Name:	isis_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughTwoYearsPercentage
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The percentage of available-for-sale debt securities that mature beyond two years but within three years of the balance sheet date.

No definition available.

Name:	isis_AvailableForSaleSecuritiesDebtMaturitiesAfterTwoThroughThreeYearsPercentage
Namespace Prefix:	isis_
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:	isis_AvailableForSaleSecuritiesDebtMaturitiesTotalPercentage
Namespace Prefix:	isis_
Data Type:	num:percentItemType
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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:	isis_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearPercentage
Namespace Prefix:	isis_
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:	isis_AvailableForSaleSecuritiesDebtMaturitiesWithinTwoYearsPercentage
Namespace Prefix:	isis_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The ownership percentage represented by the entity's equity investments in companies with which it conducts business and which are not accounted for under the equity method of accounting.

No definition available.

Name:	isis_EquityInvestmentsOtherThanEquityMethodOwnershipPercentage
Namespace Prefix:	isis_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	isis_InvestmentsEquityInvestmentsOtherThanEquityMethodAbstract
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Data Type:	xbrli:stringItemType
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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:	isis_NumberOfPrivatelyHeldCompaniesInWhichEntityHasEquityInvestment
Namespace Prefix:	isis_
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 as available-for-sale securities.

No definition available.

Name:	isis_NumberOfPubliclyHeldCompaniesInWhichEntityHasEquityInvestment
Namespace Prefix:	isis_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAbstract
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Data Type:	xbrli:stringItemType
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Period Type:	duration

This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments (OTTI) of the subject investments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.7(c),9(a))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27405-111563

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Article 5

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (c)-(e)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563