Leases - Additional Information (Detail) $ in Thousands					12 Months Ended
	Feb. 01, 2023 USD ($)	Oct. 01, 2022 USD ($)	Feb. 01, 2022 USD ($) RenewalOption	Aug. 15, 2019 USD ($) RenewalOption	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Lessee Lease Description [Line Items]
Incremental borrowing rate for purposes of calculation of lease liabilities					11.50%
Change in incremental borrowing rate					1.00%
Rent payment					$ 16,808
Operating lease liability					11,600	$ 10,300
Operating lease right-of-use asset					9,074	7,660
Operating lease expense					$ 2,800	$ 2,200	$ 1,600
Bridgewater
Lessee Lease Description [Line Items]
Lease commencement date				Aug. 15, 2019
Lease agreement term				11 years
Number of renewal options | RenewalOption				2
Lease renewal term				5 years
Description of lease agreement					Amarin will have a one-time option to terminate the agreement effective on the first day of the 97th month after the Commencement Date upon advance written notice and a termination payment specified in the Lease.
Lease termination description					one-time option to terminate the agreement effective on the first day of the 97th month after the Commencement Date
Lease termination existence of option to extend				true
Rent payment				$ 100
Bridgewater | Subsequent Event
Lessee Lease Description [Line Items]
Sublease commencement date	Feb. 01, 2023
Lease agreement term	7 years 6 months
Receive rent payment	$ 100
Zug Switzerland
Lessee Lease Description [Line Items]
Lease commencement date			Feb. 01, 2022
Lease agreement term			5 years
Number of renewal options | RenewalOption			1
Lease renewal term			5 years
Rent payment			$ 200
Dublin
Lessee Lease Description [Line Items]
Lease commencement date		Oct. 01, 2022
Lease agreement term		2 years
Rent payment		$ 400
Maximum
Lessee Lease Description [Line Items]
Short term lease period					12 months
Maximum | Vehicles
Lessee Lease Description [Line Items]
Lease agreement term					36 months