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Cumulative payments received since inception of the collaboration agreement included in the transaction price for the performance obligation.

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No definition available.

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Cumulative amount of payments received under the collaboration agreement as of the end of the reporting period.

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No definition available.

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Milestone payment achieved during the period.

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No definition available.

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

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No definition available.

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Number of medicines that need to be advanced in order to achieve the next potential payment under the collaboration agreement.

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No definition available.

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The number of medicines currently being developed under the collaboration agreement(s).

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Payments received under the collaboration agreement during the period included in the transaction price for the performance obligation.

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No definition available.

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- 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.

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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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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Collaborative Arrangements and Licensing Agreements, Biogen (Details) $ in Thousands		1 Months Ended	3 Months Ended				6 Months Ended
	Aug. 05, 2020 USD ($)	Jul. 31, 2020 USD ($)	Jun. 30, 2020 USD ($) Medicine	Mar. 31, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) Medicine	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue			$ 145,537			$ 163,813	$ 278,905	$ 461,026
SPINRAZA Royalties [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue			71,746			70,502	137,754	130,212
R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue			$ 55,803			75,514	$ 105,209	304,640
Biogen [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of medicines currently being developed \| Medicine			8				8
Cumulative payments received			$ 2,600,000				$ 2,600,000
Revenue			97,700			$ 102,400	185,200	$ 186,600
Deferred revenue			$ 486,600				$ 486,600		$ 525,800
Biogen [Member] \| Revenue [Member] \| Strategic Partner [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Concentration percentage			67.00%			63.00%	66.00%	41.00%
Biogen [Member] \| SPINRAZA Royalties [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue			$ 71,700			$ 70,500	$ 137,800	$ 130,200
Biogen [Member] \| R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue			26,000			$ 31,900	47,400	$ 56,400
2012 Neurology [Member] \| IONIS-MAPT [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Milestone payment achieved				$ 7,500
Payments included in transaction price for performance obligation				$ 7,500
Cumulative payments included in transaction price for performance obligation			$ 45,000				$ 45,000
2012 Neurology [Member] \| IONIS-MAPT [Member] \| Subsequent Event [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Milestone payment achieved	$ 12,000
2012 Neurology [Member] \| IONIS-MAPT [Member] \| Maximum [Member] \| Subsequent Event [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Next prospective payment	$ 25,000
2013 Strategic Neurology [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue					$ (16,500)
Number of medicines advanced to achieve next potential payment \| Medicine			1				1
2013 Strategic Neurology [Member] \| Maximum [Member] \| Subsequent Event [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Next prospective payment		$ 10,000
2013 Strategic Neurology [Member] \| ION464 [Member] \| Subsequent Event [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Milestone payment achieved		$ 18,000