%
Senior Secured Revolving Credit Facility \| Letter of Credit \| One- Month SOFR
Line of Credit Facility [Line Items]
Basis spread on variable rate									1.00%
Senior Secured Revolving Credit Facility \| Letter of Credit \| Minimum
Line of Credit Facility [Line Items]
Commitment fee percentage									0.20%
Senior Secured Revolving Credit Facility \| Letter of Credit \| Minimum \| One- Month SOFR
Line of Credit Facility [Line Items]
Basis spread on variable rate									0.50%
Senior Secured Revolving Credit Facility \| Letter of Credit \| Maximum
Line of Credit Facility [Line Items]
Commitment fee percentage									0.25%
Senior Secured Revolving Credit Facility \| Letter of Credit \| Maximum \| One- Month SOFR
Line of Credit Facility [Line Items]
Basis spread on variable rate									0.75%
Senior Secured Revolving Credit Facility \| Letter of Credit \| Morgan Stanley Senior Funding, Inc
Line of Credit Facility [Line Items]
Maximum borrowing capacity								$ 20,000,000
Refinanced 2024 Term Loan Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity					$ 400,000,000
Amortization rate per quarter					1.00%
Maturity date					Oct. 31, 2030
Payment applied to the term loan balance				$ 25,000,000
Debt issuance costs recognized					$ 3,619,000
Refinanced 2024 Term Loan Facility \| SOFR
Line of Credit Facility [Line Items]
Basis spread on variable rate					2.25%
Refinanced 2024 Term Loan Facility \| Fed Fund Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate					0.50%
Refinanced 2024 Term Loan Facility \| One- Month SOFR
Line of Credit Facility [Line Items]
Basis spread on variable rate					1.00%
Refinanced 2024 Term Loan Facility \| Maximum \| One- Month SOFR
Line of Credit Facility [Line Items]
Basis spread on variable rate					1.25%
Term Loan Facility
Line of Credit Facility [Line Items]
Amortization rate per quarter							0.25%
Payment applied to the term loan balance						$ 50,000,000
Term Loan Facility \| SOFR
Line of Credit Facility [Line Items]
Basis spread on variable rate							2.75%
Term Loan Facility \| Base Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate							1.75%