CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue:
Revenue	$ 163,813	$ 117,747	$ 461,026	$ 262,165
Expenses:
Cost of products sold	1,364	0	2,406	0
Research, development and patent	106,165	101,830	212,582	205,897
Selling, general and administrative	75,111	66,198	143,332	109,851
Total operating expenses	182,640	168,028	358,320	315,748
Income (loss) from operations	(18,827)	(50,281)	102,706	(53,583)
Other income (expense):
Investment income	13,735	5,137	25,880	8,748
Interest expense	(11,802)	(11,113)	(23,402)	(22,051)
Other income (expenses)	(45)	45	(192)	(123)
Income (loss) before income tax (expense) benefit	(16,939)	(56,212)	104,992	(67,009)
Income tax (expense) benefit	6,927	(358)	(24,119)	(372)
Net income (loss)	(10,012)	(56,570)	80,873	(67,381)
Net loss attributable to noncontrolling interest in Akcea Therapeutics, Inc.	9,136	16,215	2,694	25,606
Net income (loss) attributable to Ionis Pharmaceuticals, Inc. common stockholders	$ (876)	$ (40,355)	$ 83,567	$ (41,775)
Basic net income (loss) per share (in dollars per share)	$ (0.01)	$ (0.29)	$ 0.62	$ (0.30)
Shares used in computing basic net income (loss) per share (in shares)	140,247	128,712	139,419	127,030
Diluted net income (loss) per share (in dollars per share)	$ (0.01)	$ (0.29)	$ 0.61	$ (0.30)
Shares used in computing diluted net income (loss) per share (in shares)	140,247	128,712	142,499	127,030
Commercial Revenue [Member]
Revenue:
Revenue	$ 88,299	$ 57,198	$ 156,386	$ 99,221
SPINRAZA Royalties [Member]
Revenue:
Revenue	70,502	56,653	130,212	97,734
TEGSEDI Product Sales, Net [Member]
Revenue:
Revenue	9,865	0	16,619	0
Licensing and Other Royalty Revenue [Member]
Revenue:
Revenue	7,932	545	9,555	1,487
Research and Development Revenue Under Collaborative Agreements [Member]
Revenue:
Revenue	$ 75,514	$ 60,549	$ 304,640	$ 162,944