Name:	ions_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughTwoYearsPercentage
Namespace Prefix:	ions_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The percentage of available-for-sale debt securities that mature beyond two years but within three and one-half years of the balance sheet date.

No definition available.

Name:	ions_AvailableForSaleSecuritiesDebtMaturitiesAfterTwoThroughThreeAndOneHalfYearsPercentage
Namespace Prefix:	ions_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The aggregate percentage of all available-for-sale debt securities, regardless of maturity.

No definition available.

Name:	ions_AvailableForSaleSecuritiesDebtMaturitiesTotalPercentage
Namespace Prefix:	ions_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The percentage of available-for-sale debt securities that mature within one year of the balance sheet date.

No definition available.

Name:	ions_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearPercentage
Namespace Prefix:	ions_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The percentage of available-for-sale debt securities that mature within two years of the balance sheet date.

No definition available.

Name:	ions_AvailableForSaleSecuritiesDebtMaturitiesWithinTwoYearsPercentage
Namespace Prefix:	ions_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The maximum contract maturity period for the first range of available-for-sale securities, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	ions_MaximumContractMaturityPeriodRange1
Namespace Prefix:	ions_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The maximum contract maturity period for the second range of available-for-sale securities, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	ions_MaximumContractMaturityPeriodRange2
Namespace Prefix:	ions_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The maximum contract maturity period for the third range of available-for-sale securities, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	ions_MaximumContractMaturityPeriodRange3
Namespace Prefix:	ions_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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.

No definition available.

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

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.

No definition available.

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

- References

No definition available.

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

- References

No definition available.