No definition available.

Name:	isis_CollaborativeArrangementAndLicensingAgreementAbstract
Namespace Prefix:	isis_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Cumulative amount of payments received under the collaborative arrangement as of the end of the reporting period.

+ References

No definition available.

+ Details

Name:	isis_CumulativePaymentsReceived
Namespace Prefix:	isis_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the maximum amount of payments receivable per drug under the agreement.

+ References

No definition available.

+ Details

Name:	isis_MaximumAmountOfPaymentReceivablePerDrug
Namespace Prefix:	isis_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the maximum amount of payments receivable under the agreement.

+ References

No definition available.

+ Details

Name:	isis_MaximumAmountOfPaymentsReceivable
Namespace Prefix:	isis_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The number of development candidates that must be generated for the brain shuttle program by a mutually agreed deadline to prevent termination by either party under the collaborative arrangement.

+ References

No definition available.

+ Details

Name:	isis_NumberOfDevelopmentCandidatesThatMustBeGeneratedForBrainShuttleProgram
Namespace Prefix:	isis_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the next prospective milestone payment to be earned.

+ References

No definition available.

+ Details

Name:	isis_ProspectiveMilestonePayment
Namespace Prefix:	isis_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of deferred revenue as of balance sheet date. Deferred revenue represents collections of cash or other assets related to a revenue producing activity for which revenue has not yet been recognized. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 605

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 13.A.4(a).Q1 Response)

-URI http://asc.fasb.org/extlink&oid=27012821&loc=d3e214044-122780

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 13

-Section A

+ Details

Name:	us-gaap_DeferredRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of deferred revenue recognized for transactions arising during the current reporting period. Deferred revenue is a liability as of the balance sheet date related to a revenue producing activity for which revenue has not yet been recognized. Generally, an Entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 605

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 13.A.4(a).Q1)

-URI http://asc.fasb.org/extlink&oid=27012821&loc=d3e214044-122780

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 13

-Section A

+ Details

Name:	us-gaap_DeferredRevenueAdditions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of consideration recognized during the period for the milestone or milestones.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 605

-SubTopic 28

-Section 50

-Paragraph 2

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=19771982&loc=SL6892177-166501

+ Details

Name:	us-gaap_RevenueRecognitionMilestoneMethodRevenueRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

+ Details

Name:	us-gaap_Revenues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_CounterpartyNameAxis=isis_RocheMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=isis_CollaborativeArrangementsAndLicensingAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=isis_AgreementEnteredIntoInApril2013Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	isis_AchievementOfMilestoneAxis=isis_DevelopmentRegulatoryAndCommercialMilestonesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ProductOrServiceAxis=isis_HttMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	isis_AchievementOfMilestoneAxis=isis_LicenseAndSubstantiveMilestonesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	isis_AchievementOfMilestoneAxis=isis_DevelopmentMilestonesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	isis_AchievementOfMilestoneAxis=isis_RegulatoryMilestonesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	isis_AchievementOfMilestoneAxis=isis_CommercializationMilestonesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ProductOrServiceAxis=isis_BrainShuttleMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Collaborative Arrangements and Licensing Agreements, Traditional Pharmaceutical Alliances and Licensing - Roche (Details) $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended
	Jul. 31, 2015 USD ($)	Apr. 30, 2013 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) Candidate	Jun. 30, 2014 USD ($)
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue earned			$ 120,428	$ 57,076	$ 183,012	$ 85,237
Roche [Member] \| Collaborations and Licensing Agreements [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue earned			2,400	$ 2,400	4,800	$ 4,400
Deferred revenue			12,900		12,900
Roche [Member] \| Agreement Entered into in April 2013 [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Upfront fee recorded as deferred revenue		$ 30,000
Cumulative payments received			30,000		30,000
Next prospective milestone			10,000		10,000
Roche [Member] \| Agreement Entered into in April 2013 [Member] \| Subsequent Event [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Milestone payment earned	$ 22,000
Roche [Member] \| Agreement Entered into in April 2013 [Member] \| Development, Regulatory and Commercial Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payment receivable per drug			136,500		136,500
Roche [Member] \| Agreement Entered into in April 2013 [Member] \| HTT [Member] \| License Fee and Substantive Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable			362,000		362,000
Roche [Member] \| Agreement Entered into in April 2013 [Member] \| HTT [Member] \| Development Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable			67,000		67,000
Roche [Member] \| Agreement Entered into in April 2013 [Member] \| HTT [Member] \| Regulatory Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable			170,000		170,000
Roche [Member] \| Agreement Entered into in April 2013 [Member] \| HTT [Member] \| Commercialization Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable			80,000		$ 80,000
Roche [Member] \| Agreement Entered into in April 2013 [Member] \| Brain Shuttle [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of development candidates that must be generated for brain shuttle program \| Candidate					1
Roche [Member] \| Agreement Entered into in April 2013 [Member] \| Brain Shuttle [Member] \| Commercialization Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable			$ 50,000		$ 50,000