Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Payables and Accruals [Abstract]
Accrued external research and development	$ 6,216	$ 5,355
Accrued employee compensation and benefits	5,625	10,055
Accrued consulting and other professional fees	2,556	1,855
Other accrued expenses	212	645
Total accrued expenses	$ 14,609	$ 17,910

Accrued consulting and other professional fess.

No definition available.

Name:	amlx_AccruedConsultingAndOtherProfessionalFess
Namespace Prefix:	amlx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Accrued external research and development.

+ References

No definition available.

+ Details

Name:	amlx_AccruedExternalResearchAndDevelopmentCurrent
Namespace Prefix:	amlx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of expenses incurred but not yet paid nor invoiced, and liabilities classified as other.

+ References

No definition available.

+ Details

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

- Definition

Total of the carrying values as of the balance sheet date of obligations incurred through that date and payable for obligations related to services received from employees, such as accrued salaries and bonuses, payroll taxes and fringe benefits. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(20))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

+ Details

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

- Definition

Amount of expenses incurred but not yet paid classified as other, due within one year or the normal operating cycle, if longer.

+ References

+ Details

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

- References

No definition available.

+ Details

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