The number of options to extend the lease under the lessee's lease.

No definition available.

Name:	ions_LesseeNumberOfOptionsToExtendLease
Namespace Prefix:	ions_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of options to extend the lease under the lessee's operating lease.

+ References

No definition available.

+ Details

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

- Definition

Term of lessee's lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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

- Definition

Term of lessee's lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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

- Definition

Number of lots of undeveloped land adjacent to the Company's headquarters in Carlsbad, California included in purchase and sale agreement.

+ References

No definition available.

+ Details

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

- Definition

Number of purchase and sale agreements entered into with a real estate investor.

+ References

No definition available.

+ Details

Name:	ions_NumberOfPurchaseAndSaleAgreementsEnteredIntoWithRealEstateInvestor
Namespace Prefix:	ions_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Indicates line item in statement of income or comprehensive income that includes impairment of long-lived asset held for use.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 360
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482099/360-10-50-2

+ Details

Name:	us-gaap_ImpairmentLongLivedAssetHeldForUseStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration
Namespace Prefix:	us-gaap_
Data Type:	enum2:enumerationSetItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 360
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482099/360-10-50-2

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482130/360-10-45-4

+ Details

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

- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147478964/842-20-50-3

+ Details

Name:	us-gaap_LesseeOperatingLeaseRenewalTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 12
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-12

+ Details

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

- References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=ions_HeadquartersLocationInCarlsbadCaliforniaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_LandMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=ions_DevelopmentChemistryAndManufacturingFacilityInOceansideCaliforniaMember
Namespace Prefix:
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Real Estate Transactions (Details) $ in Millions	1 Months Ended		9 Months Ended
Real Estate Transactions (Details) $ in Millions	Aug. 31, 2023 USD ($) Lot	Oct. 31, 2022 USD ($) Agreement	Sep. 30, 2023 Option
Headquarters Location in Carlsbad, California [Member]
Real Estate Transactions [Abstract]
Number of purchase and sale agreements entered into with real estate investor \| Agreement		2
Proceeds from sale of real estate assets		$ 263.4
Initial term of lease			15 years
Number of options to extend lease \| Option			2
Term of lease extension			5 years
Undeveloped Land in Carlsbad, California [Member]
Real Estate Transactions [Abstract]
Number of lots of undeveloped land included in purchase and sale agreement \| Lot	2
Proceeds from sale of real estate assets	$ 33.0
Initial term of lease			15 years
Number of options to extend lease \| Option			2
Term of lease extension			5 years
Development Chemistry and Manufacturing Facility in Oceanside, California [Member]
Real Estate Transactions [Abstract]
Impairment charge	$ 18.0
Impairment, Long-Lived Asset, Held-for-Use, Statement of Income [Extensible Enumeration]	Selling, general and administrative