CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue:
Revenue	$ 587,367	$ 810,456	$ 729,264
Expenses:
Cost of sales	14,116	10,842	11,947
Research, development and patent	833,147	643,453	535,077
Selling, general and administrative	150,295	186,347	354,322
Total operating expenses	997,558	840,642	901,346
Loss from operations	(410,191)	(30,186)	(172,082)
Other income (expense):
Investment income	25,331	10,044	30,562
Interest expense	(8,122)	(9,349)	(9,510)
Gain (loss) on investments	(7,333)	10,103	16,540
Gain on sale of real estate assets	149,604	0	0
Other expenses	(7,274)	(9,760)	(62)
Loss before income tax benefit (expense)	(257,985)	(29,148)	(134,552)
Income tax benefit (expense)	(11,737)	551	(345,191)
Net loss	(269,722)	(28,597)	(479,743)
Net loss attributable to noncontrolling interest in Akcea Therapeutics, Inc.	0	0	35,480
Net loss attributable to Ionis Pharmaceuticals, Inc. common stockholders	$ (269,722)	$ (28,597)	$ (444,263)
Basic net loss per share (in dollars per share)	$ (1.9)	$ (0.2)	$ (3.18)
Shares used in computing basic net loss per share (in shares)	141,848	141,021	139,612
Diluted net loss per share (in dollars per share)	$ (1.9)	$ (0.2)	$ (3.18)
Shares used in computing diluted net loss per share (in shares)	141,848	141,021	139,612
Commercial Revenue [Member]
Revenue:
Revenue	$ 303,358	$ 342,395	$ 364,699
SPINRAZA Royalties [Member]
Revenue:
Revenue	242,314	267,776	286,583
TEGSEDI and WAYLIVRA Revenue, Net [Member]
Revenue:
Revenue	30,051	55,500	69,999
Licensing and Other Royalty Revenue [Member]
Revenue:
Revenue	30,993	19,119	8,117
Research and Development Revenue [Member]
Revenue:
Revenue	284,009	468,061	364,565
Collaborative Agreement Revenue [Member]
Revenue:
Revenue	207,222	468,061	364,565
Eplontersen Joint Development Revenue [Member]
Revenue:
Revenue	$ 76,787	$ 0	$ 0