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The maximum amount of payments receivable for commercialization milestones under the collaboration agreement.

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The maximum amount of payments receivable for regulatory milestones under the collaboration agreement.

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The next potential milestone payment to be earned under the collaboration agreement.

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The percentage of license fees, milestone payments and royalties paid as a sublicense fee to Ionis Pharmaceuticals, Inc. under the development, commercialization and license agreement and services agreement .

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The amount of the upfront payment received during the period under the collaboration agreement that was paid as a sublicense fee to Ionis Pharmaceuticals, Inc.

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The amount of the upfront payment received during the period under the collaboration agreement that was retained by the entity.

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The potential premium received if common stock is purchased in the future under a Stock Purchase Agreement (SPA) in conjunction with the collaboration agreement.

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The amount of consideration the Company is eligible to earn under the collaboration agreement, including any variable consideration.

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Royalty percentage received on the sales of a drug by a collaboration partner under the collaboration agreement.

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Strategic collaboration agreement.

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Sublicense fee payable.

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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.

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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

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Strategic Collaboration with Novartis (Details) $ in Thousands		1 Months Ended	3 Months Ended				9 Months Ended
	Feb. 22, 2019 USD ($) shares	Jul. 31, 2017 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Mar. 31, 2018	Mar. 31, 2017 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Jan. 31, 2017 PerformanceObligation
Strategic Collaboration with Novartis [Abstract]
Revenue			$ 20,624	$ 19,241			$ 211,064	$ 54,670
Revenue recognized from deferred revenue			2,300	6,800			18,000	36,500
Ionis [Member] \| Akcea [Member]
Strategic Collaboration with Novartis [Abstract]
Sublicense fee payable			75,000				75,000
Ionis [Member] \| Common Stock [Member] \| Akcea [Member]
Strategic Collaboration with Novartis [Abstract]
Issuance of stock (in shares) \| shares	2,837,373
Development Services for AKCEA-APO(a)-L [Member]
Strategic Collaboration with Novartis [Abstract]
Transaction price						$ 64,000
Development Services for AKCEA-APOCIII-L [Member]
Strategic Collaboration with Novartis [Abstract]
Transaction price						40,100
Delivery of AKCEA-APO(a)-L [Member]
Strategic Collaboration with Novartis [Abstract]
Transaction price						1,500
Delivery of AKCEA-APOCIII-L [Member]
Strategic Collaboration with Novartis [Abstract]
Transaction price						2,800
Licensing [Member]
Strategic Collaboration with Novartis [Abstract]
Revenue			136	12,000			6,172	12,000
Licensing [Member] \| Akcea [Member]
Strategic Collaboration with Novartis [Abstract]
Revenue	$ 150,000
AKCEA-APO(a)-L [Member]
Strategic Collaboration with Novartis [Abstract]
Maximum amount of payments receivable for milestones			675,000				675,000
Maximum amount of payments receivable for development milestones			25,000				25,000
Maximum amount of payments receivable for regulatory milestones			290,000				290,000
Maximum amount of payments receivable for commercialization milestones			360,000				$ 360,000
Royalty percentage received on sales of drug							20.00%
AKCEA-APOCIII-L [Member]
Strategic Collaboration with Novartis [Abstract]
Sublicense fee payable			75,000				$ 75,000
Maximum amount of payments receivable for milestones			530,000				530,000
Maximum amount of payments receivable for development milestones			25,000				25,000
Maximum amount of payments receivable for regulatory milestones			240,000				240,000
Maximum amount of payments receivable for commercialization milestones			265,000				$ 265,000
Royalty percentage received on sales of drug							20.00%
Research and Development and License Revenue Under Collaborative Agreement [Member]
Strategic Collaboration with Novartis [Abstract]
Revenue			8,544	7,241			$ 176,329	42,670
Novartis [Member]
Strategic Collaboration with Novartis [Abstract]
Upfront payment received						75,000
Portion of upfront payment retained						60,000
Portion of upfront payment paid as sublicense fee to Ionis						15,000
Number of separate performance obligations \| PerformanceObligation									4
Transaction price						108,400
Premium received on shares issued by lonis						28,400
Revenue			8,500	7,200			176,300	42,700
Next prospective milestone			25,000				$ 25,000
Percentage of license fees, milestone payments and royalties paid as sublicense fee to lonis							50.00%
Deferred revenue			10,800	$ 28,800			$ 10,800	$ 28,800
Potential premium received if Ionis common stock is purchased in the future						$ 5,000
Number of months from inception of agreement for IPO to be completed					15 months
Proceeds from sale of common stock to Novartis in a private placement		$ 50,000
Novartis [Member] \| AKCEA-APOCIII-L [Member]
Strategic Collaboration with Novartis [Abstract]
License fee receivable per drug			$ 150,000				150,000
Novartis [Member] \| Research and Development and License Revenue Under Collaborative Agreement [Member] \| Revenue [Member] \| Strategic Partner [Member]
Strategic Collaboration with Novartis [Abstract]
Concentration percentage			100.00%
Novartis [Member] \| Delivery of AKCEA-APO(a)-L [Member]
Strategic Collaboration with Novartis [Abstract]
Revenue							$ 5,500