Cash purchase price for each equity award held, including stock options and restricted stock units (RSUs).

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Per share amount paid for the shares of the subsidiary purchased by the parent during the period, thereby effecting a change in total (consolidated) equity attributable to the parent.

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The aggregate amount paid by the entity to cancel subsidiary's outstanding equity awards.

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Represents the purchase by the parent of an additional equity interest in a subsidiary during the period, thereby effecting a change in total (consolidated) equity attributable to the parent. The purchase of the additional equity interest represented by this element increases the parent's controlling interest in the subsidiary.

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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.

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Amount expected to be recognized in earnings for the specified restructuring cost.

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Akcea Acquisition (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	3 Months Ended
	Oct. 31, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2017
Severance and Retention Related to Akcea Acquisition [Member]
Severance and Retention Costs [Abstract]
Beginning balance	$ 0.0	$ 0.0
Severance and retention expense		15.3
Amounts paid during the period		(0.6)
Severance and Retention Related to Akcea Acquisition [Member] \| Accrued Compensation [Member]
Severance and Retention Costs [Abstract]
Ending balance		14.7
Severance and Retention Related to Akcea Acquisition [Member] \| R&D Expenses [Member]
Severance and Retention Costs [Abstract]
Severance and retention expense		3.9
Severance and Retention Related to Akcea Acquisition [Member] \| SG&A Expenses [Member]
Severance and Retention Costs [Abstract]
Severance and retention expense		11.4
Severance Related to Akcea Acquisition [Member] \| Maximum [Member]
Severance and Retention Costs [Abstract]
Expected expenses		9.3
Retention Related to Akcea Acquisition [Member] \| Maximum [Member]
Severance and Retention Costs [Abstract]
Expected expenses		19.2
Akcea [Member]
Akcea Acquisition [Abstract]
Percentage ownership	100.00%		76.00%	100.00%
Shares purchased (in shares)	24.8
Purchase price per share (in dollars per share)	$ 18.15
Purchase price	$ 450.6
Direct transaction costs		$ 40.6
Cash purchase price of equity awards (in dollars per share)		$ 18.15
Payments for cancelled equity awards		$ 53.4
Unrecognized compensation cost related to non-vested RSUs	$ 59.3
Akcea [Member] \| Maximum [Member]
Akcea Acquisition [Abstract]
Percentage ownership	77.00%