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

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No definition available.

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Number of milestone payments recognized in full during the period.

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No definition available.

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Number of targets advanced under the collaboration agreement.

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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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- Definition

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	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($) Payment Target	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	$ 159,767	$ 133,093	$ 435,478	$ 370,450
SPINRAZA Royalties [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	61,647	66,572	175,092	198,726
R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	87,357	48,273	212,599	115,321
Biogen Collaborations [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments received	3,400,000		3,400,000
Revenue	89,000	$ 84,000	259,700	$ 262,100
Deferred revenue	$ 360,200		$ 360,200		$ 407,500
Biogen Collaborations [Member] \| Revenue [Member] \| Strategic Partner [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Concentration percentage	56.00%	63.00%	60.00%	71.00%
Biogen Collaborations [Member] \| SPINRAZA Royalties [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	$ 61,600	$ 66,600	$ 175,100	$ 198,700
Biogen Collaborations [Member] \| R&D Revenue [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	27,400	$ 17,400	84,600	$ 63,400
Neurology Collaborations with Biogen [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	$ 13,000
Number of targets advanced \| Target	2
Number of milestone payments recognized in full \| Payment	1
2013 Strategic Neurology Collaboration with Biogen [Member] \| Maximum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Next prospective payment	$ 10,000		$ 10,000