Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Feb. 21, 2017	Jun. 30, 2016
Document and Entity Information [Abstract]
Entity Registrant Name	IONIS PHARMACEUTICALS INC
Entity Central Index Key	0000874015
Document Type	10-K
Document Period End Date	Dec. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 2,337,558,702
Entity Common Stock, Shares Outstanding		123,749,472
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY