Co-Promotion Agreement - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Co Promotion Agreement [Line Items]
Accrued expenses and other current liabilities	$ 214,598	$ 192,678

Accrued liabilities and other liabilities current.

No definition available.

Name:	amrn_AccruedLiabilitiesAndOtherLiabilitiesCurrent
Namespace Prefix:	amrn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant