No definition available.

Name:	ions_CollaborativeArrangementAndLicensingAgreementAbstract
Namespace Prefix:	ions_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Cumulative amount of payments received under the collaboration agreement as of the end of the reporting period.

+ References

No definition available.

+ Details

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Namespace Prefix:	ions_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Milestone payment achieved during the period.

+ References

No definition available.

+ Details

Name:	ions_MilestonePaymentAchieved
Namespace Prefix:	ions_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The next potential payment to be earned under the collaboration agreement.

+ References

No definition available.

+ Details

Name:	ions_NextPotentialPayment
Namespace Prefix:	ions_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The number of collaboration agreements with the collaboration partner.

+ References

No definition available.

+ Details

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Namespace Prefix:	ions_
Data Type:	xbrli:integerItemType
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- Definition

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.

+ References

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+ Details

Name:	us-gaap_ConcentrationRiskPercentage1
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Balance Type:	credit
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- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Collaborative Arrangements and Licensing Agreements, AstraZeneca (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) Agreement	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	$ 133,367	$ 297,214
R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	$ 49,406	$ 229,126
AstraZeneca [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of collaboration agreements \| Agreement	2
Cumulative payments received	$ 300,000
Deferred revenue	$ 21,300		$ 25,000
AstraZeneca [Member] \| Revenue [Member] \| Strategic Partner [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Concentration percentage	10.00%	1.00%
AstraZeneca [Member] \| R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	$ 13,800	$ 4,000
Cardiovascular, Renal and Metabolic Diseases [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of collaboration agreements \| Agreement	1
Milestone payment achieved	$ 10,000
Next prospective payment	30,000
Revenue	10,000
Cardiovascular, Renal and Metabolic Diseases [Member] \| R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	$ 10,000
Oncology [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of collaboration agreements \| Agreement	1