Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revenues [Abstract]
Revenue	$ 188,411	$ 133,791	$ 318,935	$ 275,710
Commercial Revenue [Member]
Revenues [Abstract]
Revenue	77,897	78,184	145,664	150,468
SPINRAZA Royalties [Member]
Revenues [Abstract]
Revenue	61,012	59,627	111,258	113,444
Other Commercial Revenue [Member]
Revenues [Abstract]
Revenue	16,885	18,557	34,406	37,024
TEGSEDI and WAYLIVRA Revenue, Net [Member]
Revenues [Abstract]
Revenue	10,655	10,386	17,133	16,547
Licensing and Other Royalty Revenue [Member]
Revenues [Abstract]
Revenue	6,230	8,171	17,273	20,477
Research and Development Revenue [Member]
Revenues [Abstract]
Revenue	110,514	55,607	173,271	125,242
Collaborative Agreement Revenue [Member]
Revenues [Abstract]
Revenue	91,013	38,247	129,347	88,032
Eplontersen Joint Development Revenue [Member]
Revenues [Abstract]
Revenue	$ 19,501	$ 17,360	$ 43,924	$ 37,210