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Deferred Tax Liabilities, Subject to Expiration

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- Definition

Employee service share based compensation tax benefit (deficiency) realized from exercise of stock options.

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Income tax.

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Statutory Tax Rate

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Tax credit carryforward expiration year.

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- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible foreign operating loss carryforwards.

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Amount, before allocation of a valuation allowances, of deferred tax assets attributable to deductible tax credit carryforwards including, but not limited to, research, foreign, general business, alternative minimum tax, and other deductible tax credit carryforwards.

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Amount of deferred tax liability not recognized because of the exceptions to comprehensive recognition of deferred taxes related to undistributed earnings of foreign subsidiaries.

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Amount of undistributed earnings of foreign subsidiaries intended to be permanently reinvested outside the country of domicile.

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Amount of expense for penalties related to a tax position claimed or expected to be claimed in the tax return.

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Amount of interest expense for an underpayment of income taxes.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Taxes [Line Items]
Total amount of unrecognized tax benefits that would affect the tax rate if recognized	$ 11,700,000	$ 8,900,000
Interest related to uncertain tax positions	1,700,000	700,000
Penalties related to uncertain tax positions	0	0
Gross liabilities to expire in 2024	0
Decrease in net operating loss carryforwards from prior years	75,600,000
Tax credit carryforwards	2,421,000	2,409,000
Undistributed earning retained indefinitely for reinvestment by foreign subsidiary	0
Unrecognized deferred income tax liability	0
ASU No. 2016-09
Income Taxes [Line Items]
Provisions benefit for income taxes	$ 1,000,000	$ 0	$ 600,000
Ireland
Income Taxes [Line Items]
Corporate tax rate	25.00%	25.00%	25.00%
Ireland \| Amarin Pharmaceuticals Ireland Limited
Income Taxes [Line Items]
Corporate tax rate	12.50%	12.50%	12.50%
Ireland \| Non-Trading Activity
Income Taxes [Line Items]
Corporate tax rate	25.00%
Ireland \| Trading Activity
Income Taxes [Line Items]
Corporate tax rate	12.50%
U.S. and Non-U.S.
Income Taxes [Line Items]
Foreign net operating loss carryforwards	$ 1,000,000,000
U.S. Federal
Income Taxes [Line Items]
Tax credit carryforwards	7,800,000
State
Income Taxes [Line Items]
Tax credit carryforwards	$ 4,100,000
State \| Minimum
Income Taxes [Line Items]
Tax credit carryforward expiration year	2025
State \| Maximum
Income Taxes [Line Items]
Tax credit carryforward expiration year	2044