Development, Commercialization and Supply Agreement - Additional Information (Detail)		1 Months Ended														3 Months Ended		6 Months Ended		12 Months Ended
		Jun. 30, 2025 USD ($)	Feb. 28, 2025 USD ($)	Oct. 31, 2024 USD ($)	Jun. 30, 2024 USD ($)	Jan. 31, 2024 USD ($)	Oct. 31, 2023 USD ($)	Feb. 28, 2023 USD ($)	Jan. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Feb. 28, 2015 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) Country	Jun. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2023 USD ($)
License And Collaboration Agreements [Line Items]
Revenue recognized related to upfront and milestone payments																	$ 4,900,000
Revenue recognized related to upfront and milestone payments																		$ 0	$ 4,850,000
Licenses revenue																$ 72,741,000	67,491,000	114,757,000	124,010,000
Deferred revenue		$ 0			$ 0											0	0	0	0	$ 0		$ 4,850,000
Product Revenue, Net
License And Collaboration Agreements [Line Items]
Licenses revenue																46,617,000	47,514,000	87,652,000	102,670,000
Mochida Pharmaceutical Co., Ltd. | In-licenses
License And Collaboration Agreements [Line Items]
Milestones payment			$ 1,000,000			$ 1,000,000
Mochida Pharmaceutical Co., Ltd. | In-licenses | Research and Development Expense
License And Collaboration Agreements [Line Items]
Up-front payment																					$ 2,700,000
Edding
License And Collaboration Agreements [Line Items]
Revenue recognized related to upfront and milestone payments																	4,000,000
Edding | Achievement of REDUCE-IT Trial | VASCEPA
License And Collaboration Agreements [Line Items]
Non-refundable milestone payment received					$ 15,000,000
Edding | Out-licenses
License And Collaboration Agreements [Line Items]
Non-refundable up-front received															$ 15,000,000
Sales-based milestone event payment		120,000,000														120,000,000		120,000,000
Revenue recognized related to upfront and milestone payments	[1]																		19,450,000
Revenue recognized related to upfront and milestone payments	[1]																	0
Edding | Out-licenses | Licensing Revenue
License And Collaboration Agreements [Line Items]
Licenses revenue																		40,081,000		$ 40,081,000
Edding | Out-licenses | Product Revenue, Net
License And Collaboration Agreements [Line Items]
Licenses revenue																0	100,000	0	3,400,000
Edding | Out-licenses | Maximum
License And Collaboration Agreements [Line Items]
Sales-based milestone event payment		50,000,000														50,000,000		50,000,000
Edding | Out-licenses | Minimum
License And Collaboration Agreements [Line Items]
Sales-based milestone event payment		5,000,000														5,000,000		5,000,000
Edding | Out-licenses | Clinical Trial Application
License And Collaboration Agreements [Line Items]
Non-refundable milestone payment received														$ 1,000,000
Edding | Out-licenses | Achievement of REDUCE-IT Trial
License And Collaboration Agreements [Line Items]
Non-refundable milestone payment received							$ 3,000,000
Edding | Out-licenses | Marine
License And Collaboration Agreements [Line Items]
Additional license revenues		4,000,000														4,000,000		4,000,000
Revenue recognized related to upfront and milestone payments																	15,000,000
Reduction in net loss																		4,000,000
Edding | Out-licenses | Marine | VASCEPA
License And Collaboration Agreements [Line Items]
Non-refundable milestone payment received													$ 5,000,000
Biologix FZCo | Out-licenses | Product Revenue, Net
License And Collaboration Agreements [Line Items]
Licenses revenue																2,800,000	0	2,700,000	0
HLS | Out-licenses
License And Collaboration Agreements [Line Items]
Non-refundable up-front received												$ 5,000,000
Non-refundable milestone payment received									$ 3,800,000
HLS | Out-licenses | Health Canada
License And Collaboration Agreements [Line Items]
Non-refundable milestone payment received										$ 2,500,000
HLS | Out-licenses | Product Revenue, Net
License And Collaboration Agreements [Line Items]
Licenses revenue																0	0	0	1,900,000
HLS | Out-licenses | Maximum
License And Collaboration Agreements [Line Items]
Additional upfront payment eligible to receive based on development, regulatory and sales Milestone												$ 50,000,000
HLS | Out-licenses | Achievement of REDUCE-IT Trial
License And Collaboration Agreements [Line Items]
Non-refundable milestone payment received											$ 2,500,000
CSL Seqirus | Out-licenses
License And Collaboration Agreements [Line Items]
Non-refundable up-front received								$ 500,000
Non-refundable milestone payment received				$ 1,200,000
Upfront payment receivable								500,000
Event-related milestone payments receivable								6,000,000
Additional product-related milestone payments receivable								$ 4,000,000
CSL Seqirus | Out-licenses | Product Revenue, Net
License And Collaboration Agreements [Line Items]
Licenses revenue																800,000	0	$ 800,000	0
Recordati Industria Chimica e Farmaceutica S.p.A.
License And Collaboration Agreements [Line Items]
Number of countries | Country																		59
Recordati Industria Chimica e Farmaceutica S.p.A. | Out-licenses
License And Collaboration Agreements [Line Items]
Up-front payment																25,000,000
Non-refundable up-front received		25,000,000
Recordati Industria Chimica e Farmaceutica S.p.A. | Out-licenses | Product Revenue, Net
License And Collaboration Agreements [Line Items]
Licenses revenue																$ 25,000,000	$ 0	$ 25,000,000	$ 0
Recordati Industria Chimica e Farmaceutica S.p.A. | Out-licenses | Maximum
License And Collaboration Agreements [Line Items]
Milestones payment		$ 150,000,000

[1] Licensing revenue under the DCS Agreement is recognized concurrent with the input measure of support hours provided by Amarin to Edding in achieving the combined development and regulatory performance obligation, which in the Company’s judgment is the best measure of progress towards satisfying this performance obligation.