Income Taxes - Reconciliation of Income Tax Provision (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes
Federal rate (as a percent)	21.00%
Reconciliation of the income tax provision computed at statutory tax rates to the income tax provision
Statutory federal income taxes	$ (4.7)	$ (8.0)	$ 32.0
State income taxes	0.2	(2.1)	11.9
Tax status change & other true-ups	0.8	0.9	1.3
Other true-ups	(2.4)	0.8	1.0
Equity compensation	(1.0)	(0.3)	(1.9)
Other permanent differences	(0.4)	(0.4)	(0.3)
Goodwill impairment			(11.2)
Research and development tax credits	2.2
Uncertain tax positions	(0.2)	3.7	(0.1)
Change in valuation allowance	(2.3)	3.9	32.4
Income tax (expense) benefit, net	$ (7.8)	$ (1.5)	$ 65.1

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Amount of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to expense for award under share-based payment arrangement. Excludes expense determined to be nondeductible upon grant or after for award under share-based payment arrangement.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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The Amount of income tax expense (benefit) attributable to an adjustment of a deferred tax liability or asset for of other true ups

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Amount of income tax expense (benefit) attributable to an adjustment of a deferred tax liability or asset for enacted changes in the Tax Status and other True-Ups

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