For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the minimum concentration percentage qualifying as a concentration risk.

Name:	isis_ConcentrationRiskMinimumPercentage
Namespace Prefix:	isis
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of significant partners.

+ Details

Name:	isis_NumberOfSignificantPartners
Namespace Prefix:	isis
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" in the equation, this concept represents the concentration percentage derived from the division.

+ Details

Name:	isis_PercentageOfConcentrationRisk
Namespace Prefix:	isis
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ Details

Name:	us-gaap_ConcentrationRiskLineItems
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 21

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13537-108611

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13531-108611

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 18

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592

+ Details

Name:	us-gaap_ConcentrationRiskPercentage
Namespace Prefix:	us-gaap
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount to be collected within one year of the balance sheet date (or one operating cycle, if longer) from customers in accordance with the contractual provisions of long-term contracts or programs including amounts billed and unbilled as of the balance sheet date.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 3

-Subparagraph c

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.3(c))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_ReceivablesLongTermContractsOrPrograms
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Concentration of Business Risk (Details) (USD $)			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended				9 Months Ended	12 Months Ended
Concentration of Business Risk (Details) (USD $)	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2011 Partner A	Sep. 30, 2010 Partner A	Sep. 30, 2011 Partner A	Sep. 30, 2010 Partner A	Sep. 30, 2011 Partner B	Sep. 30, 2010 Partner B	Sep. 30, 2011 Partner B	Sep. 30, 2010 Partner B	Sep. 30, 2011 Partner C	Sep. 30, 2010 Partner C	Sep. 30, 2011 Partner C	Sep. 30, 2010 Partner C	Sep. 30, 2011 Regulus Therapeutics Inc. Contract receivables	Dec. 31, 2010 Regulus Therapeutics Inc. Contract receivables	Sep. 30, 2011 Contract receivables person	Dec. 31, 2010 Contract receivables person	Sep. 30, 2011 Contract receivables, Significant Partner One	Dec. 31, 2010 Contract receivables, Significant Partner One	Dec. 31, 2010 Contract receivables, Significant Partner Two
Concentration of business risk
Significant partner, defined (more than, as a percent)	10.00%
Significant partners, percent (as a percent)			80.00%	59.00%	75.00%	61.00%	10.00%	24.00%	16.00%	10.00%	3.00%	2.00%	3.00%	14.00%
Number of significant partners																	1	2
Percentage of contract receivable from significant partner (as a percent)															35.00%	44.00%			54.00%	30.00%	15.00%
Contract receivable (in dollars)	$ 1,858,000	$ 1,242,000													$ 646,000	$ 544,000