No definition available.

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

- Definition

Cumulative payments received since inception of the collaboration agreement included in the transaction price for the performance obligation.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Cumulative 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.

+ References

No definition available.

+ Details

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

- Definition

The maximum amount of payments receivable for commercialization milestones under the collaboration agreement.

+ References

No definition available.

+ Details

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

- Definition

The maximum amount of payments receivable for development milestones under the collaboration agreement.

+ References

No definition available.

+ Details

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

- Definition

Maximum amount of payments receivable for license fees and milestone payments under the collaboration agreement.

+ References

No definition available.

+ Details

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

- Definition

The maximum amount of payments receivable for sales milestones under the collaboration agreement.

+ References

No definition available.

+ Details

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

- Definition

The maximum amount of payments receivable per drug for substantive milestone payments under the collaboration agreement.

+ References

No definition available.

+ Details

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

- Definition

The maximum amount of payments receivable per drug or program for development milestone payments under the collaboration agreement.

+ References

No definition available.

+ Details

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

- Definition

The maximum amount of payments receivable per drug or program for license fees and/or substantive milestone payments under the collaboration agreement.

+ References

No definition available.

+ Details

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

- Definition

The maximum amount of payments receivable per drug or program for regulatory milestone payments under the collaboration agreement.

+ References

No definition available.

+ Details

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

- Definition

Milestone payments achieved under the collaboration agreement during the period and included in the transaction price for the performance obligation.

+ References

No definition available.

+ Details

Name:	ions_MilestonePaymentsAchievedAndIncludedInTransactionPriceForPerformanceObligation
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 countries where the drug is approved for treatment in patients.

+ References

No definition available.

+ Details

Name:	ions_NumberOfCountriesWhereDrugIsApprovedForUse
Namespace Prefix:	ions_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of medicines currently being developed under the collaboration agreement(s).

+ References

No definition available.

+ Details

Name:	ions_NumberOfMedicinesBeingDeveloped
Namespace Prefix:	ions_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of medicines currently being advanced under the collaboration agreement.

+ References

No definition available.

+ Details

Name:	ions_NumberOfMedicinesCurrentlyBeingAdvanced
Namespace Prefix:	ions_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of programs being advanced under the collaboration agreement.

+ References

No definition available.

+ Details

Name:	ions_NumberOfProgramsBeingAdvanced
Namespace Prefix:	ions_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of programs under which drugs are to be developed and commercialized under the collaboration agreement.

+ References

No definition available.

+ Details

Name:	ions_NumberOfProgramsUnderWhichDrugsAreToBeDevelopedAndCommercialized
Namespace Prefix:	ions_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage cash premium paid per share of the Company's common stock under the collaboration agreement.

+ References

No definition available.

+ Details

Name:	ions_PercentageCashPremiumPaidOnSharesPurchased
Namespace Prefix:	ions_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash premium paid on the purchase of the Company's common stock under the collaboration agreement.

+ References

No definition available.

+ Details

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

- Definition

The number of separate performance obligations under the collaboration agreement.

+ References

No definition available.

+ Details

Name:	ions_RevenueFromContractWithCustomerNumberOfSeparatePerformanceObligations
Namespace Prefix:	ions_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of consideration the Company earned or is eligible to earn under the collaboration agreement, including any variable consideration.

+ References

No definition available.

+ Details

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

- Definition

Royalty percentage received on the net sales of a drug by a collaboration partner under the collaboration agreement.

+ References

No definition available.

+ Details

Name:	ions_RoyaltyPercentageReceivedOnNetSalesOfDrug
Namespace Prefix:	ions_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Term of the collaboration agreement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	ions_TermOfCollaborationAgreement
Namespace Prefix:	ions_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Term of long-term open label extension study, in which patients participating in double blind placebo controlled trials of new medications are invited, on completion of the initial trial, to take the study drug for some further period, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	ions_TermOfExtensionStudy
Namespace Prefix:	ions_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of upfront payments received during the period under the collaboration agreement.

