Collaborative Arrangements and Licensing Agreements, Roche (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2022 USD ($)	Dec. 31, 2022 USD ($) Indication	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Oct. 31, 2018 USD ($) PerformanceObligation	Apr. 30, 2013 USD ($) PerformanceObligation
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue		$ 587,367	$ 810,456	$ 729,264
R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue		284,009	468,061	$ 364,565
Roche [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Deferred revenue		$ 22,400	$ 31,600
Roche [Member] | Revenue [Member] | Strategic Partner [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Concentration percentage		11.00%	2.00%	1.00%
Roche [Member] | R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue		$ 67,200	$ 17,200	$ 5,900
Collaboration to Develop Treatments for Huntington's Disease with Roche [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable over term of collaboration		395,000
Maximum amount of upfront payments over term of collaboration		30,000
Maximum amount of license fees over term of collaboration		45,000
Maximum amount of development milestone payments over term of collaboration		70,000
Maximum amount of regulatory milestone payments over term of collaboration		170,000
Maximum amount of sales milestone payments over term of collaboration		80,000
Maximum amount of milestone payments for each additional medicine successfully developed over term of collaboration		136,500
Cumulative payments received		150,000
Next payment to be achieved		17,500
Number of separate performance obligations | PerformanceObligation							1
Transaction price							$ 30,000
Revenue					$ 35,000
IONIS-FB-L for Complement-Mediated Diseases [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable over term of collaboration		810,000
Maximum amount of upfront payments over term of collaboration		75,000
Maximum amount of license fees over term of collaboration		35,000
Maximum amount of development milestone payments over term of collaboration		145,000
Maximum amount of regulatory milestone payments over term of collaboration		279,000
Maximum amount of sales milestone payments over term of collaboration		280,000
Cumulative payments received		130,000
Next payment to be achieved		$ 90,000
Number of separate performance obligations | PerformanceObligation						1
Transaction price						$ 75,000
Number of disease indications | Indication		2
Royalty percentage received on net sales of medicine		20.00%
Revenue	$ 35,000
IONIS-FB-L for Complement-Mediated Diseases [Member] | GA [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of disease indications | Indication		1
IONIS-FB-L for Complement-Mediated Diseases [Member] | IgAN [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of disease indications | Indication		1