Collaborative Arrangements and Licensing Agreements, Traditional Pharmaceutical Alliances and Licensing - AstraZeneca (Details) $ in Thousands	1 Months Ended					3 Months Ended		7 Months Ended	9 Months Ended
	Jul. 31, 2015 USD ($)	Nov. 30, 2014 USD ($)	Aug. 31, 2013 USD ($)	Jun. 30, 2013 USD ($)	Dec. 31, 2012 USD ($) Target Drug	Sep. 30, 2015 USD ($) AccountingUnit	Sep. 30, 2014 USD ($)	Jun. 30, 2013 USD ($) Drug	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue earned						$ 49,121	$ 44,063		$ 232,133	$ 129,300
AstraZeneca [Member] | Collaborations and Licensing Agreements [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue earned						1,500	$ 600		3,000	$ 19,700
Deferred revenue						66,700			66,700
AstraZeneca [Member] | Collaborations and Licensing Agreements [Member] | ISIS-STAT3-2.5 [Member] | Phase 2 Study [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Milestone payments to be earned						17,500			17,500
AstraZeneca [Member] | Agreement Entered into in December 2012 [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of targets | Target					5
Number of drugs the collaborative partner may license under a separate research program | Drug					3
Upfront fee received				$ 6,000	$ 25,000			$ 31,000
Revenue earned								$ 11,500
Cumulative payments received						63,500			63,500
Next prospective milestone						10,000			10,000
AstraZeneca [Member] | Agreement Entered into in December 2012 [Member] | Pre-specified Events [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable						858,000			858,000
AstraZeneca [Member] | Agreement Entered into in December 2012 [Member] | Development Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable						238,000			238,000
AstraZeneca [Member] | Agreement Entered into in December 2012 [Member] | Regulatory Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable						620,000			620,000
AstraZeneca [Member] | Agreement Entered into in December 2012 [Member] | Three Drugs [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of drugs the collaborative partner may license under a separate research program | Drug								3
Deferred revenue				$ 7,600				$ 7,600
AstraZeneca [Member] | Agreement Entered into in December 2012 [Member] | ISIS-STAT3-2.5 [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Upfront fee amortized into revenue						11,900			11,900
AstraZeneca [Member] | Amended Agreement Entered into in October 2014 [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Milestone payment received		$ 7,500
AstraZeneca [Member] | Agreement Entered into in August 2013 [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Upfront fee received			$ 800
Cumulative payments received						800			800
Next prospective milestone						3,300			3,300
AstraZeneca [Member] | Agreement Entered into in August 2013 [Member] | License Fee and Substantive Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable						163,200			163,200
AstraZeneca [Member] | Agreement Entered into in August 2013 [Member] | Research and Development Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable						45,300			45,300
AstraZeneca [Member] | Agreement Entered into in August 2013 [Member] | Regulatory Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable						105,000			105,000
AstraZeneca [Member] | Agreement Entered into in July 2015 [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Upfront fee received	$ 65,000
Next prospective milestone						$ 25,000			25,000
Number of units of accounting | AccountingUnit						1
AstraZeneca [Member] | Agreement Entered into in July 2015 [Member] | License Fee and Substantive Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Minimum amount of payments receivable						$ 4,000,000			4,000,000
AstraZeneca [Member] | Agreement Entered into in July 2015 [Member] | Development Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable						1,100,000			1,100,000
AstraZeneca [Member] | Agreement Entered into in July 2015 [Member] | Regulatory Milestones [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable						$ 2,900,000			$ 2,900,000