+ References

No definition available.

+ Details

Name:	ions_UpfrontPaymentReceived
Namespace Prefix:	ions_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The total amount of the upfront payment received, including the purchase of shares of the Company's stock, under the collaboration agreement.

+ References

No definition available.

+ Details

Name:	ions_UpfrontPaymentReceivedIncludingPurchaseOfStock
Namespace Prefix:	ions_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13531-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13537-108611

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

+ Details

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
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
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121556615&loc=SL49130531-203044

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130549-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121556615&loc=SL49130532-203044

+ Details

Name:	us-gaap_ContractWithCustomerLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow from the additional capital contribution to the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfCommonStock
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130543-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	srt_ProductOrServiceAxis=ions_SpinrazaRoyaltiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ions_LicensingAndOtherRoyaltiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ions_ResearchAndDevelopmentRevenueUnderCollaborativeAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=ions_CollaborativeArrangementsAndLicensingAgreementsBiogenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_RevenueFromContractWithCustomerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_CustomerConcentrationRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=ions_CollaborativeArrangementAndLicensingAgreementEnteredIntoInJanuary2012WithBiogenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=ions_CollaborativeArrangementAndLicensingAgreementEnteredIntoInDecember2017WithBiogenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=ions_CollaborativeArrangementAndLicensingAgreementEnteredIntoInApril2018WithBiogenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=ions_CollaborativeArrangementAndLicensingAgreementEnteredIntoInSeptember2013WithBiogenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ions_MedicinesForParkinsonsDiseaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ions_MedicinesForAmyotrophicLateralSclerosisMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ions_MedicinesForMultipleSystemAtrophyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ions_MedicinesForUndisclosedTargetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ions_AntisenseMoleculeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ions_IonisC9Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ions_TofersenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ions_Ion859Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ions_Ion464Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ions_Ion541Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=ions_CollaborativeArrangementAndLicensingAgreementEnteredIntoInDecember2012WithBiogenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ions_IonisMaptMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ions_Ion582Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Collaborative Arrangements and Licensing Agreements, Biogen (Details) $ in Thousands	1 Months Ended		3 Months Ended									12 Months Ended
	Sep. 30, 2013 USD ($) PerformanceObligation	Dec. 31, 2012 USD ($) Program	Sep. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($) PerformanceObligation	Dec. 31, 2020 USD ($) Medicine Program Country	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Apr. 30, 2018 USD ($) PerformanceObligation
Collaborative Arrangement and Licensing Agreement [Abstract]
Proceeds from issuance of common stock												$ 0	$ 0	$ 447,965
Revenue												729,264	1,122,599	599,674
SPINRAZA Royalties [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue												286,583	292,992	237,930
Licensing and Other Royalties [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue												8,117	17,205	14,755
R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue												$ 364,565	770,149	344,752
Biogen [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of medicines currently being developed \| Medicine												8
Revenue												$ 408,600	473,600	$ 375,000
Deferred revenue					$ 525,800							$ 465,800	$ 525,800
Biogen [Member] \| Revenue [Member] \| Strategic Partner [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Concentration percentage												56.00%	42.00%	63.00%
Biogen [Member] \| Minimum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments received												$ 2,800,000
Biogen [Member] \| SPINRAZA Royalties [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue												286,600	$ 293,000	$ 237,900
Biogen [Member] \| R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue												$ 122,000	180,600	$ 137,100
SPINRAZA [Member] \| Minimum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of countries where SPINRAZA is approved for use \| Country												50
Cumulative revenue earned												$ 1,300,000
Royalty percentage received on net sales of drug												11.00%
SPINRAZA [Member] \| Maximum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Royalty percentage received on net sales of drug												15.00%
SPINRAZA [Member] \| SPINRAZA Royalties [Member] \| Minimum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative revenue earned												$ 930,000
