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Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 485.8	$ 499.4
Unrecognized tax benefits	4.0	6.5	$ 8.2	$ 9.5
Unrecognized tax benefits that would impact effective tax rate	1.4	$ 1.4
Helguvik
Operating Loss Carryforwards [Line Items]
Discrete tax benefit (expense)	49.8
All U.S. and Portion of Icelandic Deferred Tax Assets
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 485.8

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
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Amount of unrecognized tax benefits.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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