CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Revenue:
Revenue	$ 119,497	$ 130,524
Expenses:
Cost of sales	2,151	1,343
Research, development and patent	214,215	197,813
Selling, general and administrative	52,644	45,516
Total operating expenses	269,010	244,672
Loss from operations	(149,513)	(114,148)
Other income (expense):
Investment income	26,285	18,627
Interest expense	(4,151)	(1,608)
Interest expense related to sale of future royalties	(17,959)	(15,515)
Gain (loss) on investments	2,333	(529)
Other income	277	230
Loss before income tax expense	(142,728)	(112,943)
Income tax expense	(75)	(11,380)
Net loss	$ (142,803)	$ (124,323)
Basic net loss per share (in dollars per share)	$ (0.98)	$ (0.87)
Diluted net loss per share (in dollars per share)	$ (0.98)	$ (0.87)
Shares used in computing basic net loss per share (in shares)	145,538	142,735
Shares used in computing diluted net loss per share (in shares)	145,538	142,735
Commercial Revenue [Member]
Revenue:
Revenue	$ 59,593	$ 67,768
SPINRAZA Royalties [Member]
Revenue:
Revenue	38,455	50,247
WAINUA Royalties [Member]
Revenue:
Revenue	1,125	0
Other Commercial Revenue [Member]
Revenue:
Revenue	20,013	17,521
Research and Development Revenue [Member]
Revenue:
Revenue	59,904	62,756
Collaborative Agreement Revenue [Member]
Revenue:
Revenue	49,345	38,334
WAINUA Joint Development Revenue [Member]
Revenue:
Revenue	$ 10,559	$ 24,422