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v3.21.1

Basis of Presentation (Details) - Akcea [Member] | Mar. 31, 2021 | Jul. 31, 2017
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Basis of Presentation [Abstract] |  |
Percentage ownership | 100.00% |
Maximum [Member] |  |
Basis of Presentation [Abstract] |  |
Percentage ownership |  | 100.00%

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- Definition The parent entity's interest in net assets of the subsidiary, expressed as a percentage. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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- References No definition available. + Details
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Namespace Prefix: | us-gaap_
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Balance Type: | na
Period Type: | duration

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- Details
Name: | srt_OwnershipAxis=ions_AkceaTherapeuticsIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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