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

Equity - Common Stock - Additional Information (Detail) € in Millions		9 Months Ended
	Jul. 13, 2022 EUR (€) shares	Sep. 30, 2022 shares	Sep. 30, 2021 shares	Jul. 13, 2022 $ / shares
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
Food and Drug Administration
Stockholders Equity Note [Line Items]
Milestone payment \| €	€ 7.5
Stock issuance of shares	5,817,942
Sale of stock per share \| $ / shares				$ 1.41