XML 39 R31.htm IDEA: XBRL DOCUMENT
v3.26.1

Collaboration Agreement with GSK - Additional Information (Details) $ in Thousands |  |  |  | 1 Months Ended | 3 Months Ended | 6 Months Ended |
--- | --- | --- | --- | --- | --- | --- | ---
Jul. 06, 2026 | Aug. 17, 2021 USD ($) | Jul. 01, 2021 USD ($) | May 31, 2023 USD ($) | Jan. 31, 2022 USD ($) | Jun. 30, 2026 USD ($) | Jun. 30, 2025 USD ($) | Jun. 30, 2026 USD ($) | Jun. 30, 2025 USD ($) | Dec. 31, 2025 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |
Research and development expense |  |  |  |  |  | $ 19,460 | $ 27,611 | $ 37,317 | $ 61,252 |
Subsequent Event |  |  |  |  |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |
Agreement termination date | Jan. 02, 2027 |  |  |  |  |  |  |  |  |
GlaxoSmithKline plc |  |  |  |  |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |
Effective date of agreement |  | Aug. 17, 2021 |  |  |  |  |  |  |  |
Upfront payments |  |  | $ 700,000 |  |  |  |  | $ 700,000 |  |
Milestone payment received |  | $ 500,000 |  |  | $ 200,000 |  |  |  |  |
Percentage Of Development Cost |  |  |  |  |  |  |  | 0.60 |  |
Collaboration revenue |  |  |  |  |  | 3,300 | 7,900 | $ 4,400 | 11,500 |
Deferred revenue |  |  |  |  |  | 162,900 |  | 162,900 |  | $ 171,200
Research and development expense |  |  |  |  |  | 300 | $ 6,100 | 1,500 | $ 10,400 |
Transaction price |  |  |  |  |  | 564,000 |  | 564,000 |  |
Contract with customer, refund liability |  |  |  |  |  | 0 |  | 0 |  | $ 11,400
Maximum funding |  |  |  | $ 140,500 |  |  |  |  |  |
GlaxoSmithKline plc | Maximum |  |  |  |  |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |
Additional milestone payments related to initiation of certain clinical studies and regulatory approval |  |  |  |  |  | $ 1,500,000 |  | $ 1,500,000 |  |
Alector |  |  |  |  |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |
Percentage Of Development Cost |  |  |  |  |  |  |  | 0.40 |  |

X
- Definition Collaboration and License Agreement Effective Date + References No definition available. + Details
Name: | alec_CollaborationAndLicenseAgreementEffectiveDate
Namespace Prefix: | alec_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Collaborative arrangement, additional milestone payments receivable. + References No definition available. + Details
Name: | alec_CollaborativeArrangementAdditionalMilestonePaymentsReceivable
Namespace Prefix: | alec_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Collaborative arrangement, upfront payments. + References No definition available. + Details
Name: | alec_CollaborativeArrangementUpfrontPayments
Namespace Prefix: | alec_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Company maximum funding. + References No definition available. + Details
Name: | alec_CompanyMaximumFunding
Namespace Prefix: | alec_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Contract termination date. + References No definition available. + Details
Name: | alec_ContractTerminationDate
Namespace Prefix: | alec_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of development cost. + References No definition available. + Details
Name: | alec_PercentageOfDevelopmentCost
Namespace Prefix: | alec_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Transactions Price. + References No definition available. + Details
Name: | alec_TransactionsPrice
Namespace Prefix: | alec_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 808 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479402/808-10-50-1 + Details
Name: | us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-11 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479837/606-10-45-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-8 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479837/606-10-45-2 + Details
Name: | us-gaap_ContractWithCustomerLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-8 + Details
Name: | us-gaap_ContractWithCustomerLiabilityRevenueRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of liability for consideration received or receivable from customer which is not included in transaction price, when consideration is expected to be refunded to customer. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 27 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479777/606-10-55-27 + Details
Name: | us-gaap_ContractWithCustomerRefundLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Cash received from collaborators during the current period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 25 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-25 + Details
Name: | us-gaap_ProceedsFromCollaborators
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of expense for research and development. Includes, but is not limited to, cost for computer software product to be sold, leased, or otherwise marketed and writeoff of research and development assets acquired in transaction other than business combination or joint venture formation or both. Excludes write-down of intangible asset acquired in business combination or from joint venture formation or both, used in research and development activity. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 18 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-18 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-14 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 48 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482785/280-10-55-48 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 985 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481283/985-20-50-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 730 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482916/730-10-50-1 Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 912 -SubTopic 730 -Name Accounting Standards Codification -Section 25 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479532/912-730-25-1 + Details
Name: | us-gaap_ResearchAndDevelopmentExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=alec_GskMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=alec_AlectorMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |