Leases - Additional Information (Detail) $ in Thousands			3 Months Ended
	Feb. 01, 2022 USD ($) RenewalOption	Aug. 15, 2019 USD ($) RenewalOption	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2021 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			$ 17,383
Operating lease liability			11,300		$ 10,300
Operating lease right-of-use asset			8,689		$ 7,660
Operating lease expense			$ 600	$ 400
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 New Jersey Commencement Date upon advance written notice and a termination payment specified in the New Jersey Lease.
Lease termination description			one-time option to terminate the agreement effective on the first day of the 97th month after the New Jersey Commencement Date
Lease termination existence of option to extend		true
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
Maximum
Lessee Lease Description [Line Items]
Short term lease period			12 months
Maximum | Vehicles
Lessee Lease Description [Line Items]
Lease agreement term			36 months