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Significant Accounting Policies, Cash, Cash Equivalents and Investments (Details) | Mar. 31, 2019 Company
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Cash, Cash Equivalents and Investments [Abstract] |
Number of publicly-held companies in which there is an equity ownership interest of less than 20% | 2
Number of privately-held companies in which there is an equity ownership interest of less than 20% | 4

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- Definition Number of privately-held companies, in which the entity has an equity ownership interest of less than 20%, with which it conducts business. These are accounted for under the cost method. + References No definition available. + Details
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- Definition Number of publicly-held companies, in which the entity has an equity ownership interest of less than 20%, with which it conducts business. These are accounted for at fair value. + References No definition available. + Details
Name: | ions_NumberOfPubliclyHeldCompaniesInWhichEntityHasEquityInvestment
Namespace Prefix: | ions_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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- References No definition available. + Details
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