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Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Deferred tax assets, valuation allowance	$ 49.8	$ 346.0
Realizable deferred tax assets	319.4
Deferred tax assets, net valuation release	296.3
Research and development tax credit carry forwards	109.6	71.9
Increase related to current year tax positions	3.9	$ 9.5	$ 11.7
Unrecognized tax benefits that would affect effective tax rate	53.9
Federal
Income Taxes [Line Items]
Operating loss carry forward, net	518.2
Research and development tax credit carry forwards	92.1
State and local jurisdiction
Income Taxes [Line Items]
Operating loss carry forward, net	340.8
Research and development tax credit carry forwards	$ 56.4

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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