Equity - Common Stock - Additional Information (Detail) - shares	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021
Amarin Corporation Plc 2017 Employee Stock Purchase Plan \| Ordinary Shares
Stockholders Equity Note [Line Items]
Issuance of common stock under employee stock purchase plan (in shares)	265,214	226,402

Number of shares issued during the period as a result of an employee stock purchase plan.

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Name:	us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration