CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue:
Revenue	$ 167,892	$ 145,395	$ 628,918	$ 407,559
Expenses:
Cost of products sold	967	0	3,373	0
Research, development and patent	104,366	95,255	316,948	301,153
Selling, general and administrative	60,036	68,712	203,368	178,563
Total operating expenses	165,369	163,967	523,689	479,716
Income (loss) from operations	2,523	(18,572)	105,229	(72,157)
Other income (expense):
Investment income	13,136	9,963	39,015	18,711
Interest expense	(12,002)	(11,282)	(35,404)	(33,332)
Other income (expenses)	(140)	(22)	(332)	(145)
Income (loss) before income tax (expense) benefit	3,517	(19,913)	108,508	(86,923)
Income tax (expense) benefit	14,915	(452)	(9,204)	(824)
Net income (loss)	18,432	(20,365)	99,304	(87,747)
Net loss attributable to noncontrolling interest in Akcea Therapeutics, Inc.	7,732	15,806	10,426	41,412
Net income (loss) attributable to Ionis Pharmaceuticals, Inc. common stockholders	$ 26,163	$ (4,559)	$ 109,730	$ (46,335)
Basic net income (loss) per share (in dollars per share)	$ 0.19	$ (0.03)	$ 0.81	$ (0.33)
Shares used in computing basic net income (loss) per share (in shares)	140,551	137,346	139,800	130,507
Diluted net income (loss) per share (in dollars per share)	$ 0.18	$ (0.03)	$ 0.79	$ (0.33)
Shares used in computing diluted net income (loss) per share (in shares)	143,408	137,346	142,821	130,507
Commercial Revenue [Member]
Revenue:
Revenue	$ 95,699	$ 82,756	$ 252,085	$ 181,975
SPINRAZA Royalties [Member]
Revenue:
Revenue	81,672	70,010	211,884	167,743
Product Sales, Net [Member]
Revenue:
Revenue	11,945	0	28,563	0
Licensing and Other Royalty Revenue [Member]
Revenue:
Revenue	2,082	12,746	11,638	14,232
Research and Development Revenue Under Collaborative Agreements [Member]
Revenue:
Revenue	$ 72,193	$ 62,639	$ 376,833	$ 225,584