CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Revenue:
Revenue	$ 130,524	$ 141,919
Expenses:
Cost of sales	1,343	4,170
Research, development and patent	197,813	161,126
Selling, general and administrative	45,516	34,127
Total operating expenses	244,672	199,423
Loss from operations	(114,148)	(57,504)
Other income (expense):
Investment income	18,627	1,993
Interest expense	(1,608)	(2,122)
Interest expense related to sale of future royalties	(15,515)	0
Loss on investments	(529)	(6,625)
Other income	230	187
Loss before income tax expense	(112,943)	(64,071)
Income tax expense	(11,380)	(1,094)
Net loss	$ (124,323)	$ (65,165)
Basic net loss per share (in dollars per share)	$ (0.87)	$ (0.46)
Diluted net loss per share (in dollars per share)	$ (0.87)	$ (0.46)
Shares used in computing basic net loss per share (in shares)	142,735	141,599
Shares used in computing diluted net loss per share (in shares)	142,735	141,599
Commercial Revenue [Member]
Revenue:
Revenue	$ 67,768	$ 72,285
SPINRAZA Royalties [Member]
Revenue:
Revenue	50,247	53,818
TEGSEDI and WAYLIVRA Revenue, Net [Member]
Revenue:
Revenue	6,478	6,160
Licensing and Other Royalty Revenue [Member]
Revenue:
Revenue	11,043	12,307
Research and Development Revenue [Member]
Revenue:
Revenue	62,756	69,634
Collaborative Agreement Revenue [Member]
Revenue:
Revenue	38,334	49,784
Eplontersen Joint Development Revenue [Member]
Revenue:
Revenue	$ 24,422	$ 19,850