CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) [Abstract]
Net income (loss)	$ (28,597)	$ (479,743)	$ 287,259
Unrealized gains (losses) on investments, net of tax	(11,486)	3,729	6,633
Currency translation adjustment	(111)	617	93
Adjustments to other comprehensive loss from purchase of noncontrolling interest of Akcea Therapeutics, Inc.	0	(127)	0
Comprehensive income (loss)	(40,194)	(475,524)	293,985
Comprehensive income (loss) attributable to noncontrolling interest in Akcea Therapeutics, Inc.	0	(35,480)	9,116
Comprehensive income (loss) attributable to Ionis Pharmaceuticals, Inc. common stockholders	$ (40,194)	$ (440,044)	$ 284,869