CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenue:
Revenue	$ 159,767	$ 133,093	$ 435,478	$ 370,450
Expenses:
Cost of sales	1,515	3,079	10,430	8,616
Research, development and patent	182,990	184,770	524,875	463,878
Selling, general and administrative	34,416	31,093	102,345	148,747
Total operating expenses	218,921	218,942	637,650	621,241
Loss from operations	(59,154)	(85,849)	(202,172)	(250,791)
Other income (expense):
Investment income, net	7,524	872	13,447	8,236
Interest expense	(2,139)	(2,340)	(6,391)	(7,111)
Gain (loss) on investments	2,347	4,013	(10,616)	4,885
Other income (expense)	4,713	(469)	(7,923)	(9,283)
Loss before income tax (expense) benefit	(46,709)	(83,773)	(213,655)	(254,064)
Income tax (expense) benefit	(283)	1,307	(3,637)	854
Net loss	$ (46,992)	$ (82,466)	$ (217,292)	$ (253,210)
Basic net loss per share (in dollars per share)	$ (0.33)	$ (0.58)	$ (1.53)	$ (1.8)
Diluted net loss per share (in dollars per share)	$ (0.33)	$ (0.58)	$ (1.53)	$ (1.8)
Shares used in computing basic net loss per share (in shares)	141,950	141,139	141,782	140,958
Shares used in computing diluted net loss per share (in shares)	141,950	141,139	141,782	140,958
Commercial Revenue [Member]
Revenue:
Revenue	$ 72,410	$ 84,820	$ 222,879	$ 255,129
SPINRAZA Royalties [Member]
Revenue:
Revenue	61,647	66,572	175,092	198,726
TEGSEDI and WAYLIVRA Revenue, Net [Member]
Revenue:
Revenue	5,920	15,519	22,467	46,901
Licensing and Other Royalty Revenue [Member]
Revenue:
Revenue	4,843	2,729	25,320	9,502
Research and Development Revenue [Member]
Revenue:
Revenue	87,357	48,273	212,599	115,321
Collaborative Agreement Revenue [Member]
Revenue:
Revenue	69,250	48,273	157,282	115,321
Eplontersen Joint Development Revenue [Member]
Revenue:
Revenue	$ 18,107	$ 0	$ 55,317	$ 0