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Represents the minimum amount of payments receivable under the agreement.

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Represents the number of drugs currently in clinical development under the collaboration agreement.

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Represents the amount of upfront payments received during the period under the agreement.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Collaborative Arrangements and Licensing Agreements, Research, Development and Commercialization Partners - GSK (Details) $ in Thousands	1 Months Ended	3 Months Ended
	Mar. 31, 2010 USD ($)	Mar. 31, 2016 USD ($) Drug	Mar. 31, 2015 USD ($)
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue earned		$ 36,874	$ 62,583
GSK [Member] \| Collaborations and Licensing Agreements [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of drugs currently in development \| Drug		5
Upfront fee received	$ 38,000
Cumulative payments received		$ 145,000
Next prospective milestone		1,500
Revenue earned		5,000	$ 16,500
Deferred revenue		$ 4,400
GSK [Member] \| Collaborations and Licensing Agreements [Member] \| Revenue [Member] \| Strategic Partner [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Concentration percentage		14.00%	26.00%
GSK [Member] \| Collaborations and Licensing Agreements [Member] \| Pre-specified Events [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Minimum amount of payments receivable		$ 1,000,000
GSK [Member] \| Collaborations and Licensing Agreements [Member] \| Development Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable		168,500
GSK [Member] \| Collaborations and Licensing Agreements [Member] \| Regulatory Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable		363,500
GSK [Member] \| Collaborations and Licensing Agreements [Member] \| Commercialization Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable		338,000
GSK [Member] \| Collaborations and Licensing Agreements [Member] \| IONIS-TTR [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments received		$ 60,000
GSK [Member] \| Collaborations and Licensing Agreements [Member] \| IONIS-HBV, IONIS-HBV-L, IONIS-GSK4-L, and IONIS-RHO-2.5 [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of drugs currently in development \| Drug		4
GSK [Member] \| Collaborations and Licensing Agreements [Member] \| IONIS-HBV and IONIS-HBV-L [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of drugs currently in development \| Drug		2
GSK [Member] \| Collaborations and Licensing Agreements [Member] \| IONIS-HBV-L [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Milestone payment earned		$ 1,500