Collaborative Arrangements and Licensing Agreements, AstraZeneca (Details) $ in Thousands	1 Months Ended			3 Months Ended		12 Months Ended
	Dec. 31, 2021 USD ($) Component Agreement PerformanceObligation Medicine	Jul. 31, 2015 USD ($) PerformanceObligation	Dec. 31, 2012 USD ($)	Dec. 31, 2021 USD ($) Component Agreement PerformanceObligation Medicine	Jun. 30, 2020 USD ($)	Dec. 31, 2021 USD ($) Component Agreement PerformanceObligation Medicine	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue						$ 810,456	$ 729,264	$ 1,122,599
R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue						468,061	364,565	$ 770,149
AstraZeneca [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Deferred revenue	$ 0			$ 0		$ 0	$ 10,000
AstraZeneca [Member] | Revenue [Member] | Strategic Partner [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Concentration percentage						31.00%	12.00%	3.00%
AstraZeneca [Member] | R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue						$ 254,600	$ 88,000	$ 28,100
Eplontersen Collaboration [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Upfront payment received	200,000
Maximum amount of payments receivable for development and regulatory milestones	485,000			485,000		485,000
Maximum amount of payments receivable for sales-related milestones	$ 2,900,000			$ 2,900,000		$ 2,900,000
Royalty percentage received on sales of medicine in U.S.						20.00%
Number of material components | Component	4			4		4
Percentage of costs associated with ongoing global Phase 3 development program paid by AstraZeneca						55.00%
Number of separate performance obligations | PerformanceObligation	1			1		1
Transaction price	$ 200,000			$ 200,000		$ 200,000
Next prospective payment	50,000			50,000		50,000
Revenue	200,000
Research and Development Collaborations [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments received	$ 386,000			$ 386,000		$ 386,000
Number of collaboration agreements | Agreement	2			2		2
Number of medicines currently being developed | Medicine	6			6		6
Cardiovascular, Renal and Metabolic Diseases Collaboration [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of licensed medicines | Medicine	5			5		5
Upfront payment received		$ 65,000
Number of collaboration agreements | Agreement	1			1		1
Minimum amount of payments receivable for license fees and milestones	$ 5,500,000			$ 5,500,000		$ 5,500,000
Maximum amount of payments receivable for development milestones	1,100,000			1,100,000		1,100,000
Maximum amount of payments receivable for regulatory milestones	2,900,000			2,900,000		2,900,000
Maximum amount of payments receivable for commercialization milestones	1,500,000			1,500,000		1,500,000
Number of separate performance obligations | PerformanceObligation		1
Transaction price		$ 65,000
Next prospective payment	10,000			10,000		10,000
Revenue				10,000		10,000
Cardiovascular, Renal and Metabolic Diseases Collaboration [Member] | Minimum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments received	282,000			282,000		282,000
Cardiovascular, Renal and Metabolic Diseases Collaboration [Member] | Target for Metabolic Disease [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue						30,000
Cardiovascular, Renal and Metabolic Diseases Collaboration [Member] | R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments included in transaction price for performance obligation	$ 90,000			$ 90,000		$ 90,000
Oncology Collaboration [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Upfront payment received			$ 31,000
Number of collaboration agreements | Agreement	1			1		1
Maximum amount of payments receivable for license fees and milestones	$ 160,000			$ 160,000		$ 160,000
Maximum amount of payments receivable for development milestones	42,000			42,000		42,000
Maximum amount of payments receivable for regulatory milestones	105,000			105,000		105,000
Next prospective payment	12,000			12,000		12,000
Oncology Collaboration [Member] | Minimum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments received	$ 141,000			$ 141,000		$ 141,000
Oncology Collaboration [Member] | ION736 [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue					$ 13,000		$ 13,000