Name:	isis_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughTwoYearsPercentage
Namespace Prefix:	isis_
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 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
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:	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 percentage equity ownership of each of the entity's available-for-sale equity securities is less than this percentage.

No definition available.

Name:	isis_AvailableForSaleSecuritiesEquitySecuritiesOwnershipPercentageLessThan
Namespace Prefix:	isis_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The entity's cost method equity investments ownership percentage is less than this percentage.

No definition available.

Name:	isis_CostMethodInvestmentsOwnershipPercentageLessThan
Namespace Prefix:	isis_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	isis_InvestmentsEquityInvestmentsOtherThanEquityMethodAbstract
Namespace Prefix:	isis_
Data Type:	xbrli:stringItemType
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:	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.

No definition available.

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

- Details

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

This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the cost method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment.

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 18

-Paragraph 6

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 18

-Paragraph 6

-Subparagraph a

-Footnote 3a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_CostmethodInvestmentsOtherThanTemporaryImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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=6943989&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=6880815&loc=d3e20235-122688

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: 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=6872113&loc=d3e27357-111563

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 13, 22

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 5

-Section 03

-Paragraph 7

Reference 7: 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=6872113&loc=d3e27405-111563