Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2024	Jul. 26, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2024
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Document Transition Report	false
Entity File Number	000-19125
Entity Registrant Name	Ionis Pharmaceuticals, Inc.
Entity Central Index Key	0000874015
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-0336973
Entity Address, Address Line One	2855 Gazelle Court
Entity Address, City or Town	Carlsbad
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92010
City Area Code	760
Local Phone Number	931-9200
Title of 12(b) Security	Common Stock, $.001 Par Value
Trading Symbol	IONS
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		146,211,091