Collaborative Arrangements and Licensing Agreements, Research, Development and Commercialization Partners - GSK (Details) $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended
	Mar. 31, 2010 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) Drug	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue earned		$ 160,349	$ 110,927	$ 38,470	$ 36,874	$ 51,571	$ 49,121	$ 120,428	$ 62,583	$ 346,620	$ 283,703	$ 214,161
GSK [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of drugs currently in development | Drug										4
Cumulative payments received		155,000								$ 155,000
Number of drugs currently in clinical development with IONIS-TTR | Drug										3
Number of antisense drugs in development | Drug										2
Upfront payment received	$ 38,000
Maximum amount of payments receivable for license fee and substantive milestones		900,000								$ 900,000
Maximum amount of payments receivable for development milestones		157,500								157,500
Maximum amount of payments receivable for regulatory milestones		338,500								338,500
Maximum amount of payments receivable for commercialization milestones		255,000								255,000
Next prospective milestone		1,500								1,500
Next prospective license fee		45,000								45,000
Revenue earned										12,300	33,300	$ 37,300
Deferred revenue		2,100				$ 4,900				$ 2,100	$ 4,900
GSK [Member] | Revenue [Member] | Strategic Partner [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Concentration percentage										4.00%	12.00%	17.00%
GSK [Member] | IONIS-TTR [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments received		$ 70,000								$ 70,000