SPINRAZA [Member] \| R&D Revenue [Member] \| Minimum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative revenue earned												$ 435,000
New Antisense Medicines for the Treatment of SMA [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Royalty percentage received on net sales of drug												20.00%
Upfront payment received											$ 25,000
Maximum amount of payments receivable for license fees and milestones												$ 1,200,000
Maximum amount of payments receivable for development milestones												80,000
Maximum amount of payments receivable for commercialization milestones												180,000
Maximum amount of payments receivable for sales milestones												800,000
Next prospective payment												60,000
Number of separate performance obligations \| PerformanceObligation											1
Transaction price											$ 25,000
Revenue					8,300
2018 Strategic Neurology [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments received												$ 1,050,000
Royalty percentage received on net sales of drug												20.00%
Upfront payment received										$ 375,000
Next prospective payment												$ 7,500
Number of separate performance obligations \| PerformanceObligation															1
Transaction price															$ 552,000
Term of collaboration agreement												10 years
Upfront payment received, including purchase of stock										1,000,000
Proceeds from issuance of common stock										$ 625,000
Percentage cash premium paid on shares purchased										25.00%
Maximum amount of payments receivable per drug for substantive milestone payments												$ 270,000
Number of programs being advanced \| Program												8
Premium paid on shares purchased										$ 177,000
Cumulative payments included in transaction price for performance obligation												$ 608,000
Milestone payments achieved and included in transaction price for performance obligation												11,000	$ 30,000
2013 Strategic Neurology [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Upfront payment received	$ 100,000
Next prospective payment												$ 10,000
Number of separate performance obligations \| PerformanceObligation	1
Transaction price	$ 100,000
Number of medicines currently being advanced \| Medicine												6
Revenue			$ 18,000			$ (16,500)
2013 Strategic Neurology [Member] \| Minimum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments received												$ 270,000
2013 Strategic Neurology [Member] \| Licensing and Other Royalties [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue								$ 35,000
2013 Strategic Neurology [Member] \| R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments included in transaction price for performance obligation												$ 145,000
2013 Strategic Neurology [Member] \| Medicines for Parkinson's Disease [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of medicines currently being advanced \| Medicine												1
2013 Strategic Neurology [Member] \| Medicines for ALS [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of medicines currently being advanced \| Medicine												3
2013 Strategic Neurology [Member] \| Medicines for Multiple System Atrophy [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of medicines currently being advanced \| Medicine												1
2013 Strategic Neurology [Member] \| Medicines for Undisclosed Targets [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of medicines currently being advanced \| Medicine												1
2013 Strategic Neurology [Member] \| Antisense Molecule [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable per program for license fee and milestone payments												$ 260,000
Maximum amount of payments receivable per program for development milestones												60,000
Maximum amount of payments receivable per program for regulatory milestones												130,000
2013 Strategic Neurology [Member] \| IONIS-C9 [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue					10,000				$ 10,000
2013 Strategic Neurology [Member] \| Tofersen [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue								$ 5,000
2013 Strategic Neurology [Member] \| ION859 [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue						8,000
2013 Strategic Neurology [Member] \| ION464 [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue			18,000
2013 Strategic Neurology [Member] \| ION541 [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue			10,000
2012 Neurology [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments received												154,000
Upfront payment received		$ 30,000
Next prospective payment												25,000
Maximum amount of payments receivable per program for license fee and milestone payments												210,000
Maximum amount of payments receivable per program for development milestones												10,000
Maximum amount of payments receivable per program for regulatory milestones												130,000
Number of programs under which drugs are to be developed and commercialized \| Program		3
Revenue						$ 6,300
2012 Neurology [Member] \| R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments included in transaction price for performance obligation												40,000
2012 Neurology [Member] \| IONIS-MAPT [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments included in transaction price for performance obligation												57,000
Milestone payments achieved and included in transaction price for performance obligation			$ 12,000	$ 7,500	12,000		$ 7,500					$ 19,500
Term of extension study												1 year
Revenue					45,000
2012 Neurology [Member] \| ION582 [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue					$ 10,000